Chevrolet S10 4x4 Not Working? (Diagnose and Fix)

This video overviews easy ways on how to troubleshoot 4x4 4wd issues with Chevrolet S10 or GMC Sonoma. This also works for the blazer and jimmy in similar year models (94-2005)
Contact me at [e-mail]

[@wburke8628]

There are 3 vacuum lines on the switch in the transfer case. 1 is vacuum source from the line at the drivers fender coming off the check valve T. 2nd one is going to the vacuum solenoid under the battery that locks the front end in. 3rd is a vent that runs to a Y. There is a vent on the top side of the transfer case to the y then goes up to the transmission dip stick and is zip tied there. Also the supply vacuum hose comes off the drivers side manifold over to the check valve T. The Check valve T feeds a line to the Heater controls and also plugs into the vacuum accumulator. The nipple for the accumulator is under the ABS pump on the fender well. Vacuum line sizes are 5/32” and 7/32”. Also 3- 2” pieces of 3/8” are needed. Check to make sure the cable under the battery on the vacuum solenoid is free by squeezing the solenoid. Also using a brake bleed pump pull a accumulator on the solenoid to check for its operation. The failed switch on the transfer case allows tranny fluid into the lines and solenoid swelling and rotting the rubber. If your getting tranny fluid into and out of the vent line the the output shaft seal is bad on the transmission allowing tranny fluid into the transfer case. This overfills the transfer case pushing it out the vent and into,all the vacuum lines and heater control. Eventually this will rot all the rubber. Hope this helps…..

[@msh4281]

Great info thanks!!

[@jondickson75]

Just wanna say one more time thank you. You saved me a lot of money and a headache gone. It was the diaphragm under the battery. Slight tear. And to the 25 people that disliked this, enjoy paying the local mechanic bill

[@ezrollin561]

New to 4x4, I have a S10 crew cab this video just increased my knowledge by 100%, I will post again when I fix the problem, thanks!

[@ezrollin561]

I checked the fuse , then the push button for activation, then removed the battery box so I could take a look. Started tracing the vacuum line and found it cracked and detached where it connects to the nipple on the driver side fender well. I replaced the 5/32 hose and it seems to have solved the problem. Now with a basic understanding of 4x4 I can fix my problems and save big bucks. This was by far the best video that I reviewed, Thanks !!!

[@jondickson75]

Thank you. I know nothing about the s10, but had to work on this very issue for a friends truck. Your video is well done. Keep up the good work.

[@tonyaelizabeththompson6404]

Man, you just helped me out like you'll never know!

[@davidreid6957]

Thank you, my 1997 is stuck in this January 20 2022 snow on level ground. Its a ZR2 like the one you got. REALY REALY appreciate your video

[@nedaCFilms]

ZR2 models were badass trucks. Another 10 years prices are going to get stupid on ZR2 models.

[@kevinc1851]

Kevin C I had a 1991 Jimmy that used this same vacuum actuator switch. I replace 3 in 5 years and it always failed in deep snow towing the snowmobiles, very frustrating. The dealer did two under warranty and we did the third one on my friends hoist and said we need to find why these are getting all gummed up and the ball was ceasing. We traced the hoses on the top of the switch and found one line was a breather vent that ended behind the grill, in front of the battery with a foam filter on the end so this was intended to allow clean air in the tube. A closer look we found whoever installed the battery tray at the factory had pinched the hose and put a big slice in the hose which allowed it to suck in dirt. we cut the hose before the slice and stuck the filter on the end. No problems for the remaining 15 years I owned the vehicle.

[@jessedean1216]

Very informative,I'm restoring a1994 S10 .I LOVE S10'S!

[@DustinT]

Thanks buddy! What stage are you working on?

[@grandinfinite5921]

Thank you. You've given me great leads...

[@edwardmedina6440]

Thank you i know this video will help me to fix my truck Thaks!!👍👍👍

[@TheMalakaHoss]

Great informational video,, now I have an idea what to look for ,, thanks for sharing!!

[@kevinc1851]

I just fixed my 4x4 not engaging. I got a clue when my HVAC would not switch from top to bottom vent, that's a vacuum leak. Sure enough opened the hood and could hear vacuum hiss. Main hose coming off the manifold under the throtle body was almost completely broken. I shortened the hose 1" and connected it. No hiss, HVAC and 4X4 all work.

[@gushamilton5188]

Great vid man. So glad we got guys doing vids on this shit.

[@DustinT]

Hey thanks man! Glad to help out

[@jems6840]

@@DustinT I have the same rotted line where you applied duct tape on... Do you know what size is that specific line if I have to replace it...... Edit: Never mind I fixed it.... I cut the rotted pipe line on both side... It was 7/32 cable.... used connector on both ends and fixed it under 10$

[@macrichardson6966]

I have a gmc 2002 sonoma ,I had to replace the actuator under the battery tray.

[@scotquigley513]

Having problem finding vacuum diagram for my '2000 ZR2. Got any links? Truck is new to me. Need diagram of hookups on driver's side. Got some loose lines I need to find connections to. Any help would be appreciated, thanx!

[@MichaelPauley-kl6lz]

Very helpful, thanks again.

[@seanlingerfelt2755]

To fix your fuse issue get a aftermarket wiring harness to plug in to your oem harness the aftermarket harness should have the same colorcode to your radio. You have a wire crossed and it is most likely the green wire crossed.

[@briandalton1406]

You are so right thanks man

[@patruddiman4228]

Is there a relay for the push buttons on the dash for the 4x4

[@benm2081]

Good video man you 🤘

[@Mike_The_Hog_A_Nator]

Get your actuator from O’Reillys or your reputable parts house that has a Lifetime Warranty. I’ve gone through 2 in the past 4 months. That actuator tears extremely easily. Especially down here S. of Houston where it’s hot as hell. My main vacuum line to the actuator was just falling off also. Use a tie rap to hold it securely to the actuator

[@DustinT]

This is good advice, I’ve replaced a ton of these as well!

[@waltersteffensthezr2man431]

Yes they do I warranty mine out from O'Reilly's six times I went and got one from the junkyard and it's been working perfectly for a year now

[@albertconklin9173]

Can the cable stick and cause the 4vwheel drive not too work?

[@RobertSiwik1968]

Good info for my sons 96

[@cushionface09]

Good info Thx

[@stevedinn6569]

Excellent

[@alanm9401]

did you get a fix for the dead battery issue. We had same issue with my sons S10. It was a unique power line for keeping the radio on after the car was off and before opening the door. It was a a high amperage fuse under the hood. The new radio we installed did not utilize that feature. Pulled the fuse and we no longer had dead batteries. If you need more info let me know.

[@DustinT]

Same issue with mine! For now I have removed the radio

[@thomasdurbin6616]

Check the drivers door pin switch. Mine does the same thing. Just open and close the passenger door and it will shut off if that switch is good

[@nedaCFilms]

Check your power wires on the stereo, hook power wire(s) to accessory, so it only pulls power when key is on.

[@victorparr4018]

Hey are available ? Got a question

[@louisgallaher5487]

i have a 01 chevy blazer and i hear my clicking but the front tires dont spin at all... what do i do???

[@charliebilicki6827]

Have a 96 blazer u can here it in gauge . Vac pulls the boot in ad still no 4x4 any ideas

[@snowman4839]

Did you ever figure out the issue of the 4x4 just blinking on for a second and then going back to 2 hi?

[@lesliebarnett-tx3jf]

Thank you. I know nothing about the s10,

[@drugtalk101]

How hard is taking that boot off under the battery tray?!

[@nevinjacobs8577]

is this the same for the blazer/s10 with 4buttons

[@DustinT]

Should be the same thing

[@billyrooksberry3040]

What is that switch called you have replaced underneath the truck

[@daminwidi]

Probably too late but its called a Transfer Case Switch

[@larrygolden167]

So it is not ice freezing the actuators. What happens is the input shaft seal in the transfercase is bad allowing trans fluid to transfer from the transmission to the transfercase. When the transfercase fills high enough transmission fluid get in your vacuum system via the vacuum switch which starts degrading the rubber in your actuators and vacuum lines. This will also cause problems with the hvac vent controls eventually.

[@benjamindales1911]

Currently, it is in 4 low /4 high but I cannot get it to ship the 2 Wheel Dr. I bought a new vacuum switch unscrewed the old one but now I cannot get the screw in. It is the wrong size or something. but that is not possible because it just came out of those threads. With it being in four-wheel-drive, that would mean the button would be pressed if it was screwed in and I can feel my finger in feel the part that pushes in the button, but I do not think it is put pressure on it. it still does not screw in. I’ve tried pressing the button while someone starts it and tries to shift it into 2 Wheel Dr. But it’s still will not shift into 2 Wheel Dr. any ideas?

[@galenhof3371]

I believe that switch is on top of the transfer case, not the transmission

[@xyzzz2138]

Just bought a 03 s10 and 4X4L works but high doesn’t any idea?

[@RaoulThomas007]

xyzz Z I would start by removing the upper plug on the transfer case. Does transmission fluid come pouring out? If so the seal between the transfer case and transmission is leaking. Replace the $20.00 seal and blow out all vacuum hoses with trans fluid in them. This is very common on second generation S-10’s, Blazers and GMC and Oldsmobile “clones.” Then I’d go to the actuator under the battery and battery tray and look for diaphragm tears, a rusted/frayed cable and disconnect the hose to the actuator and look for transmission fluid. Spray the cable with a good corrosion inhibiter, as long as you are there. Finally trace all vacuum lines and replace any and all leaking vacuum lines. If that fails, it might be your switch in the dash.

[@junebug92x]

if i push 4 hi on my 95 blazer it blows a fuse and i loose my guages. any ideas ?

[@RaoulThomas007]

John Belliel I would be tempted to replace the 4WD switch initially. It’s only $20.00 at NAPA and could be your problem. Obviously you are overloading the circuit that is blowing the fuse. However, where that overload is located is an entirely larger issue.

[@jonross377]

So my switch works just like yours I hear the noises like it locks in but still no 4x4. It acts like its locked in and the buttons say it is in 4 wheel drive but it isnt. when I press the 4low button my gear ratio does change but still no power to the front wheels. Could my problem be the boot under the battery?

[@bobtilson1952]

Yes fixed the actuator works like a champ

[@jeffeby6030]

The front differential on my 2003 GMC Sonoma is locked in 2wd. The shaft that is connected to the actuator cable can't be pulled out, even manually. All other parts have been replaced, actuator, actuator switch, vacuum lines. As said above, even with the cable disconnected the shaft cannot be manually engaged

[@TheGerkinater]

Is it electrical

[@iamSIGH]

👍🚗

[@puffthemagicdragon9534]

TCCM?

[@jorgeavila1264]

better illumination would do a great instructional video to WATCH.......

[@shizanepimp1]

I'm sure the rubber boot on mine ripped today, I'm sure of it. Right when I needed it to.

[@cameronmadden3825]

i got stuck when my s10 was supposed to be in 4wd and the front tires wouldnt pull, i kept spinning and fire started dripping from somewhere under the front. what could have caught fire?

[@kymiles8120]

Cameron Madden dripping fire?!

[@cameronmadden3825]

Ky Miles sadly yeah it had fire dripping from under it. idk what burned up i thought maybe it wasnt fully engaged and the gear burnt off but idk because it was dripping like plastic

[@kymiles8120]

Cameron Madden ohh did you look under it to see? Or did the whole thing burn up?

[@cameronmadden3825]

Ky Miles I looked under it to see because i seen a little smoke but i dont think anything metal could have got that hot to melt like that and drip just from the 4wd but im not sure

[@kymiles8120]

Cameron Madden no definitely not from the 4 wheel drive. Goodluck fighting it out though

[@wanderingone64]

easier said then done, the switch was easy to take off but it was a pain in the azz to put back

[@JodBronson]

LOL

[@waltersteffensthezr2man431]

So true !!!! I will say this if you have a body lift on your truck like I do then everything gets easier it's amazing.

[@HardCoreGarage]

Im goimg to pull my battery right now!

[@strangerdanger1271]

Pull your damn radio and wire it right. It is clear to me that the wire on the stereo is hooked to constant power instead of switched power.

[@POORLEO1]

the switch on the transmission that has the three lines-- what does each line go to -- as it is keyed - or does it even matter??

[@DustinT]

I would like to know this as well

[@RaoulThomas007]

One hose is: (1) Vent to Atmosphere; (2) Source of Vacuum; (3) Actuator. If you place the Index Pin at 12 o’clock and go clockwise then: Vacuum Supply/Source; Actuator; and, Vent to Outside. It doesn’t really matter, it only matters that the hoses have integrity and are not leaking (or have transmission fluid in them)! The cap ensures that the hoses are oriented correctly. At 6:28, that line/hose should plug into your vacuum reservoir (not ABS) which is hidden in the driver’s side fender. Sometimes that nipple is broken and the hose is disconnected.

[@craigsmith3160]

Goodsite

[@leviblanchard8256]

Did it idle rough too? Mine wont go into 4x4 AND it idles rough...

[@coolcat2997]

Same did you find a fix

[@jordannice6984]

My lights aren’t turning on like wen u press the button it turns orange mine isn’t? And it’s not going into 4x4

[@scotquigley513]

You got a problem like mine. Probably a vacuum leak somewhere. My lines were trashed! I'm in the process of replacing them.

[@waltersteffensthezr2man431]

Do not buy the doorman replacement actuator I had to warranty that dang thing out 6 times I went to the junk yard and got a factory gm one and it's been good for over a year doorman is the only manufacturer that makes a replacement actuator and they just don't make the diafram rubber as good as factory rubber please trust me on this. Go to the salvage yard!!!! ZR2s Rock!!!!!!

[@JodBronson]

+Walter Steffens - You are right! Nothing beats the originals! :)

[@TheGerkinater]

My 4x4 buttons are not turning on at all or engaging

[@jaramiepayne6341]

I can hear it engaging at transfer case but front end won’t lock in

[@jonross377]

Me too did you figure it out? Was it the actuator under the battery tray?

[@Sandberm]

On my 03 S-10 the 4WD wasn't working because the vacuum line that engages the actuator under the battery was rotted. The vacuum line runs from that transfer case switch that Justin showed us up over the top of the passenger side of the engine to under the battery where the actuator is. (BTW, do not buy the Dorman actuator if yours goes bad, they are cheap junk). I bought a new length of hose to replace it and ran it so it wasn't laying on top of the valve cover for that is where it rotted due to the heat. Any parts store has the hose in bulk. Just buy the length you want. A second line that comes off that transfer case switch is what makes the actuators under the dash that controls where the air is directed in the cab. So if when you turn the direction of where the fan blows(feet, face, etc) and it doesn't change, it is because either that hose is rotten or the transfer case switch has gone bad allowing transmission fluid into the lines. This can be a big problem as it could be damaging those actuators under the dash and they are a pain to change as you have to take the dash out to get to them. It could also damage, as it did mine, the temp, fan speed, direction of air flow switch in the dash. That's not so hard to replace. There is also a round vacuum collection ball in the drivers side fender that will get tranny fluid in it. Hope my experiences help someone.

[@darthjar9117]

The problem I’m having is I can’t get it to go back into 2HI

[@timothybriney9788]

I call that paint job "tweeker black"

[@martinneps9387]

Do you wanna sell this truck please coming back thank you for the Video I'll be waiting for your comment back if you why sell it or not

[@DustinT]

If you’re interested I would be glad to show it to you, email me at [e-mail] and we can discuss!

[@martinneps9387]

@@DustinT I do not do computers I'm doing KZbin on my cell phone

[@DustinT]

Sorry I’m just now reading this. Text me at 870-350-5836

[@AbandonedExplorationUrbex1979]

Every once in awhile I have issues with the 4 x 4 on my 2000 Jimmy.

[@DustinT]

Any idea what it is?

[@JodBronson]

+Jason's Journeys - It might be your Transmission Fluid Flooding. Why? There is a Rubber O Ring between your Transfer Case and Transmission.... When that goes bad.... It leaks into the Transfer Case... When the Transfer Case is full..... The Vacuum " SUCKED " that into the Vacuum Line. By doing that, the Line got Flooded and Vacuum Loss causes NOT to be working correctly! NOTE 1: TO FIX:.... Under the Hood.... Find the Vacuum Line that is in the " Middle " of the Engine, close to your Wiper.... That is the Line.... Take that off... Then take the Line that is " Under / Close " to your Transfer Case Off.... IF YOU SEE DRIPPINGS..... You have a Leak.... Go back to under the Hood... Take that Line and BLOW on it..... You should see bunch of Fluid coming out..... That means you are freeing the Vacuum Tube from Transmission Fluid. NOTE 2: REMEDY.... If you have Trans Fluid Leaks... Try a Bottle of Lucas Transmission Sealer..... This will help you for a while. :)))))))))))))

[@waynemathias1115]

Sonoma will start but won't engage in any gear

[@rexmuntz387]

My don’t work or click

[@esauce307]

Someone PLEASE help me!! My 99 Blazer has all of the 4x4 lights on and when I press a button it wont do a single thing... not too sure what the deal is someone please help!!

[@ginaboos9563]

u can pull fuse reset it or selenoid on transfer case