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Chevy Silverado and GMC Sierra Electrical and Computer Questions



  • gw1998gw1998 Posts: 6
    Cannot figure out why the back brake lights aren't working on my 1998 Cadillac Catera. ALL fuses are good. ALL bulbs are working. ALL lights work except the brake lights. I put my foot on the brakes..nothing happens. I recently had a new radiator installed. Did they hit a switch or an electrical wire under the hood? The brake lights were working before I had the radiator installed? I hope it's something simple. As soon as I get them working...I'm selling ASAP.
  • just bought 1997 1500 ex cab airbag light on Does anyone know how to resrt it thx
  • KCRamKCRam Mt. Arlington NJPosts: 3,516
    Since this is a Chevy Silverado/GMC Sierra discussion, you'll get a faster response asking in Cadillac Catera: Maintenance & Repair

    kcram - Pickups Host
  • takctakc Posts: 1
    have same code and condition.have u come up with fix
  • deducerdeducer Posts: 2
    '97 GMC Sierra 2500 all brake and tail lights intermittently burn out (black bulb). Is this due to a voltage/current spike?
  • malbitzmalbitz Posts: 4
    I just bought a cap for my 07 Silverado NBS. On the other trucks I have owned there was a wire ran to the back of the truck for the third brake light on the truck cap. On this truck, the cap dealer said there wasn't a wire. If you use the wire in the tail light, the 3rd/eye level light will blink with the driectional signal. The two local chevy dealers have not been able to get an answer for me. Has anybody ran into this? Or do I need to run a mire from the front of the truck.

    Thnaks in advance for your help.
  • geo9geo9 Posts: 739
    I don't see why you can't run a wire/splice off one of the

    Anyhoo........What about running a tap wire off the trailer
    plug or the bundled wires behind the rear bumper?
  • malbitzmalbitz Posts: 4
    Taillights will cause the brake light to blink with the directional. There is not a brake only light (that I can find). If you have the brakes on and turn the directional signal on, both bulbs blink. In the trailer connection, the only output not affected by the directional is the Electric Brakes. But I don't know if there is a reason the dealer didn't use that one. Does anyone know if it is variable on the power output for the trailer brakes.

    I will look for the bundle of wires to see if I can find that.

    Thanks for the info.
  • jaselvisjaselvis Posts: 1
    I have two problems, first is the power window on the passenger side quit working last summer and then this winter the drivers side quit. When I push the button to operate the window there is no blink from the dash lights to indicate a power draw. Fuses check good and wires look ok. Second problem, the truck has a five speed fan and the first two speeds are not working. Blows fine on 3, 4, 5. I read somewhere that it could be the blower motor harness ? Thanks for any help.
  • obyoneobyone Posts: 8,054
    There are diodes that need to be replaced for the first two speeds on your controller. You will need to remove the front face panel of the a/c control to get to the diodes. Or you could do what I did and bought a replacement on ebay for $30. diodes are cheaper tho...

    If you have a meter you can check for power to the power window motor. Odds are that the motor is dead. Famous problem for the GM trucks. So much so that they stopped shipping the motor and controller together due to the high failure rate of the motor it was starting to cost too much money so now they sell just the motor without the controller.
  • obyoneobyone Posts: 8,054
    If you really want that bulletin you could get it for $14.95 at

    Just subscribe to your truck's year and it will list all 120 TSBs out on your truck. Who knows you might find other items of interest.... ;)
  • I issues started with a gage cluster going bad which I replaced about a year ago About six mouths age my heater fan started to cut out every once in a while seeming to draw on the system and to the point of reducing the idle and almost stalling out the eng. At the same time just once I tried to start the truck and when I turned the key I just got some clicking and the gages went a little crazy. After replacing the blower things seemed fine. Just last week the same starting issue has started up and even a low rough idle. I am not sure what to do but I know the dealer will just tell me to bring it in when it is having the problem. One other thing that is going wrong is my trailer tow will not activate I am a little werrie that I am driving a time bomb
  • bmli111bmli111 Posts: 2
    I have a 1991 GMC Sierra. Everytime I brake one of my 4 lights light up. MY taillights work. My right turn signal doesn't work either. I changed the bulbs. What can this be?? PLEASE HELP!!
  • My guess would be a bad turn signal switch. You will need to pull the steering wheel and check it out. It's not that hard. Good luck.
  • dolphan456dolphan456 Posts: 3
    When you checked the wiring, did you check the junction board which is under the bed. The wiring bundle comes back from the front into a junction board and then is distributed to the lighting clusters. These connections are subject to water intrusion which corrodes the contacts.
  • 488488 Posts: 9
    Looking for the brass plates/bushings that connect the wiper motor and the arm that transfers
    motor movement from the motor to the base of the wiper arm. 1990 and 1994 have the same set up. The plates unbolt form the transfer arm BUT
    gm will only sell the complete arm. A $5 part ends up costing $50 plus. So far no luck with the local jobbers.
  • cougartwincougartwin Posts: 1
    Yesterday morning my 2006 Silverado 3500 Duramax 9,900 miles,,,, would not start. GM had it hauled to the local dealership. Diagnosis was "LOT ROT" of the batteries. The service manager explained to me that the salespeople are "supposed" to start every vehicle every few days. If they fail, then the batteries drain. Their remedy is to get the battery cart and cables then jump start the vehicle. After this occurs several times, the batteries fail,,,,,,,, thus,,,,, LOT ROT. The dealership replaced the batteries. No charge. My concern is,,,,,,,, after all that "monkeying" around with charging,,,,,,,,,, have other components been weakened??? There are a lot of computer modules etc. This may be the beginning of several incidents. I am considering purchasing an extended warranty. I love this truck. I've had new Dodges, Fords, all diesels,,,,,,this one is the best. Thanks for your time. Cougartwin
  • 1offroader1offroader Posts: 208
    I'm no expert on diesels, but the electrical systems shouldn't be that much different than a gas pickup. In fact, they should be more heavy duty.

    That said, normal battery charging should not damage an electrical system. All you are doing is running a current to battery terminals, and cables, that normally produce such as current.

    Batteries die because they don't like to be run all the way down. I'm sure there's a physio-chemical reason for that but I don't know what it is.

    I would have the alternator/charging system checked just because a weak system could have caused the batteries to get run down. Otherwise don't worry about it - that's my advice.

  • flysprayflyspray Posts: 15
    Where did you find a cap for the NBS 07 silverado... Ive looked and couldnt find any. My truck should be in real soon. I ordered a cap from the dealer... and they are not available yet. I also have a question about the lockable tailgate. Does the factory lockable tailgate work with the keyflop???
  • malbitzmalbitz Posts: 4
    Century Truck Caps is where I got the CAP (Ultra). Leer also makes one for the 2007 NBS (100 R) or something like that. Also Glasstite had one at the time I bought mine.

    I do not know about the lockable tailgate. Sorry.
  • marcb2marcb2 Posts: 9
    I have a problem with my right turn signal that has gotten worse since I bought my 2003 Silverado 1500. Now, a majority of the time when I turn on my right turn signal, both the left and right blinkers come on as if I had turned on my hazards. Any suggestions on how to fix this or where the problem might be? Please feel free to e-mail me at with Turn Signal as the subject.
  • Last week my truck started having electrical problems. When starting the truck after the engine started, you would hear a whirling sound in the dash, similar to the ventilation "switch" inside the dash, then a quiet thud, and the clock would reset on the radio (standard issue radio - AM/FM/CD). That happened 3 or 4 times and stopped. This morning I was driving and all my gauges went dead as if the truck was shut off. The heads-up display still showed "instant mileage" (love to watch that) and all gauges were dead. I stopped, shut it off, browsed the manual stupidly thinking in might be a fuse. I restarted the truck and it's fine. What's up with this? I love my truck, but it seems possessed with an electrical gremlin.
  • jolazanjolazan Posts: 1
    Have you been able to resolve the problem yet? I have a 2004 Silverado (just out of warranty of course) on which the same thing just started happening... Any input is appreciated.
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