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Chevy Silverado and GMC Sierra 4x4 Questions



  • on my 2001 silverado the light is on 2hi and when i press 4hi or 4lo it flashes and goes back to 2hi
  • I have the 4WD shift on the floor, no problem shifting into 4W lo, but when I shift back to 2WD it is slow in responding, even when I slow down or even stop, it may not shift until later. Is that normal or what could be wrong.

  • just to let you know I blew the gears apart on the transfer case
  • I have a 1998 GMC Sierra, with the 4WD on the floor. When I shift into 4WD no problem, when I shift out, it is very slow shifting back to 2WD, even if I slow way down or even stop, it may take longer to shift out of 4WD. Is this normal or do I have a problem I need to address.

  • could be the encoder that is attached to the shift motor on the tranfer case.
  • hi I have a 2009 sierra reg cab 4x4 long box with the 4.8 and manual shift transfer case. i have owned the truck for about 2 months. When it starts to be pretty cold outside i get a clunking noise (sounds like somthing is rocking) when u turn or the truck starts to rock( coming in a drive way or incline on an angle). This noise seems like it is coming from under my feet, but then again the truck is steel so the noise could be transfered from anywhere. The noise happens not all the time and it does not always have to be COLD outside for it to do it. i have checked the spare tire,exhaust, front suspension,rear supension, looked for loose bolts. and have come up empty handed does anyone have any ideas? Thanks for the help ( and oh ya the dealer say's they have never had any complaints like this one before....... ya right)
  • dans04z71, I have a 1999 Silverado 1500 that does the exact same thing in 4X4. I'm very curious to find out if it was your front diff that was the problem??
  • an update i took the truck back to the dealer, and was told that the noise im feeling and hearing is coming from the reear axle, they told me it was axle play and nothing i should concern myself with...., guess im feeling it being transfered through out the truck........ im not sure if i should belive them because i had an 03 s-10 comp edition, and that truck never made this noise, and come to think of it i dont think ive ever hear that noise or felt it in any of the other truck i have ever ridden in......... on a side note i found my old truck at a dealer and when i started to ask questions about it the guy told me it had 116000 km on it,, and when i told him i was the original owner of the truck he walked away from me...... now i sold that truck 3 years ago to the dealer with over 100000 on it, sounds like to me that someone had turned the odemiter back!... and it was most likley the dealer considering he walked away from me when he found out it was mine.......... hum..........
  • having this same growling on my '06 sierra, are u referring to the shaft from xfer case or one of the halfshafts?? Never take mine off road, only 39K miles, only used the 4x4 a few times on ice, only does this in 4x4 when turning, sounds like the differential or something revving up, quiet after the wheels are straight, shift back to 2h NO noise at all. any help is appreciated
  • No that was not the problem. I'm still told by my machanic that its the clutches in the transfer case. Had the whole front end redone so i know for a fact that its not the front diff. I asked my uncle with the same model year as yours and he's got the same problem.
  • Hi I have a '99 sierra 1500 that first would stick in 4 hi. Dash push button shift lites would work intermetily. Changed the fornt axle accutator and she worked up and down our drive, test drive, for 4 trips then the next morning I started it and no lites and stuck in 4 hi again. The indicator buttons would lite when I turned the ingintation on. Took to a friend and he got a code co 327 but it would not give him what was bad. He used his DT'er to tri it into 2 wh. The lites went back off and he could not over ride that module up under dash. He believes that is bad, But like me not certain. Any idea's? Thanks
  • The rear shaft is live all the time on these vehicles. All of the gears in the xfer case are live alo. The power is transfered to the front wheels when the actuator is engaged. However, the shaft and case are turning live at all times the vehicle is moving.
  • Shift motor won't shift from hi to lo or back/ neutral to either,also blows fuse,but I can put a jumper in the fuse slot and it works.any thoughts?
    Can there be a short somewhere?
  • jknowlesjknowles Posts: 2
    i am having the same issues. I have totally torn my system apart on my 02 silveraado. I changed my t case encoder moter assembly and totally tore the front end down. nothing works under load but works when operating by hand. I put a bolt (dont laugh) into the end of my front diff actuator and now it works but not enough to spin the tires. I'm stumped too. any other ideas would be nice.
  • transfer case clutch plates shot? how many miles on the truck?
  • jknowlesjknowles Posts: 2
    only 130,000 kms and was working fine i think it all has to do with my front diff actuator
  • alan1818alan1818 Posts: 4
    Hi, newbie here, and I've just spent a while looking over old posts; there's a lot of great info in this forum!

    My situation: a '96 Sierra 5.7l automatic with push button shift, 106k miles, well cared for, but I've only owned this for 14k miles, so am not very familiar with it. Just recently noticed when I shift to 4H or 4L, the light just blinks, and doesn't engage the front wheels. Shifting to 4L does transfer to low range, however. From previous posts, this points to a switch, fuse, connectors or an actuator problem. Because the switch works to 2H (solid light) and to the low range (4L), and the wiring appears ok, I'm thinking front differential actuator or fuse. Can someone tell me where that fuse is, and/or if I should go directly to a new actuator?

    I followed the link from Bruce48532 to the parts supply, but the replacement actuator listed doesn't show it's for a 1996. Will the one listed still work? I presume the existing is an older thermal unit, and is the listed one a direct replacement?

    Thanks a lot for any replies,
  • messerbnmesserbn Posts: 1
    I have the same problem with my 04 chevy what did you get figured out?
  • ognendognend Posts: 1

    I recently purchased a 2500 HD Duramax Diesel with Allison transmission - it also came with 4x4 and has around 60K miles. The only reason I got this truck was to haul my horses. However, the darn thing did not come with an owner's manual. I was playing with the 4x4 switch the other day and I have 4Hi and 4Lo and 2H. I normally drive in 2H and I can also switch the truck to 4Hi. When I try to switch to 4Lo, the light just blinks but it eventually comes back to 2H. Having no previous experience with 4x4 vehicles, this does not sound right to me. Can anyone explain what the 4Hi/Lo are supposed to mean and what is the expected effect of pressing these buttons? (sorry for the dumb questions)

    In addition, when I switch to 4Hi, and do sharp, slow turns in gravel, the tires move very slowly and feel as if they are "skipping" in the turn (for lack of better explanation). Should 4x4 feel any different than 2wd on regular gravel (for example)?

    Thanks for any help!
  • alan1818alan1818 Posts: 4
    Well, I got a replacement front differential actuator, and it appears to have solved the problem. The front wheels now engage. I had to splice in the old harness, as the replacement had a different configuration, but otherwise a simple and quick fix.
  • I have a 2007 Silverado and recently i attempted to put it in reverse and after moving about 50 ft is stopping, like it was in neutral. The service 4 wheel drive indicator light came on. Switch was on Auto. I tried moving forward and in reverse several times with the same result. When I switched to 2wd, it moved in drive and reverse just fine. Any idea what would cause this? It only has 40K on it and I hardly used the 4WD. With summer approaching would like to get by for now and avoid a big repair bill, but don't want to cause a bigger problem by avoiding the shop.
  • bobby30xbobby30x Posts: 2
    I consider myself a handy guy and I will tackle any job until it comes to vehicles. however, as of 2 weeks ago, I decieded to take my truck in for some clicking noises coming from the left front tire and a ABS warning light on the dash board. I have an independant warranty and thats when I learned that I might as well not have any warranty at all. They covered about 1/2 the total cost ($1100. give or take) for a new tie-rod, a new left front bearing and they would not cover the cost of the rusty speed sensor, oh and then it had to be realigned. Now 2 weeks later, I was driving my truck down the highway and I got a dinging noise and when I looked down at the information center, it said "service 4x4". After I parked the truck, I pulled the fuse to make sure it wasn't the cheapest fix possible and it checked out fine so I replaced it. I started the truck back up after this process and there was no error and I could select 2x, 4low, and 4high. Today, 1 week after initial 4x4 service light, I got in my truck and the 4x4 option panel is lit up as neutral and when I try to select a option, it just blinks and eventually goes back into neutral mode. Is this the actuator or something more extensive? Any opinions would be much appreciated.
  • bruce48532bruce48532 Posts: 64

    11/1/08 - ENCODER MOTOR
    11/1/08 - WHEEL BEARINGS
    11/1/06 - 4WD SELECTOR SWITCH (DASH)
    4/1/05 - FRONT LEFT TIE ROD
  • jbeyhijbeyhi Posts: 6
    You appear to be experienced on the 1999 4X4 Silverado. I had the actuator replaced and 4WD module when the technician said the front axles didn't engage and I could see the 4WD light continue to flash. 2 years later the same symptoms. I think it's a design & engineering defect but GM going bankrupt offers no promise of a permanent solution. I figure it isn't worth fixing if I don't use the 4X4 high. I can get it into low. Additionally the rear view mirror doesn't automatically dim for night driving and the fuel guage sometimes quits working. The dealer wants $thousand$. Would appreciate your advice.
  • bobby30xbobby30x Posts: 2
    my truck is a 2006 chevy silverado z71 non-on-star package.

    now the truck is sometimes ok and sometimes stuck in nuetral even if i never pushed a button
  • alan1818alan1818 Posts: 4
    My experience is limited; however, I did recently experience the loss of 4WD on my '96 Sierra that was resolved by replacing the front differential actuator. I had the same flashing 4WD indicator as you did before replacing it. I don't mean to ask a dumb question, but when you say you still have low range, are you sure the front wheels also are engaged? The transfer case shifts separately from the front differential, so you can be in low range, but not in 4WD. Happened to me, I thought I still had 4WD in low range, but it wasn't until I was on a grassy slope that I found I was wrong. If you want to avoid the dealer, the front actuator is a cinch to change, and was at a good price at autopartsdirecttoyou dot com. My '96 was the older style, but was only $73; I think the later years are still under $100.
  • jbeyhijbeyhi Posts: 6
    You are probably correct but I don't know where to begin, normally I have it serviced by qualified mechanics but the dealer is about the only one here for this problem. I'm too cheap to take it in since the truck drives/runs well otherwise. What books do you use for referrence? Do they have good graphics/pictures? Thanks.
  • alan1818alan1818 Posts: 4
    Actually, I don't have any manuals for this truck, so I generally only tackle the mechanical stuff. Like with the actuator, this forum was great, a little research into what others have done, and the most likely diagnosis, and then the link to the parts supplier showed a picture of what the actuator looks like. I could see where the actuator was screwed in on the differential. The actuator is mechanical, operated through an electrical connection. The only little issue with mine was that the electrical connector wasn't compatible, and I had to splice the old one onto the new part. It's always bit of a chance, just buying a new part, when it could be switches or something else, but the actuator reportedly fails after a period of time, and I knew the low range switches, lights and gears worked. Simple things first. And I guess I was lucky.
  • surrfurtomsurrfurtom Posts: 122
    That's why GM is going bankrupt. They rarely if ever concern themselves with a design fix or a manufacturing defect during a model run.....i.e. 1999 to 2007. The internet is full of the same usually expensive electrical / electronic problems that GM knew about since the late 1999 model that existed on this switch and transfer case motor and also a cable connector as well as many other similar problems (heater actuator, etc).

    I have a 2000 GMC Sierra with very low mileage which just today started the same 4wd symptoms as yours.

    If GM would have attempted to make every vehicle model continually better each model year they would have ended up with super reliability and quality and they could have Americans lining up to buy their products. Instead they continued to do the same thing they've done for 50 years and never make product adjustments or improvements during the 5 or more years of a model run. The customers are forced to deal with the expense and and inconvenience and poor resale.

    The CEO (Wagner, etc) only worried about his jets, bonuses and bennies, not making the best car. Sorry for the rant but every time I think about tax payers bailing them out it ticks me off but not as much as when I think of their incompetent executive management and lack of priorities .
  • krazyk22krazyk22 Posts: 3
    I own a 2000 Silverado 1500 4x4 with 125K miles. Here recently when I accelerate, the truck often revs up into the 3000 rpms, and and sounds like it's going, but the truck doesn't move. I have been assuming it must be the transmission, but could this be something else?
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