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Chevy Silverado and GMC Sierra 4x4 Questions



  • I have a 2003 Chevy 1500 and have been getting a service 4wd warning message. I have changed the oil in both axles and the transfer box. Does anyone know what the heck I am supposed to 'Service' now???
  • I have had the same light flash on my pickup as well. I have a 2002 Chevy Z71. I would only see if flash once when I started my pickup but it would not come on and stay on like the other warning lights for changing engine oil or low washer fluid.
    I was like you and I changed the front and rear differential fluids along with the xfer case. I believe that the manual says something possibly with the xfer case and that my have to do with the fact that the Z71s have the automatic xfer case or the auto 4wd button. The last time it came on I changed the front differential fluid and hasn't come on since.
  • rockyleerockylee Posts: 14,011
    Is there a sensor in the system ?

    That is interesting. :surprise:

  • I have a 2000 z71 and that message always comes on did you ever find out why or what it is?
  • sly4isly4i Posts: 1
    I have a 2000 Chevy Silverado 2500, my sevice 4wd light was on. I had taken it to a local transmission repair shop and I was informed that my transfer case connectors were corroded and was not getting a good connection, so whenever it would rain or snow my service light was on. After repairing this and $450.00 later. The service light still persisted to come on. So I went to a GM dealer and bought a new switch, this finally fixed the problem. hope this helps everyone. Major suggestion given "check the switch first it is only $65-$70 brand new.
  • Thanks for the heads up!!...I will try the switch first. I also spoke with a couple of buddies who work for GM electrical and they suggested replacing the switch also. Interesting about the connectors on the transfer box...I think I will clean them up just in case and spray them with a protective coating, if nothing more might save me $450 later on.
  • You need to try and change your transfer case control switch.
  • kegabearkegabear Posts: 5
    i have a 1996 silverado,bought from a friend .he never had a problem at all.ive had it 18 months and put 30,000 on it with no problems...has 110,00 on it now...90,000 of it is all hwy miles
    on the way to work a couple days ago at 75 mph the 4wd just kicked in by itself..couple loud bangs seconds later came from the front wheel area.
    anyone ever have this happen?
    was stuck in 4wd for 10 minutes or so till i finally got it out into 2wd then pulled the fuse for the tranfer case so i could make it to work.
    just had 2 front tires put on..slightly different from the rear..heard this could be the problem as you need to match them perfectly.
    asked 5 diff friends and got 5 diff answers.
    also isnt there some kind of failsafe so this wont happen if it happens to be a short in the switch?
    drove it home with the fuse pulled (about 50 miles) with no noises..seems to be ok but im afraid to put the fuse back in till i find the exact problem.
    has an automatic tranny.
  • 1offroader1offroader Posts: 208
    I'd look at the dash switch, the transfer case solenoid that controls the 4WD, and the solenoid that controls the engagement of the front differential. I think there's less chance of a problem with the tires. Factory spare tires are often smaller than the others - if that was the problem you'd hear a lot more about problems like you're having.

    Did it shift into 4Hi or 4Lo? If it was 4Lo, then the problem is not in the front diff. - the diff. doesn't have two speeds.

    Once you figure it out and do the repair, make sure you take it offroad and put it through the paces to make sure there was no damage. You don't want to find out when you really need 4x4 and it's not available.

  • kegabearkegabear Posts: 5
    it kicked into 4 hi..i have unplugged the solenoid and will take it out for a test once i have replaced the parts...tough to tell which one malfunctioned so i guess to be safe i'll replace them all..i know its all in sync but dam..should be some kinda failsafe speed so it doesnt kick in above like 50-60 mph
    thanks for your help!
  • I have an 03 Silverado Z71 ext. cab. and just recently the 4wd system has been acting up...

    I have the AutoTrac system and when I go to turn the truck on, sometimes it says it is in 4wd, auto or neutral. It then tells me to service 4wd, no other lights are on and I'm not turning on anything...

    Most the time it is normal and in 2wd when I turn it on.

    Mechanically the sytem works like normal when I want to go 4wd I just push the button as normal and it works...
  • Mine is 2004, but does the same thing. Have had it fixed twice under warranty (now out of warranty)and happening again. There is a Tech service bulletin on this, your mechanic friend should be able to pull it up on his computer
  • I noticed today that my transmission was in 4H as I was driving down the freeway. Not sure how it got there and not sure how many miles I drove it this way. Is this an issue with this knob? Further, have I damaged the vehicle?
  • geno57geno57 Posts: 1
    i have a 2000 gmc 1500 4x4 it makes a whining noise at any speed it gets louder at highway speeds and the truck has 214,000 miles
  • geno57

    You've probably got a bad bearing somewhere but without more info. it is impossible to diagnose. Could be wheel bearing, transmission, transfer case, rear diff. Does it vary with vehicle speed or engine speed? Example: If it's a power steering pump it will make the noise under the hood even though the vehicle isn't moving. Rev the engine with the hood up and listen. If there is no noise it is somewhere in the drive train. You could put all 4 corners up on jack stands, have someone put the truck in Drive, and listen to each wheel bearing as the wheels turn, and crawl around underneath and see where the noise is coming from - transmission, transfer case, etc. Be careful with that, make sure the truck is secure before doing anything like that, and don't get any loose clothing near any spinning items in the drive train. Even if you find the location of the noise it might not be something you can repair yourself unless you are very sophisticated, in which case you probably already know what I've just told you. Good luck.

  • grampy1grampy1 Posts: 140
    2004 Sierra auto. manual 4x4 shift on the hump.
    I have been told,and the manual says that i can "shift on the fly" from 2 wd to 4wheel high at any speed below something like 45 miles per hour,and back. When i try to shift from 2 wheel to 4 wheel at say 25 mph ,its like shifting a standard tranny without the clutch.
    I guess i'm expecting that the S.O.F. to be smooth. Truck has done this since new, especially when cold. Manual says you can shift while truck is in motion.
    Thoughts from 4x4'rs appreciated.
  • djm10djm10 Posts: 1
    I have a 2004 2500 crew cab duramax 4x4, my father in law has the same truck and my brother in law has a 2001 2500 crew cab 4x4 with the 8.1l in it and we all have had problems with front wheel hub assemblies going out. both me and my father in law have replaced both sides twice in 46K miles on our trucks and the othe truck one set. All the trucke have 4" Rancho lifts and 305-70-16 tires of different brands.The bearing are National brand that we've been using(National beening a repitable company). Has any body had the same problems or can you refer me to another site to discuss this, Thanks.
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