1995 - 2002 GM OBS Truck 4WAL ABS Module DTC C0268 Repair Kelsey-Hayes EBC310 Teardown (Chevy & GMC)

[@tklykun9858]

I am VERY grateful to you for posting this excellent video. Im a retired marine mechanic and have a 98 K 3500 Dually 7.4 gas with the hydraulic booster. Sometimes the brakes just feel a bit different enough to make me think I better check things out sooner than later. This has saved me time and aggravation not knowing about the differences and the availability issues. Thank you

[@dickeyspaz3222]

Dr. Shock you are the man with all of these OBS tutorials !

[@williammorgan5125]

Man you are indeed a blessing. I have a 93 that has the same issue. Praying mine only has a ground issue as the suburban was a Chicago burban..Thanks a million for the master class diagnosis!!!

[@crawford323]

Yes yes yes! This is so needed.

[@crazeyspivey]

That was one of the most thorough and superbly well-done presentation that I have ever watched.......Bravo, Bravo, Bravo! I dont know how in the world you have remembered all the various ABS types, models, and part numbers and the minute details that you discussed. Amazing indeed! I was waiting to see if you were as bad as me, and were going to prep and repaint the rusty base plate that lies under the ABS unit........or wipe it down with some used tranny fluid to inhibit the rust. I also use anti-seize on all the brake line fittings (after wire brushing the threads), so they do not break-off on the next guy. I like the plug caps you used to reduce loss of brake fluid. I ordered a couple different sizes of rubber vacuum plugs from McMaster Carr, and they work perfect as caps over the brake line flare ends, with zero leaks......."no runs, no drips, no errors", to quote Johnny Bench. The rubber plugs also fit into the bleeder screw holes which stops leakage to allow a thorough cleaning of the bleeder screws before putting back on. I thought that the problem would surely be down on the wire-stranded ground cable that goes from the frame over to the rear of the engine, and up to the front (I believe behind the alternator, as these straps turn green and white with corrosion pretty frequently. I have 2 1999 Suburbans, and both had this issue.....wish they had used rubber incased ground straps similar to battery cables for these grounding locations. Again, superb presentation..........all the way to the end where you hooked the engine hood light back up. Very thorough.

[@kiddbrother3]

I got a used abs unit & check all numbers & letters they all matched! thank you for all information great job!

[@elky82]

lots of very useful information in this video, thank you for your expertise

[@Dark_Knight_USA]

Greetings: Good thing I like the older trucks. No 4 wheel ABS. Thx 4 the share.

[@FinnWest69]

Fantastic video, just what I needed so bad! Thank you!

[@benkanobe7500]

I just used your link and purchased the Tech II out of Canada. I hope I can figure out how to use it. I will want to perform the automated bleed (Gas) once I get everthing back together. I will look at your older KZbin where you went through the automated bleed with your Tech II. Hopefully, there will be enough info for me to connect mine and use it correctly.

[@billdennis2993]

Thx DS for an informative and excellent video production

[@dennisgentile888]

Thank you for all the great information

[@MrZayne8]

First off great video. I am trying to understand the ABS setup in the 1995 G20 van I picked up recently and this video goes into some of the specifics in the differences between similar year range GM vehicles. It stops decently but I have a slight leak from the driver side caliper where the brake hose bolts on. The wheel cylinders are noth beginning to seep a little fluid so I decided to go ahead and rebuild the whole brake system. I bought new rotors, calipers, rubber hoses, pads, rear shoes & hardware, wheel cylinders, etc but now I am stumped as to whether or not I will need to bleed the ABS BPMV before or after or bleed it at all. I have been pulling various parts off of both a '95 G20 and a '94 G20 at a wreckijg yard, both of which are ABS. I aimed to get the BPMV with EBCM from the '95 (to have a spare) on my next trip but since I had them cut a fender off I believe they crushed what was left after destroying the front end. It has/had the 5.7L/4L60e with vacuum brakes which is what I have. The '94 G20 should still have the BPMV and EBCM under it but that van has hydroboost brakes so at least the EBCM wont be compatible with mine. Your video has at least helped me begin to he able to make that distinction. My EBCM and BPMV seem to be working as there is no ABS light, but I am not sure as I have not encountered hard braking or slippery conditions. Do you need an OBD1 Tech1 GM scanner to be able to test your Kelsey Hayes ABS? Since these parts are discontinued and challenging to find will these vehicles necessarily need to be retired from daily service or can the ABS be deleted in favor of a simpler pre-ABS factory type configuration?

[@DrShock]

Personally I would not remove or alter the 4WAL ABS system for the insurance and legal liability reasons that _will_ arise in the event of an accident. Many of these trucks are three decades old at this point, with none of the 4WAL ABS parts produced in the aftermarket. As a result they will increasingly need to be retired from daily driver service imo. I try to capture as much detail as is available for these vintage trucks and vans when doing repairs, in the hopes to give them a few more years of road life though. You can use a Tech2 with the pre-ODBII vehicle interface plug, as a better option to the Tech1.

[@B2sdad512]

Great video, very helpful. Thank you.

[@markii72]

I have a '99 old body style K1500 Suburban, and had trouble with an intermittent ABS light. It showed C0221 RF Wheel Speed Sensor Circuit Open, C0222 RF Wheel Speed Signal Missing, C0223 RF Wheel Speed Signal Erratic error codes in the memory. I checked the wheel speed sensor, wiring and connectors, power supply to the EBCM, the output signal of the sensor (oscilloscope), resistance of the sensor (DVOM), all perfectly to specification according to the GM service manual. I figured there is nothing left in that system so I got a used EBCM. The used EBCM (from a K1500 Yukon) has been working reliable for weeks, when starting the engine the ABS light comes on and goes off after 2-3 seconds like it should. But the used module seems questionable too: Neither a Tech2 or a VCX Nano can talk to it, whereas I was able to read out the original EBCM just fine. Do you have an idea what could be the reason for that?

[@DrShock]

Hmm, I'd say if a Tech2 could communicate with the original EBCM then you have a good working communications bus wiring in your truck. But if the replacement EBCM has no communications with the Tech2, then I would suspect that EBCM as the problem not the truck. Easy test is just swap the modules again and confirm communications resume. Check the condition of the pins in the EBCM connector of course, as well.

[@DALLASBOYJT12]

Just watched Your Video! It was so informative and very detailed! I'm not a mechanic but I'm in a Situation where I think my ABS pump is going bad and I have to find a Replacement at A Junkyard Also. I've changed out Hoses, calipers, master cylinder and Brake Booster! But my left front wheel keeps locking up after driving awhile, I'm guessing this is what I have to do next..thanks

[@haccoon5458]

I have a ‘95 Cheyenne 1500 and I found that it has a JB5 and a D on the combination valve. My problem is, I don’t have any dash lights on, but my driver side wheel is overheating and it caught fire once. The brakes were locking up. I was told it might be the hose. So I replaced the hose and the caliper. It worked fine for 2 years. But now it’s doing it again. It pulls to the right when braking. Even started shaking bad when I drove it. I can only assume it’s the ABS module. It’s kinda weird that it ran fine for a couple of years. Perhaps one of the solenoids is sticking? And that’s why it went fine for two years? I guess I kinda cleaned it out. That’s my best guess. I would really hate to get rid of it. My biggest question is you said in the video the combination valves aren’t interchangeable. So I have to find one with a D correct? Unfortunately I bought one off amazon but it has an A on the combo valve😢

[@DrShock]

The description of the video has alot more detail on the parts and different codes/numbers involved.

[@joeg7755]

Outstanding video, loved it! Question, these GMT400/455 vehicles will be around for some time to come. Once all the ABS units are gone from salvage yards and seller sites, will there be a way to upgrade/install from a newer ABS platform like GMT800 or 900? Thank you sir.

[@DrShock]

Thanks. I'm not aware of anyone offering a rebuild service for this unique ABS module design. I've also not seen anyone offer a retrofit from a later model either. I think this is going to be one of those facts that drive these OBS trucks necessarily having to be retired from daily driver status as they are going to become unrepairable with OEM quality parts very soon. Aftermarket parts for these OBS trucks are generally of very poor quality and fitment.

[@joeg7755]

@@DrShock Thanks for the reply. Not fair to the little guy that can't afford a new or newer used vehicle. Especially if the current vehicle is in good condition. You almost think that the OEM and government has gotten together to force everyone to by vehicles every 10 to 15 years. What a waste of resources as it has taken many barrels of oil to product the truck I have now. Especially if it only requires a module to be replaced.

[@frankyeilding2546]

@@DrShock The GMT400 is an iconic platform, people love them and their value is rising. I keep hoping the free market will provide a solution when some company realizes that people will pay for OE quality parts. GM isn’t exactly killing it financially, wish they would start supporting it again. They could make a killing on interior trim pieces and dashes alone. The Coverlay door panels for instance are terrible, it’s like they got right up to the job well done mark and just said “Nah, F it, let them eat cake!”

[@haccoon5458]

Thanks for asking this. My exact question to. If you find out any upgrade maybe you can share back here when you do 😊

[@TigerHoover]

The factory service manual should come free with the truck when you purchase the truck. Awesome video and thank you very, very, much! Where can I find an EHBU assembly for a 2000 silverado 1500? Ebay has a few but how do I know if that's a failed one?

[@DrShock]

Thanks, unfortunately you have to rely on a combination of the eBay money back guarantee and the sellers description. If the seller states the part is in working order, eBay will force them to refund you if it ends up not being _as described_ so no worries.

[@willyvn1957]

DrShock I understood from your explanation at almost the end of your video that I need an ABS with letter code S because the suburban 6.5TD is too heavy (3Ton), because when I reconnected the old ABS (electrically) I could work with the GM Tech2 again and the faint warning brake light on the dash had also disappeared. The reason why I have to replace the ABS is that I have the DTC code C0042 BPVM failure .... I could no longer bleed the brake system. Can you sometimes help me to find the correct ABS with letter code S because it cannot be found here in Belgium, thanks in advance

[@DrShock]

Your best bet with this kind of long discontinued part is eBay. I put some links in the description that you might check.

[@crawford323]

I just had a well known local repair shop refusing to work on my 2000 Chevy Express Van. I am now waiting on a scan tool to ping the ABS to help bleed the system. I , like you had to replace my unit with a salvage yard unit. My valve body was shot.

[@DrShock]

Yep, when they get to a certain age most shops won't touch them. Alot of these shops only know how to swap parts, not diagnose anything and have no older service manuals. Brittle plastic that breaks rather than disconnects, intense corrosion that can break the fastener during removal etc. All of these things cause shops to pass on your business after certain number of years has passed. Best is to handle it all yourself anyway.

[@crawford323]

@@DrShock What Scan tool code reader do I need for a 2000 Chevy Express Van? I followed your link and I believe eBay has done a bait and switch and led me to a cro123e which does not support the auto bleed function. Have you a fresh link to the Tech 2?

[@DrShock]

A Tech2 clone would be great. An MDI clone running the Tech2Win emulator would work too. That eBay link works fine for me, it's not possible to filter out the folks who misleadingly tag their listings with "Tech2" , but the Tech2s are showing up when I click it.

[@crawford323]

@@DrShock You are a good man Charlie Brown. I can not thank you enough for your expertise and additional effort to share your knowledge.

[@wierpkevin]

That was amazing, thanks

[@benkanobe7500]

Dr. Is this the K-H that none of the ABS Module Repair places will attempt a repair (I think due to the way you have to remove the top of the electronics)? I have tried to get someone to rebuild my K-H on my '96 GMC Suburban K2500, 7.4 Gas and not a single repair place will attempt it. The later one, 325, (is that what yours is) they do everywhere and offer a good warranty. I see you have listed it as 310. Hope that is what mine is as it is NOT a 325. Thanks. I am at 1:11.

[@DrShock]

This is about the EBC310 yes, not the 325. And yes, the 310 EBCM is completely *NON* rebuildable. The 310 BPMV used to be rebuilt by Kelsey-Hayes and sold thru ACDelco, but no longer. All new and reman parts discontinued by GM back in 2020. So the only repair route is salvage yard, which is why I provided quite a bit of additional identification info in both the video and alot in the video text description as well.

[@tysoncurrie7745]

I have the same issue with my 1996 GMC 2500 7.4L Suburban the anti-lock brake light is on and can't find anyone who will help me and I then saw this video, it gives a bunch of info but is still discouraging due to you not being able to get needed parts and having the expensive tech-2 or bidirectional scan tool that can do a ABS bleed or readout on trouble codes with these year trucks. It's going to get to a point where you can't find these in salvage yards and no replaceable parts at all. What are we suppose to do with repairs or replacement on a poor common faulty ABS module in the future? At that point all we can do is delete and bypass the ABS module completely which sucks because now the vehicle isn't operating as manufactured or designed to. I really hope somebody or a company makes their own parts in house to be able to reman these into a complete unit for us to purchase and then send in the core to be remanded as well, because this is starting to get scary on parts not being available and not made anymore and with the shortages on parts. It's a saftey issue if we can't keep our vehicles reliable on the road. 😥

[@awbjwc]

Amazing video! A lot of useful information. I am curious to as if I can use an ABS (brake pressure modulator valve) from a C series truck for a K series truck? I have a 96 k3500. The truck at the wrecking yard is a 97 C3500. Please help. Thank you!

[@DrShock]

The video description text has the part numbers by truck type spelled out.

[@davekibble3556]

After bleeding module, there is no need to re-bleed at wheel ends? where does the air in the module escape to? Also will the tech tool automated bleed work if the ABS light is on? Say for a bad wheel speed sensor. Thanks, I've got spongy and weak rear brakes brakes on a 96 K2500, after rear brake line leak/repair. hope bleeding the module will fix it

[@DrShock]

Bleed the calipers and wheels cylinders in the usual fashion. Then use the scan tool to initiate the ABS unit bleed procedure.

[@jamescole3152]

Wow what an in depth video. I have a 1998 chevy and the ABS looks identical. No way do I want to fix mine. ABS delete is what I want to do. I have a few questions. First are my brakes suppose to be weak? I mean I just went through all 4 wheels and put on all new brakes. On the front wheel calipers I notice the banjo bolts with the copper washers only has a tiny pin hole to let the brake fluid through. Add that to the masters cylinder springs that take all of my strength to bench bleed and I have to wonder why? I want to be able to lock up all 4 wheels if I so desire. Maybe the ABS is making the brakes weak? I really like this video so far.

[@benkanobe7500]

How did you test your replacement unit off of the truck? Did you just do the one test for resistance? Please explain as I purchased two units without the aid of Tech II and so it is crapshoot if they fit my Suburban (8600 GVW) with hydroboost. It would be nice to at least be able to test them prior to installation.

[@DrShock]

You can perform the first resistance test, on the pump within the BPMV either on or off the vehicle. But the second resistance test, and the voltage test, for the EBCM C3 connector have to be performed on the vehicle. Unfortunately there is very little you can do to test either the EBCM or BPMV on the EBC310 series off the vehicle. It would have to be a plug and find out if it works situation. And not knowing what vehicle the ABS unit was pulled from, next to impossible to identify and determine if it's correct for your vehicle. I try to improve my odds in these situations by only pulling/buying salvage parts from a crash vehicle, so at least I know it was running before scrapped vs someones _project_ they gave up on. If your Suburban is a 2500 though, you would be _lucky_ in that it would use a unique combo valve with code "S". But a 1500 could be any of two different EBCMs that both share the same BPMV and both use a code "A" combo valve. You have to know the parts history, what it was pulled from, to be sure of fitment.

[@benkanobe7500]

@@DrShock Thank you. Perfect detail and Factory info as always. My truck: 96 GMC K2500 Suburban, Auto, 7.4L Gas, 8600 GVW, Tow package with locking diff. Not a bunch of my truck at the salvage yard...

[@DrShock]

Yeah tough to find, but easy to id given it's a Suburban 2500 (C or K). You just need to verify that "S" code on the combo valve. Your original should have it, if it's the original. ;-)

[@stickytireproductions7516]

Hello @dr.shock my combination valve is leaking from one on the bleeders on the side. Can i replace just that piece or will i need a new combination valve?

[@DrShock]

GM didn't service just that piece by itself. There may be a seal or such in there, not sure. I would replace the entire combination valve if I were doing that repair.

[@pedrorodriguez-qh5kg]

Fantastic

[@dennisfrank1974]

Great video I recently bought a 95 in great condition not knowing it had obd1, so I don't have a scan tool for it. the abs light is on and I thought I could just go to the local parts store, spend a couple hundred to fix an abs systen I don't need, but no parts, I should have bought a Ford. I have been driving for 50 years with out abs, but I have one now that needs fixed, if I can't get the parts needed I will have to find a way to eliminate it. Mine stops ok with normal pedal presure and travel, but after I stop I can push it to the floor. I can hear what I think is the abs pump. When your pedal went to the floor how did you determine it was the bpmv and not the master? I want to keep this original, but if I can't get parts I would feel much safer with out abs.

[@DrShock]

Thanks, I didn't mention anything in this video about a pedal to the floor situation occurring. I mentioned you can suspect a BPMV when you have a pulling condition, to the left or to the right, that is otherwise not indicated by the usual suspects (front hose, caliper, etc).

[@mitchmcbane]

You showed a test drive. And talked about streeing wheel pulled to the left. But you did not mention, what's happens if you did drive test and it did not pull hard to the left but truck still has ABS light on..

[@DrShock]

A pull is related to a sticking or stuck solenoid in the brake pressure modulator valve (BPMV) module. It's going to be mechanical and will not trigger the ABS light at all. When the light is on, it's something electrical or hydraulic sensor detected and that's usually going to be with the Electronic Brake Control Module (EBCM) and give a code for a scan tool capable of retrieving ABS module codes.

[@jamescole3152]

Genius .

[@kiddbrother3]

I have a problem like a bypassing master cylinder I changed the master cylinder 3 times! I see there is a dump valve (310 Kelsey hase) '97 GMC c1500 where it is a dump valve located ?

[@danielstarkey9269]

I have 97 k2500. Getting a “C0052 rear dump solenoid circuit open”. But i also have a very soft break pedal. So is this electrical or is the dump valve actually physically stuck open. If I separate the two, can i use a magnetic to open and close the valve to get it cycle. Or is the valve statically open and the solenoid closes it. Which i hope, cuz that would be electrical in the module.

[@DrShock]

There's no such code in the GM service manual. Perhaps a typo and you meant C0252? If so, which has the same description, all of these EBCM codes C0241 - C0254 are circuit related. If the problem is not found in the wiring harness or connector ends, then replacement of the BPMV module is required.

[@scottm7341]

First, thanks for a great vid. I have a 97 K3500 with a warmed up 7.4L with headers and a cam, so I swapped the ecm to a more capable 0411 from a 2001 5.7l L31 van, and had it tuned for my engine. Now I'm having trouble with the abs. Isn't it normal for a Chevy abs unit to make a little noise when you first turn on the key? Like it's going through a little startup routine. Mine is not doing that any more. But I'm also having trouble with the normal 2 man bleeding routine - i'm getting no flow at all through the abs unit, like a valve inside is shut. Is this related to the ecm swap somehow?

[@DrShock]

Thanks, the ABS units on these later model (after 1995) OBS trucks cannot be manually bled. You have to use a Tech2, or equivalent bi-directional, scan tool to actuate the integrated automatic bleed function. I did another video on this procedure earlier - kzbin.info/www/bejne/apesnoiepbx8mrc

[@scottm7341]

OK thanks! My neighbor loaned me a snapon 2500 scan tool to play with, and it tells me the abs is 'disabled' but also says the truck is still drivable. I'm waiting for a reply from the ecm tuner to see if they might have turned the abs off.@@DrShock

[@dieseldog2649]

I messaged you earlier tonight about a situation with the same ABS box on my 97 c3500 dually 6.5 turbo diesel. I asked you about the pin on the lower bleeder that faces the engine missing after Auto bleeding it. I found this video and watched it. At 1:02:57 of this video you said that the one pin that faces the engine sometimes is not visible and that is common. That is the one I was telling you that was missing on mine. What I'm curious about is before I ran the tech2 auto bleed that pin was pushed out like the other one you showed. After running the auto bleed it was not visible almost like it sucked up into the box. Is that what happens or am I misunderstanding how it works. I appreciate your help

[@DrShock]

I've not seen one _missing_ the center pin entirely before, but I have seen them in _slightly_ differing depths. I would speculate that these move to facilitate auto bleeding of air. But they can become corroded and inoperative in salt belt areas. Especially if the black rubber boots that protect them are missing. You might remove the boots and observe their operation during an auto bleed procedure to confirm there is no brake fluid escaping.

[@EATSLEEPFARM]

Hello im working on a 1998 Chevy Tahoe. The brakes are locking up on the front passenger side. Thought it was the caliper as it wouldnt press back in so we put one on. I noticed during bleeding that fluid would not come through the bleeder everytime the brakes where pressed. I told him not to drive it but he insisted and the brakes locked up again. The lines seem fine. What outside of the model could cause this just on the one side? The master cylinder and booster seem to be operating fine aswell. Thanks for any help or tips

[@DrShock]

You have to diagnose each component of the brake system individually to see where the fault is. There is no single failure point for the symptoms you describe. It also can be very expensive to fire the parts cannon at a problem like this as well, so the time invested in diagnosis could actually end up saving money. I would start at the master cylinder checking pressure and correct operation, then the hardlines for obstruction, then the hoses for same or collapsing, then the calipers. When all else fails, it's likely the ABS module as we showed in this vid.

[@EATSLEEPFARM]

@@DrShock thank you fir the reply. Somone else said it was the calipers and I just changed them. This is when i noticed the passenger side was at fault and it still wouldnt compress even after the master cylinder was unhooked. But would once you cracked the line at the caliper.So its gotta be something im nlt seeing in a line or the abs module. Whats the best way to check the lines themselves if nothing is visual? Thanks again fir the reply

[@DrShock]

It's difficult to say remotely over a comment board, but if you had _back pressure_ and then that was relieved when you opened the line closer to the caliper, but did *not* relieve when opening the line at the master cylinder, I would be suspecting a hard line or hose obstruction as a start followed by ABS unit. Again, anything over comment board sight unseen is going to be wildly subjective suggestions wise. On hoses you can visually inspect them for being collapsed internally. On hard lines it's only a painstaking visual inspection for dents/crimps externally.

[@EATSLEEPFARM]

@@DrShock Completely understand. It is almost impossible to guess the exact problem through talking and not visually seeing it. Just wanted some direction and you’ve given me that. Thanks

[@stephenyork8857]

How are you communicating to it if the black box is not the one that is to your vin numbers

[@DrShock]

Not sure I'm following your question as the EBCM is NOT a VIN coded module like say a PCM or a BCM. Instead, it is tied to the powertrain and brake options as I went over. GM encodes the EBCM software to support different brake and powertrain combinations in the era this video covers. The EBCM is the black plastic box at the top of the EHCU assembly. If necessary a GM Tech2 scan tool can be used to learn the module to a VIN, that's it's purpose. But for a complete EHCU replacement that's not what we use it for, instead we use it to command the BPMV portion of the EHCU to perform the automated bleed procedure to vent out any trapped air. The EBCM _cannot_ be reprogrammed by _any_ tool. You have to match them _as built_ originally. A bi-directional programmable scan tool like the GM Tech2 is _required_ when doing GM ABS module replacements of any type as there's no other way to identify the EBCM firmware version, or to initiate the BPMV auto bleed.

[@stephenyork8857]

Thanks where can I get a tech 2 tool

[@jamescole3152]

"a retaining clip to keep it from coming off" I looked at that loop and thought it was an amp meter lol.

[@wundabread101official2]

Is there anything else I can do to bleed the abs system.. I just swapped out mine on my 98 k1500. And it doesn't seem to be putting it to the rear brakes at all

[@DrShock]

For the model years this video covers, you need a scan tool to actuate the automated bleed process - kzbin.info/www/bejne/apesnoiepbx8mrc

[@nauju1998]

I have a 1998 GMC Sierra C1500 that has the abs light on, but when I try to read the abs codes it says that there are no codes, what could it be?

[@DrShock]

Are you using a bi-directional scan tool? A regular OBD2 code reader typically can’t access ABS or SIR module codes.

[@nauju1998]

@@DrShock I got access to a high end snap on scan tool which does all of that and it didn’t show any codes

[@DrShock]

If the lamp is lit, you have a code (presuming there's no damage to the instrument cluster flexible circuit board). If your snap-on has both a generic OBDII mode and a OEM specific/proprietary mode, I'd try the latter configuration set to GM.

[@MyLifeThai371]

@@nauju1998 Were you able to eventually read it?

[@eduardosuarez5617]

Mine fell the first test, the brushes of the motor are fixable??

[@DrShock]

The BPMV pump motor is not serviceable separately. Best route is an NOS one (long discontinued by GM) or salvage yard replacement.

[@eduardosuarez5617]

@@DrShock thanks

[@AngryBeardFace]

Great video!! Thanks for taking the time to break this down so thoroughly. I am having an issue with a 1996 2 door Tahoe that I cannot see the ABS system at all. I have tried numerous tools and it looks like the whole abs unit is dead. I have checked all fuses and wiring. All are good. I swapped out the EBCM with another unit from a same year truck. (after watching this video I need to see if it is compatible) and I am having the same problem. Is it possible I could have 2 bad units in a row?

[@DrShock]

Thanks. If you're not getting any communication at all you'll want to verify the communications bus wiring is intact. I would say it _highly_ unlikely odds wise to have two bad units in a row so sometimes it's just that _Occam's Razor_ applies. ;-)

[@AngryBeardFace]

⁠@@DrShockthanks for the quick response, any suggestions on testing the serial bus wiring? I’m an noticing that the ABS light illuminates, and then flickers off for a moment and back on. So quickly, if your not watching it, you would never see it.

[@AngryBeardFace]

@@DrShockI did the ABS systems test in the 1998 CK Service manual this morning and everything seems to be checking out from a power standpoint.

[@DrShock]

You'll want to go thru the service manual checks for the serial bus wiring (since your original complaint was no scan tool communication). It's possible for the unit to be powered still have no communications.

[@AngryBeardFace]

@@DrShockI did the Serial bus test and I have 5v on the data line. According to the CK manual it appears to be shorting to something that is giving 5v in the Key on position and also in running condition. It should read zero V. If the unit abs unit was bad, could it short the data line in this manner? I am debating on running a temp serial line to the OBD2 port and the abs harness. Do you have any suggestions?

[@mikegarcia1117]

Hello there I have my front brakes on my truck locked y replace master cylinder and calipers the brakes still lock I assume is the abs system any tips on fixing this problem

[@DrShock]

Unlikely to be calipers because they do not fail in pairs simultaneously, only individually. So you're checking all the components that are shared by both front brakes. You have to do diagnosis and determine the failure, as this could be very expensive to resolve just throwing parts at it. Could be any number of things. Need to pull any ABS module codes first with a scan tool capable of reading those. That might point you in some direction. Check all front brake hard lines for damage/restrictions, check front brake hoses for being collapsed. For the pads to not release, something is preventing fluid pressure from subsiding after the pedal is released.

[@mikegarcia1117]

Thank you for the reply I replace the lines and master cylinder still locked I’m checking the abs system

[@Hitman-ds1ei]

I'm curious as to identifying the fixed orifice unit from the variable orifice unit, information is thin on the ground for this in Australia

[@DrShock]

I've not read anything about any such orifice differences with regards to the EBC310 4WAL unit used in the GM OBS trucks. The BPMVs used in this era ABS technology were built uniquely to each truck model and brake/power train option. Hence why there are so many GM part numbers.

[@Hitman-ds1ei]

Mmm interesting as my 96 C model comes up with fixed orifice in tech2 but my 98 K model doesn't

[@DrShock]

Curious, which Tech2 special function / test are you seeing that verbiage on? I'd like to look into it some more.

[@edberry925]

Educational Tutorial. The take for me is that I will need a used unit. Following your guidelines for my 98 K2500 Suburban 7.4 4L80E. There isn’t anyway of knowing what your getting used unless there was power in your salvage vehicle , is that correct? Was that your situation with the one you purchased.

[@edberry925]

To add can the unit be manually bled or only with the Tech2?

[@DrShock]

These 95+ years need a scan tool, Tech2 or equivalent bi-directional, for the BPMV bleed procedure. You may find a modified, or non-stock, vehicle at salvage. But presuming it's still stock (because these 4WAL ABS units were _never_ available via aftermarket suppliers) just knowing the RPO codes from the glove box should suffice for a match.

[@edberry925]

@@DrShock Thank You for the prompt response.

[@stephenyork8857]

I have a 1998 chevy k1500 5.7 z71 how do you vin the other kelsey hayes abs module board

[@DrShock]

The EBC310 series EBCM is *not* a VIN learned module because it is *not* programmable, everything is hard coded calibration wise. So you do have to match the EHCU part number with the RPO of the brake type and original powertrain as, again, the EBCM & BMPV valve programming is _hard coded_ per part number to specific RPOs. So a particular part number EBCM is only programmed to control a particular part number BMPV, for example. I have these RPO and part numbers in the description.

[@stephenyork8857]

@DrShock you got any contact info I

[@stephenyork8857]

@DrShock when I try to put another abs module on truck I can't communicate with it because it dosnt have my vin number it has another one on it

[@DrShock]

Again, for the OBS truck years that this video is about, the EBCM does *NOT* have a VIN association. Later year trucks would have that, but not the older design trucks. I should point out that old body style (OBS) GMT400 and new body style (NBS) GMT800 designs overlapped from 1999 thru 2002. NBS trucks do NOT use the EBC310, instead they use the EBC325 which will be visibly different than what I went over in this video. So if your truck is in that model year range, it would have to have the EBC310 EHCU that I showed in this video, otherwise this video won't apply. I can't comment on the NBS design, as this video is only about the older type.

[@stephenyork8857]

@DrShock I have the jb5 it says I try to put jb6 on mine and I couldn't bleed the abs module couldn't communicate with ir

[@raulalmaraz218]

Dr. Shock, thanks for this video- do you have a shop and if you do where are you located?

[@blue4980]

Whats the co281 brake light circuit?

[@mauropedraza3969]

Can you use that tech 2 on a 1995 gmc sierra 1500 to do an auto bleed on the brake system?

[@DrShock]

You can if it has OBD2 for the Tech2 to communicate with it. 1995 was a transition year for OBD2, most vehicles will still have OBD1. The Tech2 will come with both an OBD1 and OBD2 adapter, but as best I recall the automated bleed was an OBD2 feature only.

[@zachwilson9608]

Hey sir. I don’t have a power bleeder can I just bleed normally?

[@DrShock]

You will have to have a Tech2, or similar, bi-directional scan tool to initiate the auto-bleed of the ABS modules' BPMV. But you can bleed the rear wheel cylinders and front calipers in the usual way if you don't have a power bleeder.

[@robertquinn6488]

Thank you for the video it was very helpful. I have a question for you. You said diesel need to have a function test done 4 time to bleed the air out of the new system. I have looked online and have not found any information. Do you have any information on a ABs function test? My truck is 1995 C3500HD OD1. Thanks Robert

[@DrShock]

That 4WAL automated bleed test would be in the Tech2 scan tools special functions menu, if you do not see it there then it may not have been available until 1996. 1995 was the transition year to OBDII so some tests may not have been available until later. Here's a link to another video where I go over actually performing this test - kzbin.info/www/bejne/apesnoiepbx8mrc

[@robertquinn6488]

@@DrShock My truck is 1995 C3500HD with a 6.5 diesel OBD1 with the 4WAL. Will the TECH1 work with OBD1. Is there way of bleeding the system manually? Thanks Robert

[@DrShock]

You can use a Tech1 tool with OBDI, or the Tech2 with one of its included adapters for OBDI. The earlier units did have a manual process, but I'm not familiar with it. Would be in the older year GM service manuals I'm sure.

[@robertquinn6488]

@@DrShock Thank you

[@robertquinn6488]

I hate to bother you again. I have completed steps 1 -12 all my grounds are 0.4 to 0.7 oms and my voltage on C-3 is 12.5 to 12.6. The codes I have now are 22' 23' 27' 28'. I had found ABS module on Ebay. I had cleared my code and plug in all the electrical connection's to check for codes before connecting the brake lines. I ended up with a code 35. Thinking I had bought a bad module. I had bought another one from a junkyard. I had repeated the same steps and now I have a codes 23 and 26. Do you thing all of the module's are bad? I have all so checked grounds at all wheel speed sensors and transmission sensors and all read between 0.4 to 0.7 oms. I am thinking the ABS modules could be bad. My ABS light does not come on to show codes. All of the codes are showing up after I clear all codes by unhooking the battery cables and scan for codes. As soon as I reconnect the battery cables the codes show up. I don't even have to start the truck. Only turn the key to the on position and the codes show up. I am thinking the two modules I have bought. The people who sold them to me may not have realized they are bad if the didn't have an ABS light on the dash? I am trying to make sure I am not over looking anything. Can you please let me know what you think? It would be greatly appreciated. Thank you Robert

[@alexurzua4728]

Was the candi module connected in this video

[@DrShock]

No, this 4WAL ABS module is a pre-CAN era one from the 1990s. So no CANdi needed.

[@alexurzua4728]

@@DrShock Iam looking for a tech 2 to diagnose 1991 to 2007 gm cars and trucks. Can I get by with the tech 2 with no candi module.

[@DrShock]

Everything at GM went CAN by model year 2008 afaik. But I think you'll only get thru 2006 trucks, as I believe CAN started in 2007 on the new truck architecture that launched that year. For cars, it depends. I think Corvette went to CAN in 2005 though. A few Cadillacs went earlier too. So cars wise I think you should presume 1991 thru 2004 to be OK, but hit or miss starting in 2005.

[@alexurzua4728]

@@DrShock do you think I could get by with a clone tech 2 with candi module and all the adapters.

[@DrShock]

WITH the CANdi yeah, for that year range would be fine. But you asked about w/o the CANdi initially. You'll need an MDI insead starting in 2008. To find what year/model dropped Tech2 support use this GM PDF (they took it down but it's still on the Wayback Machine) - web.archive.org/web/20201025200221/www.genuinegmparts.com/pdf/positionstatements/vehicles-supported-by-GM-scan-tools-reference.pdf

[@willyvn1957]

This is the data of the original ABS module BPVM part number 32976 EBCM 4WAL Version ID: D7811TJP Combination valve is marked with the letter S Can you help me to get the right working ABS for my Suburban 1997 6.5 TD? I had bought a Refurbished on ebay in the USA but upon delivery I already saw that the BPVM had a different number and when I used the 4WAL version ID it was GCK36J and I could not connect to the ECU. I could disable the ABS but then I can no longer work with the GM Tech2 because the ABS connects to the ECU. That is why I am sending you the details of the original ABS that could connect to the ECU. Thanks in advance

[@DrShock]

The BPMV (brake pressure modulator valve) assembly is a shared common GM part number by all the trucks except the 3500s with RPO JF9 brakes. So you likely are OK there (the Kelsey-Hayes numbers on the parts themselves are not documented anywhere so not very useful). On the combination valve you could just reuse your original if you got a different one in the refurbished unit worst case. There are only two EBCM units for the non-3500 trucks. So you have a 50/50 shot of having the ideal one. I would still expect communications with the wrong one, just operational issues. Is it correct that when you connect your old unit communications are possible, but when you connect the refurbished unit there are no communications? If so, I would return the refurbished unit as defective and explain to the seller that when its plugged in your ECM/VCM communications are being interrupted. These technically cannot be rebuilt, so _"refurbished"_ here cannot mean anything more than a cosmetic cleaning unless the seller explicitly states that they road test each unit they sell.

[@willyvn1957]

@@DrShock So it is indeed correct if I connect my old unit I can communicate with the ECM/VCM I also wrote to the seller but only got an email back that the software must also match mine and if I did not agree I had to return it, that was not the case so I have already sent them back I only received them yesterday (9/17/2024) and today (9/18/2024) I have already returned them because after the last email via Ebay there was no response from the seller. With the ABS that is now temporarily mounted I can communicate only with the EBCM but not with the ECM/VCM which also has the 4WAL Version ID: GCK36J .... the Suburban brakes better with this unit but not as it should the ABS always activates when I use the brake. Here in Belgium I can't find this ABS unit so I wonder if I will ever find a working one because most sellers don't have a clue when I say it has to be a 4WAL Version ID: D7811TJP, .... they don't even know what is meant by that

[@DrShock]

Have you tried doing an automated ABS bleed on the original unit using a Tech2, or similar, scan tool? Sometimes performance issues on these units can just be the result of entrapped air.

[@willyvn1957]

@@DrShock I also did that with the original unit with the GM Tech2 but I kept getting the code C0042 = BPVN replaced .... what I have now also noticed is that my odometer does not work correctly when driving 80 km / h then I am actually driving 62 km / h and calibrating the tires does not help because this unit does not connect to the ECN / VCM which ultimately also controls the odometer ,

[@willyvn1957]

@DrShock As a last resort I could try to place the combination valve marked S and the EBCM from the original unit on the now working BPVM but then I would have to renew those 4 bolts and those 2 parts (on the parts diagram in service book no. 13) of the combination valve or take the risk of reinstalling the old one , I don't think it will work safely then so the only option I have is to find the right unit

[@alvinomartinez6549]

Will a control module from a 1500 will work for a C3500???

[@DrShock]

No, differences in power train combos and weight ratings drove differences in ABS requirements so GM had to develop different parts for the 3500 series brakes. I have all of the different combinations listed in the description.

[@alvinomartinez6549]

So I should only replace it with the exact same year and model for the EBCM?

[@DrShock]

You could use either a C or a K 3500 truck. I would aim for the same year or higher thru 2000 (they were still making OBS HD trucks for a bit past 1998). But if you're in a pinch and no good salvage yard selection of 3500s, lower years of the same part number should work too.

[@alvinomartinez6549]

@@DrShock will a 99-02 Chevy express 2500 be workable with the C3500?

[@DrShock]

The G vans use a different ABS system than the C/K trucks, so the programming inside the module is going to be different. You might find what you're looking for on eBay tho.

[@briananderson3801]

Hey doctor, how much is this unit ,the whole thing brand new and does it only come from GM?

[@DrShock]

The complete units were only ever sold by GM, but now discontinued. They are not rebuildable either. The video goes over the individual part numbers that will have to be sourced separately via NOS or salvage, depending on the repair. Links in the description.

[@briananderson3801]

@DrShock ok thank you very much I appreciate that have a great day

[@saleh5448]

I have question is there any different between 96 and 99

[@DrShock]

This design was only used on the old body style C/K trucks (OBS) and G vans. So 99 would only be the same for C/K SUV bodies. And for G vans it was the same thru 2002. But since the pickups went to the new body style (NBS) in 1999, there are no compatible parts - totally different ABS design introduced in 99 pickups there. SUVs changed in 2000, and G vans after 2002.

[@saleh5448]

@@DrShock thanks for responding I want to buy used ones so my truck is 96 Yukon 2 door 4WD what should I look for?

[@DrShock]

There's links in the descriptions for the ones I went over. Basically 1500 or 2500 or 3500 all are different. Aim to pull from the same model so a 96, 97, 98, or 99 Yukon or Tahoe.

[@saleh5448]

@@DrShock well I did find used ones no communication with ABS so what do think the problem ?

[@DrShock]

No comms from scan tool? Obviously wiring harness issue, you'll have to debug where the short or open in the communications wiring is located from the OBDII connector under the dash out thru to the ABS module under the hood.

[@jamescole3152]

Ok now I can turn the hood light off. I am learning.

[@joebatta8779]

Solenoids?

[@DrShock]

Possibly, though more likely the EBCM. These early ABS design BPMV units are not rebuildable so have to be replaced as a complete assembly.

[@loveofchrist5808]

Great video boss but I have a question is this the same type of equipment that’s located underneath the passenger seat outside the chassis on these GM Avalanche oh and by the way I have four Chevy avalanche and to have the brake and ABS light on is that what we’re talking about? I also have another question I know I’m full of it ha ha ha ha ha but you got a manual and a scan tool it said General Motors on top of the scan tool in a manual where do you get that kind of stuff never been that familiar with any of that stuff like I said before I want to get my first scan tool and I want to make sure I get the right one so can you help me with these two questions I would really appreciate it sir thank you and God bless you I’ll be waiting for your reply✝️✝️✝️

[@DrShock]

There are links in the video description to find the tools I use in these videos. This particular video is very specific to the years and models in the title. The later ABS module designs are quite different.

[@loveofchrist5808]

@@DrShock thank you thank you so much for responding to me, you don’t know how much this means to me I have talked to so many techs here on KZbin none of them none of them will respond to me a lot of them want to sell merchandise and want me to watch their videos which I have been doing but what’s sad is nobody wants to help out each other. But you sir you are a gentleman and a scholar to the industry I really do appreciate your response God bless you and I pray to Jesus Christ to bring you lots of love peace and prosperity for your family and friends and thank you so much for responding to my questions means a lot to me ✝️✝️✝️

[@loveofchrist5808]

@@DrShock I learned a lot from you and I do plan on donating just let me go get my credit card and I’ll sign up thank you for the information and thank you for teaching me a lot lol God bless you once again ✝️✝️✝️

[@loveofchrist5808]

@@DrShock and I don’t mind donating to you because you actually responded but all these other guys they just want you to buy their merchandise or donate but they never respond to you they never even say hi or nothing I don’t wanna be recognized I just want to learn something from the videos that’s what’s most important. So please keep doing the great work you’re doing and God bless you✝️✝️✝️

[@patrickjohnson7801]

WOW, can you please make a video on how to remove all this stuff and put it in the trash.

[@DJJDSKREWED]

any info on deleting this system entirely?

[@mikem5475]

Delete the obsolete abs system if possible for your situation. The issues will continue and contribute to the destruction of the truck

[@DrShock]

That's a *really* misinformed suggestion. As an engineer I'm here to tell you ABS technology saves lives and *prevents* destruction of property. Anything claimed to the contrary is flat out fake news. Repairing the vehicle back to factory specifications to maintain a safe and reliable transportation tool is the only path. Full stop. Fix it right and safe, or don't drive it until you can. Part of why I make videos like this one, sharing alot of deep technical details, is so folks can do exactly that themselves.

[@mikem5475]

@@DrShock HAHAHAHA you have the money for it!! The scan tool, the new parts, all that

[@coolhanddruid]

@@DrShock Oh bs, just a few years earlier and there was no abs, plenty safe to drive, and lol to your needing to throw away some stupid screws cause they were torque to yield

[@justpray365]

@@DrShock I normally would agree with that statement. However, GM and other parts suppliers have chosen to make that decision for us. They saw fit to discontinue the much needed parts to keep these vehicles in factory condition. If it was of paramount importance to keep these vehicles in factory fresh condition, then the government should require that parts needed for safety, such as brakes, be made available. Instead, the government decided to award people to crush used vehicles and make it much harder to find acceptable used parts on this still usable but aging platform. I decided not to fight the system and just unplugged it. Power bled the brakes and now my truck will stop before I run over innocent children.

[@frankyeilding2546]

@@justpray365 Dr Shock is awesome & I love his videos. I agree with that ABS is a great safety feature. However your point is valid. Many are left with no choice when parts fail and they can’t find a substitute.

[@1969camaro]

Next time dude you just gotta get to the point