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Chevy Silverado and GMC Sierra Electrical and Computer Questions



  • I have a 2004 Silverado 1500 LT. My drivers side seat heater will initially turn off after abt 10 seconds, then wont come on all all after inital turn on. The passenger heater works fine as long as I don't try to turn on the driver side. As soon as I turn on the driver side, the passenger side clicks off. Any clue's as how to fix this besides taking it to a dealer.
  • jeh4jeh4 Posts: 1
    I am having a problem with the low beam headlights on my 1997 Chevy Silverado. The running lights come on when you turn the key or the vehicle is running. If you turn the headlights on the running lights go out and the low beams will not activate, however; the high beams work. If you place the light switch selector on the parklight selection the park lights will activate and the running lights will remain on (basically you have low beam headlights and marker lights). I changed the headlight switch but the problem persists. Does anyone have any advice?


  • azjasazjas Posts: 6
    While driving or while idling, the gauges (all of them) and indicator on my 2000 GMC Sierra SE will suddenly begin to literally go crazy! At times this will cause the transmission not to down shift when driving. I can turn off the truck/or disconnect the battery and the truck will run perfect again (Sometimes for a considerable amount of time. I checked all cables and connection - no problems found. Could this be a bad computer module? Is this an expensive fix? Where exactly is the computer module located?
  • I have a 2005 silverado. I noticed that the parking lights have stopped working. Not completely, but they won't turn on with the park light setting on the headlight switch, nor will they flash like they used to with the keyless entry. They will turn on with the headlights though. I have checked every fuse I could find on the side of the dash and under the hood. Anyone have any suggestions on what the problem may be?
  • chad8chad8 Posts: 9
    I have 01 sierra that has a very strange problem...the batteries(3 so far) I put in this thing leak(or boil) acid and don't last long...I have checked the grounds thoroughly and the cables are in good cond. I have rebuilt the alt. and also replaced it all together just to rule it out. It shows a good charge(not over) on the gauge and also with a meter. If anyone has any ideas they would be greatly appreciated
  • From what I know-experience in a GM parts department and aftermarket parts store, the ABS warning light and brake warning light at the same time may indicate a bad sensor in the ABS system. Due to the many variations within GM. Delco-Moraine, and Bendix these sensors could be located at the rotors, transmissions, or even the differential of the rear end. A computer scan may not pick this up but testing each sensor with a volt/ohm meter will indicate if it is working properly. A "good" mechanic knows how to do this.
  • 2000 Chevrolet LS P/U. A few weeks ago while driving, all of my indicators on my inst. panel lit up and all of my gauges & speedometer spiked up and down. My transmission downshifted and stuck in that gear. After I turn the engine off and then back on it runs perfect again. At night when this happens, I noticed that the gear shift position indicator goes dark. This tends to happen 2 or three times a week. Does anyone have a clue of what the likely cause is? Or where to look for the problem? Any feedback would be appreciated!

    Most likely the same problem described by "azjas" (#148 Intermittent Computer Problem)
  • azjasazjas Posts: 6
    :sick: ronnie, After waiting patiently to see if anyone on this forum would help me, I decided to look into this issue via a local GMC Dealership. I was told that the problem you (and I) are experiencing is likely being caused by a faulty ignition switch or a (ground or open) short in the wiring harness going to a sensor located in the transmission case. Although I have not had money to get my in the shop (Estimated repair cost of about $400 to replace the switch - with no guarantee that this will resolve the problem) - I plan to buy the switch and attempt to install myself - I am told that it will take some patience - but I should be able to do it.
    I just don't have that type of money at the moment, but that's another problem. I am told the switch is about $175.
  • Thanks azias!! I will take mine in armed with this information and post the results of what we do and if it gets fixed. It will be a few weeks before I can take it in.
  • Guys, I have an 03 Sierra. Though I have not had that electrical problem (YET), I have a letter from GMC that they have extended the 03 warranty for 7 years, 70K miles to correct "condition where one or more of the instrument panel gauge needles may stick, flutter or become inoperative. This may cause inaccurate readings, including the speedometer and the fuel gauge". You cannot take the truck in unless you have seen the problem. The dealer is supposed to replace the instrument panel cluster. If you have already paid for this repair, I also received claim form to GMC for reimbursement.
    FYI, during my warranty period they performed the following electrical repairs: alternator (under charge), alternator wiring harness (wild overcharge swings,bulletin PI.73170D), reprogrammed the radio module (no volume, bulletin 02-08-44-020B), replaced airbag sensors upfront, 6 software updates for the 4WD, AC pressure switch (shorted), 4WD drive light on-reprogrammed transfer case module (bulletin 02-04-21-006A).
    And now the wipers won't turn off at times.
  • I have an '03 and also a letter from GMC saying they will extend the warranty for the speedometer issue (new instrument cluster). I don't have the issue with the instruments but do have the problems with the wipers not turning off. The letter says nothing about that, so let me know what you find out. My 03 has been loaded with electrical issues.
  • bigz04bigz04 Posts: 12
    :mad: Good luck. 2004 Chevy silverado Z71 4x4. Speedo started going crazy around 25,000 miles on truck, truck now has 27,000 miles on it and it has been into chevy 5 times! For this Speedo repair, each time two different dealers same part replaced: Instrument panel cluster. Same result no fix, Speedo keeps acting crazy or pegs at zero. But cruise works regardless. Think I'm going to just bite the bullet and try replacing my Vehicle Speed Sensor in the Transfer case. Maybe there is a short or some thing in it? On some days when the speedo acts up I get a Service Brake Booster show up on the screen. All I know for sure is if this does not get fixed soon, I'm going to trade it in for a Dodge and never buy chevy again.
  • azjasazjas Posts: 6
    :sick: Per the GMC Dealership Service Manager - the 03/04 Instrument clusters are defective and will be replaced. Unfortunately, they continue to get replaced with defective units. GMC/Chevrolet is aware of the instrument panel issues for these model years - hence - the free replacement of the clusters.
    Unfortunately for me - this is not the problem with my 2000 GMC Sierra. So far, the best bet we have in repairing intermittent gauge spikes and a transmission failure appears to be a faulty ignition switch or short in a wiring harness that leads to the transmission sensor.
  • man, you wanna talk about angry!!!! I woke up this morning at about 6:00am to my beautiful 08' model 3500hd LTZ crew 4x4 dually to hook up to my gooseneck and it fired up just fine.Gave her about 15 minutes of warm up time before backing out of the barn with her and as soon as i stuck in reverse all #%@@ broke loose. i got a check airbag, check 4x4, and a check trailer brake system. i shut it off then tried to restart and it wouldnt start. to make matters worse i hotshot for a living and just lost on a nice little $1000 run. i had to call the tow truck and cried when i saw my brand new baby rollin away from me. oh, by the way she only has 3800 miles on her. anybody ever experience this?
  • still looking for any tech support on this issue. i took my truck in the dea, i'm sorry, the tow truck towed my new duramax into the dealership this morning and they called me about an hour ago and told me it would be untill 10:30-11:00am tom. before they even look at it. just stressing alittle bit because livleyhood depends on truck.i guess nobody is off from their 9 to 5 yet.any help to put me at ease would be appreciated. thanx
  • Hi, I hope someone can help me out with this. I have a 2003 Sierra 2500 HD 4X4. My truck sometimes goes into 4X4 (I can put it back into two wheel) also it sometimes goes into tow haul it does this when I start it and I put it into gear it does it on its own. Also sometimes the radio shuts off then will come back on the next time I start the truck. The lights are dim and will pulse at night. The battery will go dead sometimes; and nothing is left on. I'm thinking that it might be wiring. :sick:
  • azias,
    Update on our issue:
    Had a mechanic replace the ignition switch and so far so good. Seems to have fixed the problem. It was acting up several times per day before.
    Delco P/N: D1422D @ $89.90
    Labor was $125.00 (not too bad)
    It looked like it would not be too difficult to replace?
    The mechanic told me that the previous years switch assy were ~$200.00. He was shocked that mine was that less expensive.
    Good luck!!
  • azjasazjas Posts: 6
    That is GREAT News! Congrats! I hope that I will have the same GOOD LUCK! Still saving some pennies, nickels and dimes to get the repair on mine.
  • This is very disturbing to hear...
    We just bought a '08 2500hd for my son. Pulled it out of the dealership, and less than 2 miles down the road, the ABS, Brake waring light, and "Trailer Brake System" lights all came on. We drove it right back and left with a loaner Grand Prix. Next day, we tried again and made it a half mile before the lights came back on (additinally, the blinkers wouldn't go off). Third times a charm right? Three Miles!!!
    Is there a known electrical problem with these trucks? If so, our dealer doesn't seem to be aware. I am afraid my son will get his first payment statement before he actually gets the truck home.
  • A search on the internet, shows that these problems are prevalent. The fact that GM and dealers are acting like these are isolated cases, is what is turning me against GM. I have been buying and driving GM for 30 years. My 03 was/is loaded with silly electrical issues and they continue. The flimsy engineering on the power mirrors, power widows and power locks is embarrassing. I feel like I am driving a chevette vs a Professional grade truck! With only 45M miles, in the past 2 weeks of winter, my heater fan failed on positions 1-3, my windows would not roll down, and passenger door lock would not unlock (cold weather and ice). Kind of poor for a truck that was supposed to be designed for winter. Have already had 2 power windows fall apart. Wake up GM! This is why I am not trading in I am not convinced that any of these problems have been fixed, all I see is another new grille!
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