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GMC Jimmy 4WD Problems



  • I had the exact same problem with the whining noise on my 95 blazer. Problem resolved by replacing the vacuum switch on top of the transfer case. It leaks down the vacuum, which causes the front axle to partially engage and moan/whine. The vacuum switch is a very inexpensive repair.
  • merandsmerands Posts: 1
    I am experiencing the exact problem with my 95 blazer. Can you please tell me how to replace the vacuum switch. I was unsuccessful in locating instructions on for this repair. Your help is greatly appreciated.
  • howie59howie59 Posts: 11
    I have a 2001 4x4 GMC Jimmy with auto 4 button switch that is stuck in auto mode and the ABS -brake is always on
    Things I have tried
    disconnected battery for 30 minutes
    repaired one disconted vacuum line near the intake manifold
    replaced both front wheel bearings/hubs

    I have read most posts about this and dont know what to do next
  • Auto 4x4 light,2H,4H and 4L lights flash in the dash often. Seems like engine will stall for a quick second then the service 4x4 light flashes on and sometimes stays on. Also noticed clicking sound from right hand lower kick panel when the 4x4 lights flash. 4x4 will engage when buttons are pushed. Have already replaced right front ABS sensor, tried other encoder motor and problems still occur-PLEASE HELP! :confuse:
  • Everything works like it should,but where the cable pulls
    on the front axle to lock it in nothing happens.I tried
    to manually put it in but it still doesn't work.Was wondering what couldbe wrong inside the front differential
  • OK today i feel really stupid after months of wondering what the heck happened and why the 4 wheel drive stoped working i decided to go down the line and check the fuses well apparently fuse 19 was bad which works the 4wd switch box i guess i changed the fuse and i now see the lights light up and i can feel it kick on when i put it in 4LO
    But amm wondering i had some help from a friends we lifted all 4 wheel up using 1 jack in the front and 2 jacks in the back
    got all 4 wheels of the ground i wanted to just see if the 4 wheel drive works still and i dont understand how come the front wheels dont spin is it something that is just because it has to be on the ground will the Front wheels not spin or engage if the jimmy is not on the ground or is something still wrong check the vacuum lines everything seems to be fine cant think of what the problem could be please help thank you
  • cacyrccacyrc Posts: 1
    We got a part (4wd switch) from an auto salvage yard because we thought it would fix the issue of the buttons being stuck. When we connect the part you can push the 4wd buttons in but now they do not light up as they used to. We are guessing that we just got another bad part. We also checked the fuses and they are fine. Does this sound like the problem to you too?

  • Are you trying to change from 4WD to 2WD when you are driving?

    I think its safer, if you pull over, put it in neutral, and change over to 2WD or 4WD.

    Mine jimmy's at about 150miles, 250kms, and my truck shifts from 2wd to 4wd to 4wd low perfect, I just keep replacing the trasfercase fluid every summer...its easy and so cheap to do.
  • I have a 1995 GMC Jimmy w/145k

    When you engage 4WD High, while rolling in 2WD Drive, it has a brief delay and you can "Feel" and hear it engage, but when you go back to 2WD, while rolling in 4WD Drive, it seems to wind out like it's in a Low Gear and seem to hear/feel mechanical "Grinding" then almost a loud bang and it goes back into 2WD and drives normally.

    I would almost think whatever engages or disengages the different modes is not doing so completely.

    Any ideas?

    Thanks everyone
  • I have a 2001 GMC Jimmy SLS with 130,000 km. It will not shift into 4Hi, Auto4wd or 4Lo. The TCCM has been checked and it is OK, and the shifter motor is OK and the transfer case shifts... BUT... when I push any of the buttons, the lights just flash and flash for a couple of minutes, and you can feel like it is attempting to shift, but it never happens and eventually the vehicle goes back to 2Hi. I don't know what else could be the problem if it is not the transfer case, shifter motor, or TCCM.

    Any suggestions would be greatly appreciated! Thanks in advance.
  • I have a 2000 jimmy with the automatic button. The check 4x4 light came on for a min. or so and went out. The wife was coming home and put it in 4 auto and was fine, when she got to a really bad roar she tried to put it into 4x4 hi but it went into 4 lo. Then it would not come out. when she got home and told me I went to check it out and it went right into 4x4 hi, then I pushed 4x4 auto and it went ito that. I pushed 4x4 hi again and it went ito lo and will not come out. What is up with this . I guess I need some help bad. thanks
  • hi this is brian i also have a 2000 jimmy 4x4 im also haveing the same type of prob i was told to check the vacuum actuator its under the battery try its got a vacuum hose and a cabel leaver check that and see if it holds when u push it in hold ur finger over the vacuum hole and it should stay in if not thats ur prob also follow the vacuum line up the the fire wall and ull see a peace with to hoses on it with a wire that gose to ur 4wd lights in side hope i helped u. im haveing the same problem mine wont lock in to 4wd and my lights aren't comeing on at all hope i helped good luck
  • i have a 2000 gmc jimmy i'm having problems trying to get the 2wd back i changed the tccm computer on the kick panel did that because the lights in side didn't work because i went in water with my truck now the lights are back on but its saying its in 4wd lo and will not come back out i hit the buttons the just flash and go's back to 4wd lo can hear it trying to go in to 2wd but nothing happen check all vacuum and vacuum actuator under the battery tray all good followed vacuum line from actuator up to fire wall all looks good not sure if thats the problem the hoses going to the fire wall looks good don't no if its working right any one have any clue what may be wrong :mad:
  • i have the 3 button style with 2 hi, 4 hi, and 4low. I've read all the postings in this section so i have already checked the vacuum lines and there ok , the actuator under the battery tray is working, i can hear the transfer case motor changing when i select 4 hi so i assume that is working also. but only the rear wheels are spining in the snow. any suggestions ???
  • i finally got mine working, I found out it was the puttons in the dash, I replaced them and now it works. :)
  • My 4x4 lights keep flashing and not allowing me to press any of them.
    I've disconnected the battery but still nothing.

    Also, the head gasket just went and we replaced it, but now the truck is running rough, like there is a vacuum loose. Any suggestions.

  • hey this is brian when u did the head gasket did u check to make sure the timeings on look and make sure its TOD to dead senter the timeing markes on the crank also check the TCCM on the pass side kick panel if u have any more Qess let me now ill try to help u out the best i can brian
  • hi this is brian did u check the plug on the diff to make sure the ball moves in and out like it should check that bc i had to check mine not sure if urs has it but dont hurt to look its next to the cable for the actuator its a plug and goes in to the diff look at that hope i may have helped if u may now y my jimmy wont go out of 4wd lo hit me up thanks brian
  • prm1prm1 Posts: 4
    My 1999 GMC SLT 4wd crapped out on me tonight. A few good klunks and then I can barely move. Sounds like a gear is grinding, like it can't quite engage. If I am stopped with the brake on and put it in either drive or reverse, something starts turning and making the same grinding sound. My best guess is that it was coming from the rear, but it was also raining hard so I haven't had a chance to listen to it from outside.

    It has been making some occasional klunking noises the last few weeks. It has also developed an annoyingly loud whine that goes along with wheel speed, and isn't affected by turning, braking, accelerating or shifting. The whine may be a secondary problem caused by wheel bearings, UJs or the like.

    Any ideas? Transmission? Rear differential? Something else? I've got to tow it, so what kind of shop should I take it to? I'd take it home if it was something that could be rebuilt in place, but I don't feel like dropping a tranny. Any suggestions? I have been wholly unimpressed with the dealer in terms of both price and service (I am in San Diego).
  • Hi there, seems we all have similar problems with these GMC's ........ hoping someone can add some advice for me.
    1998 GMC Jimmy, 4WD, 3.8 V-6, Automatic Trans .......
    2 problems ....... replaced my transmission back in January .... it had been "banging" going into 2nd gear after driving a bit and everything was heated up, then began slipping and eventually went completely.Got a junk yard unit and installed and all was good for about 10 months ....... recently this transmission has begun doing the SAME thing ..... 15 minutes of highway driving usually and the first stop you come to ...... shifts VERY hard and bangs into second. Check engine light comes and goes. Someone told me there is a valve that sticks for the lock up torque converter and it needs to be replaced. Anyone have any experience with this problem?

    2nd ........ my 4WD operates however ....... there is ALWAYS vacuum applied to the vacuum cable actuator located under the battery. I removed the vacuum line for now so i can drive in 2WD and if I need 4WD I have to re-apply the vacuum hose.
    Does anyone think perhaps the 3 port vacuum switch located on the top of the transfer case could be stuck or damaged allowing vacuum there all the time? I have removed the connector and made sure it is on the right position. It is keyed so it would be difficult at best to put it on wrong. If this is a good possibility ....... is it difficult to replace by yourself or does this have to go to a shop? I saw the switch on line for between 25 and 35 dollars.

    Thanks all for any input I can get and good luck to you all!
  • Following up, it is definitely in the rear. It seems most likely to be coming from inside the transfer case. I tried putting it in 4lo and it would move, but would make a horrible klunk after 4 or 5 feet, and I could visibly see the rear axle (I was on the right side) move awkwardly when it klunked. That was my last test, and then I had it towed home.

    Does anyone know if that is something I could reasonably look at myself without a bunch of specialty tools? I have rebuilt several engines, replaced cv joints, rotors, and wheel bearings, but I have never cracked a transmission or a transfer case. Would you normally rebuild it in place, or replace the whole thing? Has anybody had to deal with this problem, to give an idea of the cost to repair?

  • check and see if you have the vac switch in the middle if the fire wall, my hose was broken there and lights were flashing.
  • Ok it was the intake gasket my husband replaced, not the head gasket..and then he found out why it was running rough...he accidently bent a couple of the "fuel injector jets"...fixed and now is well.

    As for the flashing lights for the 4 wheel..i'll have him check the vac switch as woodsman3 suggested. Thanks for the advice!

  • ok i have a 1992 jimmy and i cant get the 4x4 working and i was woundering if there is a way do engage it maunley
  • 3 button 4wd would not switch into 4hi or lo until the other day it went into 4hi and now it won't disengage... similar problem as others, lights on dash will just blink... spent hours reading forums trying to make sense of it all cuz i can usually teach myself how to fix things... so here is my progress and q's

    replaced TC switch on TC motor, the old switch was definitely shot and there is vacuum to the actuator under the battery tray, when the hose is disconnected the cable moves, afterwards disconnected the battery in an attempt to reboot the TCCM to no avail

    1. since the dash lights are responding correctly as to whether or not 4wd is engaged/disengaged does that mean the sensor on the front diff is working properly?
    2. because i have vacuum to the actuator then the lines should be good, right?
    3. where and what are any other sensors or switches i need to check?
    4. how do i tell if the encoder motor or the TCCM (i hear clicking when button on dash is pushed) is bad?

    any help is appreciated
  • dave, seems we have the same issue... just replaced the 3 port vacuum switch... to say it nicely it was a major pain... all it took was a 7/8 wrench but it was hard to see and to get to... its only $15 at autozone... maybe it'll work for you
  • ok so when i push the 4x4 button (two way button) nothing happens i can hear something clicking it sounds like its coming from the glove box area but it wont i put a junkyard actuator in it and it worked kinda the light showed 4wd but i dont think i was in it, the right side back tire would just spin so i played with the button repedly pushed it and know im back where i started and any one help me it starting to get frustrating.
  • I have similar issue my oo jimmy goes into auto 4 wheel when first started up, but as soon as u go around block service 4wd light comes on and auto stops working sometimes, local mechanic put on comp. and said rear actuator was bad which I think that is encoder motor but I thought encoder was only for 4 low engagement does this sound like axle switch or under battery actuator, or what, someone can help me? thanks chrome_eagle
  • I have similar issue my oo jimmy goes into auto 4 wheel when first started up, but as soon as u go around block service 4wd light comes on and auto stops working sometimes, local mechanic put on comp. and said rear actuator was bad which I think that is encoder motor but I thought encoder was only for 4 low engagement does this sound like axle switch or under battery actuator, or what, someone can help me? thanks chrome_eagle
  • I have similar issue my oo jimmy goes into auto 4 wheel when first started up, but as soon as u go around block service 4wd light comes on and auto stops working sometimes, local mechanic put on comp. and said rear actuator was bad which I think that is encoder motor but I thought encoder was only for 4 low engagement does this sound like axle switch or under battery actuator, or what, someone can help me? thanks chrome_eagle
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