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Chevy Silverado and GMC Sierra 4x4 Questions



  • vehicle does not shift into 4wd in either auto 4 or 4h or 4lo. it does shift to low when 4 low button is pushed. switch panel lights appear the same as when system worked. occaisonaly when switched to 4wd it will blow atc 30 amp fuse and then no witch panel lights and service 4wd message of course. I removed front axle actuator and it appears to work fine.
    any advise appreciated
  • Try new select switch( The push Buttons ), also the connecter at the front accuator will sometimes have a short in it.
    Lots of luck
  • jason2500jason2500 Posts: 3
    edited September 2010
    I have a 2003 sierra 2500. I reently shifted the truck to 4 hi ti pull a trailer out of a ditch. i didnt have enough power to pull it out so i shifted to 4lo and pulled it out fine. I noticed whe i got back on the level ground i tried to shift back into 2hi and nothing would happen i ended up having to remove the motor from the transfer case and shift it manually to get home. once i got it back to my garage i reinstalled the motor and now the lights on the selector switch will only come on for a few seconds when i start the truck snd then nothing at all. I have tried a nnother incoder motor that didnt work and i swaped my switch out to my brothers truck and they worked fine in his.does any one know what the problem could be
  • jdsholtzjdsholtz Posts: 3
    edited October 2010
    while driving it seems like the trans downshifts and upshifts fast,like a stumble but the engine stays steady according to rpm gauge.could the speed sensor be a problem,and is it on the end of the transfer case? some one told me the tps could be the problem?
  • it doesnt always kickdown when floored,rpm goes up but trans doesnt kickdown. also noticed a bad vibration when doing kickdown test,sometimes works fine then dont at times.????????? stumped
  • I have a 2003 Chevy Silverado 2500HD, the service soon light I have had NEW wires and plugs, and new COIL PAK, I have also had dual put on. I am still experiencing a miss. Okay so I turned around and had the injector cleaned. STILL MISSING!!!! What else could be the problem?
  • have your o2 sensor checked, they need to be replace around 60,000 miles.
  • rihan5rihan5 Posts: 1
    Hi new to this forum.My question is I just bought a 2005 1500 sierra z-71 and when I put it 4hi an turn it makes some bad sounds. Going straight sounds ok.Took it back the dealer and he said it was a normal sound when you turn in 4 wheel(something about the clutches coming in and out.)drive.The mech. said he went and drove two trucks the same as mine on the lot and they both made the same noise. I have a 2000 chev blazer zr2 and it does not make that noise in 4 hi but they said it is a differant drive system.Does that sound about right or should I take it some other dealer.
  • bdwlf2bdwlf2 Posts: 1
    Having a problem with power to front axles in 4wd. I put on stands and put in 4wd and all wheel spin. If i hold brakes, the front dont spin. The front driveshaft doesn't spin at all either while there is a load on it. The front axle does engage though. In neutral with 4wd on, the front axle, driveshaft and everything move.

    Now it does go into 4wd low, but still having problems with the power going to front shaft. Again up on stands, all wheels spin great. But i hold brakes and only rear spin. Could this be an actuator problem on transfer case? Bad fluid? Vaccum line? Or is the case just bad?

    All 4wd selections including auto 4wd have same symptoms. But drive shaft does jerk like it wants to spin, just not enough power. 2WD works great, and no funny sounds, smells, or clanking in any selection.
  • The dealer is right, it is normal to hear/feel chirping/binding in the front end when in 4hi/lo while turning, especially on dry pavement. And your Blazer does have a different front drive system than a full size sierra. Plus the sierra has a lower gear ratio than your Blazer which also adds to the binding while turning. I have had several Z-71's and they all did it.
  • I have a 2000 GMC 2500HD with the 6.0 adn the 4l80E. I just replaced the transfercase encoder motor which engages the transfer case in and out of each option. 2h, 4h, neutral, 4low. before i replaced it i had a bad encoder, now that i completely installed a new one, which was easy to do, whenever i push the 2 HI buttom, it engages into 4 low. When i push the 4 HI button it goes into 4 low as well. I cant put the transfer case into Neutral at all by holding both 4HI and 2HI buttons, and when i push the 4 low button i get 4 HI???? whats going on with my transfer case. Anything helps.

    Thanks! :sick:
  • I have been having problems with my 4X4. I have the push buttons. It works sometimes but others it wont. I recently checked both of the motors in the differential and the one to lock in the front wheels. THe drive shaft going to the front wheels locks and i jacked up the front end and the front wheels spin opposite directions meaning its all engaging. I took it out on a county road and it would not spin the front 2 tires in a burnout in 4wd Hi or low. Any suggestions? THanks!
  • Check to see if your drive shaft is turning while the front wheels are turning, then check your switch, also if you have had any of the wires going to any of the 4X4 parts unplugged without taking the battery cables off, you will have to carry it to some one who has the electronics to clear all that has been done.
    Mine did the same , so I was a fix it my self, when I did see I could not fix it ,I got person with electronics to check it out, there was 25 codes on it and a bad selector switch.
  • I have a 95 Silverado 1500 4X4, the dash gauge shows it's overheating (avg close to 260 range) within just a few minutes of operation.

    New thermostat, radiator & temp sending unit but still shows overheating.

    We installed a manual gauge, this one shows the temp is within operating range & that thermostat is opening & closing appropriately.

    Any suggestions on what to check on the dash gauge? The ground wire is attached correctly but maybe we're missing something else.

    Thanks in advance for any assistance!
  • Yes , try replacing you dash gauge
  • Its been intermittently failing the key-start self-test, no LEDs lit behind the buttons, no action when buttons are pushed, puts the "SERVICE 4WD" onto the DIC, happens more frequently in wet weather, and sometimes happens while driving, although, it has never made an un-commanded shift into 4HI or 4LO. Its been doing it for off and on for a few weeks.

    I researched thousands of postings on the Web about this problem, and I have fixed it (for now). In the process, I drew out a wiring diagram of the Transfer Case Shift/Servo Motor, a Pinout, resistance checks with an Ohmmeter that can be done without removing the Transfer Case Shift/Servo Motor and that information is posted here.

    Hope this will help you diagnose this common problem.
  • I recently got a used '08 4WD Chevy Silverado..I upgraded from a '06 2WD Silverado. Well I finally got to use the 4wd but theres this problem while shifting back and forth from 2wd to 4wdHi the floor shifter seems to stick..It seems like ai really got to struggle to shift from 2wd to 4wd..I thoguht it would go smoothly.Am i doing something wrong? Also I seem to have the problem everyone else is haveing when they turn. I hear a grinding noise and my truck shakes when turning, I thought I had snow stuck under my truck what is the problem. It makes no noise in 2wd...can someone help me out here?? thanks
  • gmcustsvcgmcustsvc Posts: 4,251
    I would recommend taking the vehicle to your local authorized GM dealer of choice. If you need assistance locating a dealer, please let me know.
    GM Customer Service
  • I read this post and didn't see my issue so I hope someone can help. I have a 1997 K3500 that has 4lo but not 4hi. Replaced the front axle actuator and the ball switch on the transfer case is working. Can anyone tell me what to check?
  • My guess the encoder motor.

    I have a 1999 140k miles have replaced the encoder motor once & and the front actuator 2 times, the dash switch 2 times, rebuilt the transfer case once.

    link shows encoder motors motor&_sacat=&rvr_id=193394075195&MT_ID=335&crlp=1263599956_9887&tt_encode=raw&g- eo_id=491&keyword=encoder+motor&adgroup_id=773792716
  • I have a 2001 Chevy Silverado and recently the service FWD service light turned on. It all started when I was driving the lights and radio started to flicker on and off as if a battery cable was loose. I went home turned off the truck checked the battery and it was fine and when I turned the truck back on the FWD service light was on. I replaced the transfer case select switch and I am not pulling any codes from my code reader, I am thinking a loose wire? Any suggestions?
  • What does the encoder motor do? And thanks for the help!
  • The encoder motor is an electric motor which is used to shift the transfer case from high to low range. Also included in the encoder motor assembly is a position sensor which sends the actual position of the transfer case shift shaft to the Transfer Case Control Module.
  • "The Electric Actuator/Motor Is Used To Engage Transfer Case In And Out Of Four Wheel Drive On Chevy Truck Equipped With Electronic Shift 4x4. "

    I have a floor shifter and this makes it sound like its only on push button shift models?
  • Can someone tell me where to find a wiring schematic of the 4x4 system on a 1997 K series with a floor transfer case shifter?
  • About a half pint of Autotrac II transfer case fluid was added to the automatic transmission of my 99 Sivlerado. Is this going to cause problems? Should I change the fluid as soon as practical? It has been in there for about a week already; I cannot feel any problems as of yet.
  • I have a 2004 GMC Sierra with the dreaded "Service 4-wheel drive" message in my display. It happened a few weeks ago and is on-going, although intermittent. One time after turning off the truck (went into a store for some parts) and came back out, it was in 4-wheel low. I shut it off and restarted it and it was back in 2-wheel hi.

    I took it to the dealer and they said I needed to replace the encoder motor. I bought it from them and replaced it. Easy to do, I might add.

    3 or 4 days later, the same message reappeared. I went back to dealer and they said it could be the switches instead. I bought the switche and replaced them (in about 5 min).

    Few more days, message is back. I called the dealer and now they want $90 more to "reset" the code. They say it's not really broke, but I just need to pay them to reset the code and all will be fine.

    My question is, if the parts have been replaced, do I really need to have the code reset or should it reset on it's own. I hate to pay them more money if it doesn't fix the problem.

    I'm in for $90 for reading the code the first time, $400 for the encoder, $90 for another read, $100 for the switch. that's almost $700 and the truck is still doing the exact same thing.

    Any other options for what this cause is. I checked the battery ground and it isn't corroded at all.

    Your help is greatly appreciated...

  • 2006 4x4 auto z-71 5.3L truck is going into neutral while still in gear. When I push the all-wheel drive button all gears work again I than push 2-WD button and it works for a while as norm. but than will kick back to N again. Makes a loud clunk if I don't stop to put in all wheel. Now it wont ingage in 4 -L ??? any help??? there is some Metalic in the transfer case oil..
  • has anyone found an answer to this problem..I also wanna convert my 02 over to manual 4wd.
  • Have you yet to find a solution to the problem? If so please fill me in. I just had the same issue with my 02 Silverado. The lights just went out on the 4x4 indicator and I am getting no 4x4 function. I changed the switch and it still wasn't working. Next is the transfer case actuator from what I am told, if that is bad you will lose power to the 4WD. Let me know if this was your solution too. Wouldn't mind saving the $79 if it's the wrong direction.
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