S10 4x4 Problems - S10 4wd Not Engaging Front Diff

[@NECARLOG]

Thanks For Checking out my Video. Please subscribe if you like the content and feel free to comment with any info I missed or anything that may be incorrect.

[@daddyfixit631]

Its not complicated. Its a few parts. I've worked on them and the most common problem is the vac line on the drivers side fire wall dry rotted. Guys check your main vac line plugged in the drivers side fender. There is a nipple coming from the inner fender on top. Check this for proper system vac pressure(source). As he stated button. Check. If the button works but it's flashing and you have proper vacuum on the system but not at the bulb under the battery with the cable then here is the problem, there is a selonoid switch almost in line with the buttons on the firewall under the hood that switches vacuum on and off to the bulb and cable under the battery. This sticks due to bad vacuum lines sucking in moisture from outside air up the lines and to the switch. I've been able to fix these by cleaning with wd40 and a voltage probe. Don't replace the actuator or anything else to #1 vacuum system source is good ✔ #2 4x4 vacuum from fire wall switch is switching with button ✔ #3 line from switch on firewall is supplying all the way to bulb and cable without a problem like dry rot or crimp or disconnected. Vacuum lines usually fail after work has been done. They are dry rotted then pushed or leaned on and still may or may not work all the time and pull in moisture. Replacing the bulb and cable or actuator motor is usually unlikely the problem. It's more often the simple things like vac lines and moisture. Hope that helps someone.

[@joelbecker3122]

Hello, I replaced the bulb and now the axle tries to engage but there is a loud pop from the front axle when it is engaged and under load. Is this that slip collar being damaged? Is that an axle rebuild?

[@kenhutcherson6082]

My first vehicle at 15 was a 85 s-10 blazer with the manual 4x4. Always worked. When I turned 16, a death in the family got me into a 95 Jimmy with the electronic 4x4. It would always go into 4 Low but when you would push 4 high I would hear the relay come on and the light would blink and then it would automatically go back to 2 wheel drive. Got an estimate of $1200 to fix it so never bothered. This was 1999 when I got it. I missed the 85 blazer even with the pitiful 2.8 carbed engine.

[@davidherd2598]

I have a 2002 jimmy with a 4 button 4x4 will that button work on my 2000 gmc jimmy which has 3 buttons

[@clarksavage5611]

yes sir i have 01 s10 have replaced the vac switch on transfer case and the cac can under battery / no discernable vac hose leaks nothing works?

[@Mike_The_Hog_A_Nator]

I have an 02’ Blazer ZR2 that is clean as hell. No rust, etc. but it eats the 4x4 Actuator. I just swapped out my 5th Actuator at O’Reillys (Lifetime warranty) since the past year! The diaphragm on the actuator keeps splitting & I have no idea why... It takes no time to swap out but it got me stuck again when I needed 4x4! Bad design & again. If you look under my hood? Everything looks brand new, like factory. I thought maybe a little rust was under there but it’s clean & I haven’t a clue why that diaphragm keeps splitting. It splits in different areas each time also. But as long as it’s under warranty? I’m a keep bringing them back. At $60ea they should last but I haven’t had 1 last longer than a few months. I use 4x4 once a week if not more on the Ranch

[@larrybrenner4379]

Perhaps it is the O'Reillys part that is manufactured in China or India. I don't find taking the battery out each time that fun. I had a Buick with a bad motor mount; replaced at O'Reillys and had an awful time installed, had to file out mounting holes and torgue rubber off to the side. It should have been simple. Mount was made in India. But the price was good. If I can now I purchase AC Delco for my parts work and fit well. My Blazer is a 99.

[@robertleftwich1122]

Mike Hog A Nator is there a range of vacuum that needs regulated?

[@buckshotbill1127]

take a good look at the diaphragm next time chances are your maybe leaking some kind of fluid on it. maybe battery is boiling-over/venting or its icing over from water and ripping in the winter. least you know you have good vacuum lol.

[@12345Flipside]

I have a 1999 Chevrolet Blazer Vortec 4.3l V6 4WD 4-door with the 4-button switch... My 2 HI, 4 HI and AUTO 4 WD works fine, but not the 4 LO. There is no click and the light on the button is only blinking. What is the problem?

[@jeffeby6030]

My front differential on my 2003 Sonoma seems to be locked in the off position. It will not pull out, even manually. Any suggestions?

[@MegaBedrock1]

I got a 95 blazer 3 switch, I replaced the actuator with a pull cable, and I still can't inenage the 4x4, did u have to cap the 3 vaccum lines?

[@jeffwoods9986]

I have 2 LS (S-10) style 4X4 Blazers, this push button engagement system just plain sux ass. Lol

[@SnubZero442]

Hi i bought an actuator and actuator cable for my 99 Jimmy and i tried to replace it but i have a problem. On one end of the actuator cable it goes to the actuator under the battery tray that was easy to change. But at the other end it has a fitting that has to be unscrewed and that is my problem. It was so seized that it didn't even thread out instead it snapped. So i need to know what that thing i broke is called. It has 3 bolts to take it off. Thank you in advance

[@danielreeder3113]

On the 98 I just bought the wire coming from the front differential has been ripped off. Where does it lead to on the drivers side fender? I don't see a connector it might have been ripped off beyond that. Does it lead into a bigger part of the loom? Now that I saw this video I atleast know where to start my search for it, I've been looking for wire underneath the truck. The kid i bought it from said it was hung up on a dead fall an he just cut it.

[@tonyburke8441]

Well that pull cable system work on a 99 GMC Jimmy for the four-wheel drive

[@Thomas-ts2gl]

Anyone heard of this before.. 1990 jimmy has vacuum to the actuator when in 2wd and in neutral and no vacuum when it is in 4wd high or 4wd low. The transfer case is engaging the front drive shaft in 4 high and low. Could it be the wrong vacuum switch.. opening and closing backwards or something in the transfer case? Thanks

[@Mike_The_Hog_A_Nator]

My 02 Blazer ZR2 4x4 was working fine until I just got it back from Transmission Shop for a Rebuild & now my front diffs won’t engage. I’m assuming they switched up the vacuum lines on tranny. I have a new actuator under the battery & just ordered a new Vacuum Switch (the one that mounts on trans case). I pulled the current switch & it looks good. No fluid, etc.. in the switch or lines. My Sun Shield snapped under normal driving conditions & the shop said told me the 3-4 clutch pack was burned up. So I just went for a full HD Rebuild. My only guess is they got the vacuum lines messed up. I can hear & feel the trans case going into hi & low, just no front lock up

[@user-gq3fw2kp3w]

Mike Hog A Nator did you figure it out? I just bought a zr2 and it’s making the sound of engaging but it doesn’t lock in

[@brandoncuozzo6030]

Please let me know if u figured it out. I’m in same position. An before I got a chance to try to figure out why front tires won’t pulling, now I got a loud roar on front passenger side an sounds to me like the front diff is halfway engaged an making the roaring noise. Can put it in 4hi and noise gos away. But still front end not pulling.

[@ZoeyTheGSP]

@@brandoncuozzo6030 did you ever figure this out? having same issue on my 2000 3-button blazer

[@scarakus]

Replaced the vacuum actuator (diaphragm was torn), 4hi light comes on, but goes out after some time, press it a second time, sometimes holding it down for 5 sec, light comes back on... what do you think, intermittent vacuum leak, or bad vacuum valve on transfer case? no fluid present in hose... Last one i had, someone had pulled & clamped the cable, leaving it engaged all the time...

[@randysprague2321]

Cabal stuck front diferental how do I free it up also the vacuum line to the cabin is broken at the roamc casing how to replace it

[@bryonbaker5349]

So if I wanted to convert my Sport utility 98 Blazer to the 3 button automatic 4 wheel drive( 4 button if you count 2 wheel drive) from my now blown motor 99 Blazer LT Id need the transfer case, wiring harness for it ant the wiring harness for the dash? I actually want to swap my whole interior over anyways because the LT has heated leather electric seats.

[@kristophermiller3703]

Do u have any idea of the vacuum diagram 2001 gmc Sonoma??

[@louisgallaher5487]

i hear my transfer case engage but the front tires are not spiing when im on 4 low,,, what do i doi bought a new diaphram

[@NECARLOG]

The diaphragm is under the battery. test to see if you can pull the old diaphragm and move the cable to the front diff and test the vacuum line for suction. The cable to the diff can be frozen the diaphragm could be bad or there is no vacuum to the diaphragm which can be caused by many things

[@brandoncuozzo6030]

NE car log how do you test for vacuum leaks? What’s the best way to go about that?

[@fluffygamer1190]

I have a question on my blzer if i hit any of the 4x4 options the lights just blink i dont hear a click from the computer. Am i supposed to even if it doesnt engage? I ask because i do hear it when i hit 2wd again and it engages

[@drewfoy]

Try pulling the module on the passenger side floor under the plastic panel next to where right foot would be. Get a wire brush and go over the contacts then put it back in. I have a 2003 s-10 Zr2 pickup and this worked for me 7years ago & to this day has not failed again.

[@randyfera9228]

I have 2000 s10 sounds it's not fully engage without hitting 4hi button i hit button & gauges went crazy fuel/battery/volt battery light came on auto trans position don't work fuses blown not sure if it's tech shorted out any help

[@billynicgorski1]

I removed the battery tray on my 2001 blazer and the diaphragm is engaging and pulling the cable ..still no 4wd. Any help? ty Billy

[@lord1490]

Got a 97 blazer. Issue i have is I'm stuck in 4 low, vacuum lines good, and so is the rest of the stuff. Your video gave me a good lead, when I click on 2hi the button flashes but I dont hear any noise like I used to, I'm going to check the "computer brain" (I for get the name) and anything around it, thank you for the video. Maybe my nights of curling up in the shower and crying from the blazer problems will end.

[@MattyTxp]

I have an S10 that had a partially engaged 4x4 due to transfer case switch failure. It was making a grinding noise from the front axle gear disconnect being slightly engaged. I replaced the switch, but I'm not sure how chewed up that gear is or how expensive of a job it will be to get repaired.

[@brandoncuozzo6030]

Did is sound like a roaring noise coming from front passenger side? I got a issue similar to this. Got a roaring noise when in 2wheel but not in 4 wheel. An when 4 wheel is engaged the front tires are not pulling. Sounds to me like she is not engaging or disengaging all the way but not 100% sure.

[@MattyTxp]

@@brandoncuozzo6030 yes it was making the noise in 2wd and would go away once I pressed 4hi. What happened with my truck is that the transfer case switch was stuck open and not making a proper seal. This led to the vacuum actuator partially engaging the front right axle in 2wd. The transfer case switch was easy to replace. It's on top of the transfer case. Removed the lines going to it, removed the switch, put the new switch on, out the lines back on. It's a common issue, but not the only possibility.

[@mickestahl66]

Thank you Michael. Your video helped me fix the 4WD on my S10 ZR2. Michael Stahl Sweden.

[@coreyward5157]

Michael Stål what did you replace on your zr2 I have a 2000 Zr2 and I replaced the part under the battery tray and the 4wd isn’t working still

[@mickestahl66]

@@coreyward5157 I try to explain what i did . Sorry for bad english. I found out that the vacuum system was leaking. Easiest way to find out is to switch the right fan control inside car, between last and second last step on the control. You will hear a "sucking"sound and the fan will blow harder on front window if vacum is working, mine didnt. I checked vacum hoses, and i was lucky to find a broken hose under the hood on driverside. I replaced it and four wheel drive was working again.

[@coreyward5157]

Michael Stål ok thanks...... I’m gonna give my a try and hopefully get it working agains

[@dksta2346]

Maybe you could help me. I bought a used 2002 S-10 LS with 3 button fwd It has has some issues like mirror buttons not working and other lighting problems. This is what is happening now. When I bought it 2 years ago it would not shift our of 2HI. This week on the road it started dropping into low range while in 2Hi. Not it also will shift in to 4Hi but I don't like the chirp when it starts to move so I only run in 2Hi. Where to look for the solution.

[@mattmac30]

For the vacuum actuator style, the cable corrodes over time and the vacuum system not strong enough to pull it. Especially if you have a body lift then the cable can get more binded and needs replaced. I’m replacing my cable and removing vacuum actuator and making a manual pull system.

[@Sam-xt5gb]

Yo, I have a 2000 Blazer 4x4. When I press any of the buttons (it has Auto 4x4) they just flash forever and nothing happens. Any ideas what's up?

[@lifesagardenyadigit]

Try replacing the transfer case encoder motor its not very hard.

[@jamesmeissner7527]

My 2000 GMC Sonoma will not come out of 4 wheel pushed the button light flashed.pushed a few times then light stoped trying to shift still in 4 wheel

[@dustyhallee7635]

Hi i have the same s10 blazer and my 4×4 just stoppex working, is their a vacume line ?

[@rpgattack2789]

I really need someone to reply to this comment. I’ve replaced the vacuum switch on the transfer case. I’ve checked all the hoses. The actuator is fine. The only thing I know that’s for sure messed up are the buttons themselves but I can get those to work enough to press them. The actuator is always fully sucked and has the cable pulled at all times yet the front wheels aren’t engaged. And when I press the buttons, all I get is a clicking in the differential and a whole lot of nothing after that. What do I do?

[@Hollywood41642]

Witch one of the 3 vacuum lines off the switch goes to the actuator ? changed the switch, was bad the ball was stuck in. still have no vacuum to the actuator.. sometimes just enough vacuum to hold a small piece of paper.

[@NECARLOG]

I'm not sure as none of mine use the vacuum system I pull the cable connected to the actuator and lock it engaged with a set of vice grips or have that bravada shaft. I would start at the actuator and trace it back to the transfer case.

[@DustinWalker-m5n]

Everything works on mine except the front wheels locking in, no grinding sound but I had the lock cable installed so I think the gear is messed up

[@Justme-cn6eh]

Where did you get the cable locker?

[@CarsonNolt-wq7sx]

IHave a 93 S10 pickup. Need to replace the front differential shift cable.

[@timpuckett6773]

Excellent explanation. However, it would be very nice for you to show in your video where the parts that you are talking about are located. Also, links to the different new parts that you were talking about would be helpful as well. Thanks.

[@kevinjames9710]

Hi I have a 01 blazer , 4hi and 4lo dash lights keep blinking. However I think 4lo is engaging because I can hear the t case wine. But the lights keep blinking. Any ideas?😐😐 thanks

[@waddenwadden3272]

I have the exact same problem wonder if you found a solution

[@adamlint9473]

I have a 2002 Chevy S10ZR2 and I have lost 4×4 in reverse only. Any suggestions are appreciated!

[@cognac8297]

Did you figure it out 🧐

[@johnhill6829]

I did a complete engine transmission and differential swap and cannot find where the front diff position sensor (2 wire plug on diff) plugs into in the engine compartment

[@EricSmith-zp8bb]

My S10 has all for lights stay on after starting? Any idea why

[@kirkelliott3713]

What is the name of the company you mentioned at the end of the video. Something Designs...that have a bravada alternative?

[@NECARLOG]

www.outfitterdesign.com/bravada-shaft.html

[@spegree02]

Every time I get in my uncles '91 sierra I look at the never serviced fully functional 4wd lever with envy

[@my1after909]

Hi, Thanks for posting this. I've got a 2000 Jimmy, that sat on blocks all year, for major gas and brake system overhaul. 4WD worked fine before. This fall, I 1st errantly put it into 4WD Low, and it wouldn't engage. Hasn't since. Wonder if that screwed things up? I've seen a S10 video concerning a bad ground wire, but I can't find a similar ground on Jimmy. That sounds like a good place to start. Any advice or pointers, would be appreciated.

[@NECARLOG]

Would want to see if the transfer case is shifting or not. The push button switches are known for having bad solder connections so that is a possibility.

[@Jesse-dt1pf]

If you go with either the manual cable setup or the bravada shift do you lose 4lo? It seems like with both you would only be able to use 4hi

[@NECARLOG]

Gear changes between 4 low and 4 high are done in the transfer case and is not affected by the front differential. You will still have 4 hi and 4 low as well as 2wd with the 3 button transfer case. If you have the 4 button auto 4wd then I would recommend the cable.

[@Jesse-dt1pf]

@@NECARLOG ok so you engage the diff with the cable and still use the buttons to switch between 4hi and 4lo?

[@jasonpfeil1981]

So my transfer case is stuck in 4wd. Can I bypass the vacuum actuator with a push/pull cable to engage and disengage the 4wd safely?

[@brandoncuozzo6030]

I have a roaring noise on front passenger side in 2hi. In 4hi there is no noise but front tires not pulling. To me it sounds like it’s in the front differential. Like it’s not fully disengaged an obviously not engaging all the way either bc front tires are not pulling in 4x4

[@brandoncuozzo6030]

Any advice would be greatly appreciated. Also was wondering the best way to check for vacuum leaks. I have a 2002 s-10 crew cab with the 4.3l by the way

[@frankruether4284]

So if the switch on the transfer case is stuck and causing full vacuum all the time, the 4 wheel drive won’t work even when the transfer case is in 4 wheel drive?

[@NECARLOG]

If it is pulling full vacuum locking the front axle and the transfer case is in 4wd then you will have 4wd but this can eventually cause damage to the front axle.

[@clarksavage5611]

next i guess its the plastic motor on trans case or ?

[@timcat1004]

What about the AWD 2000 Safari. Mine feels like the 4 wheel drive is on when I make u-turns.

[@anunentitledmotivatedmille7731]

Difs always locked on thos.

[@daddyfixit631]

There is no reason to change these factory 4x4 systems. They can be fixed for little of nothing. Putting in a bravada and splicing wires is cool if you wanna buy stuff and do alot of work over fixing a simple button to switch to vacuum lines to actuator. My blazer has 200k with the factory system. Vacuum line have to be replaced at some point guys.

[@yamahondazuki95]

There seems to be three vacuum lines off of the vacuum switch at the transfer case. Does only one of these go to the actuator under the battery that engaged the front shaft? Mine will not go into 4 wheel. I can hear the relay or whatever it is making a sound when I press the button. But the light just blinks once or twice and will not stay illuminated, essentially not going into 4wd. It seems like a pretty simple system to fox correctly im just trying to get a grasp of it.

[@archwebb407]

My 1999 ZR2 the front diff won’t engage. New switch, actuator, actuator cable and all the vacuum lines I could get my hands on were replaced. Any ideas on how to troubleshoot why it won’t engage or what I should do to start eliminating things wrong. With transfer case in 4lo and 4hi the rear diff functions but not the front

[@daddyfixit631]

@@archwebb407 is the cable actuating the lever on the trans?

[@danielpavlak1143]

Put the posi lock kit in. Pull the cable, it locks up the front driveshaft, but no 4wd. ????? 2000 s10 blazer 3 button.

[@lewisfutschik8231]

High beam light stays on when dim lights what to check

[@Elphxdav]

So if i go manual cable accuator do i have to cap loose vacum lines?

[@NECARLOG]

Elphxdav yes I would recommend finding the vacuum line that goes from the engine to the transfer case and remove and cap the line to prevent vacuum leaks in the future.

[@junebug92x]

if i put my 4 hi button on my 95 blazer it blows a fuse and i loose guages ! any ideas ?

[@Blueknight1960]

You have a short somewhere.

[@RobSteez]

I Cant even begin to tell you how many times I've had these fail in the past 10 years with 2 of the s10/blazers I've owned. Electrical, vacuum and cable, the dumbest finicky technical setup ever

[@Burrrrrrrr25]

I tried to lock mine in last night and my transfer case locked itself in neural and it took me a solid 2 hours just to get it back in 2wd

[@NECARLOG]

That's not good. Never had that happen to me. Hopefully that doesn't happen every time.

[@hemi1430]

its vacumed from the diaphram.. not cable its a hose

[@talonchorney468]

I’ve got an ‘04 Blazer Zr2 with auto 4x4 and when I hit the buttons on the dash nothing happens. No lights, no sounds. I am lost

[@ryantent7513]

I see this comment is from 4 years ago.. do you still have the vehicle?

[@davidwright3589]

Really that is alot of work

[@scottinWV]

Instead of the Bravada swap, couldn't you unhook the cable from the diaphragm under the battery, pull the cable tight, and put a cable clamp on it to hold it in place?

[@NECARLOG]

Yes this is a temporary solution many people do which I have done with vise grips only when needing 4wd until last week when moving my blazer through some deep snow blower packed snow got stuck and broke the slide collar that locks the two shafts together so ultimately the bravada shaft is worth the upgrade.

[@stevebigler]

Dude... you have the grounded cable sitting AT the red pos post? Step away from the computer.....

[@JohnnyRayKing]

4x4 tries to engage when slowing down.

[@alreid8486]

My 4x4 eñgages it not all the way in 4x4

[@robertleftwich1122]

Too much information at one time. Needs chopped into four segments.

[@aguila413]

fuck nothing happen

[@nelsonmason1552]

Mine want light up at all the switch is new