Question about 2003 Chevrolet Silverado 1500

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Electrical problem I've been having electrical issues with my truck. Every couple days, I'll be driving the interior and exterior lights will flicker, the environmental controls will go haywire (start and stop blowing repeatedly), I'll get odd warnings flash on and off (service brakes, service airbags, etc.) The truck still seems to perform well, though. I'll stop and turn the key off, and immediatly lose all power: no auto locks, lights, no starting, nothing. It will get power back about a day later and work fine for another couple days. I just replaced the battery about 3 weeks ago, checked its connections and cleaned it, its all fine. When I disconnected it, it was sparking, so it still has a complete circuit. In the months leading up to this I noticed that every once in a while the clock would reset itself. I assumed that was due to the cold weather (-40) and a bad battery (which is one of the reasons I replaced the battery) but I'm not so sure now as I think it did it once with the new battery as well.

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  • chrism1524 Feb 05, 2009

    You might be onto something... I traced it down to the block and found that there is some duct tape around the harness at the connection to the connector. It seems a little loose, but I couldn't get a close look at it. I'll have to bring it into the shop and put it up on the ramp at lunch and take a good look at it..

  • chrism1524 Feb 05, 2009

    no, the ground wire is good, the tape was just heat tape for the area close to the engine. I cleaned everything up though when I had it out. I reinstalled it and I have power right now, but it doesn't want to start. It'll turn over just fine but it doesn't fire up. I'm thinking the fuel pump is the problem now... checked my fuses and their good, so I'm gonna have to check my fuel pump now, I imagine

  • chrism1524 Feb 05, 2009

    I can't hear the fuel pump and neither could another guy when I had the key on. I'm just about positive thats why it won't start. I'll have to double check it for sure, and probably check the plugs for spark as well. I'm just not sure if thats my complete problem or not. I'm wondering If I don't have a fuel pump problem in addition to the electrical problem (which could possibly be explained by the BCM) or if the electrical problem caused the fuel pump to fail.

    I don't think the engine was turning on and off, as it seemed to have lots of power and I didn't notice any decrease in power when the lights were flickering.

    The warnings I was getting (air bag and brake) apparently are warnings that come on after a decrease in amperage. as soon as they get less than 13 amps they send out a warning.

  • chrism1524 Feb 05, 2009

    what kind of warnings did you get when your fuel pump failed? I've got no warnings or warning lights going off right now when I have the key on.

  • Mark Egan May 11, 2010

    When the fuel pump failed, I was coming back from getting a state inspection (Texas) on a coolish, cloudy Saturday morning, and we were headed to a wine fest for the weekend. I'm 2 blocks from home, and loose power, and power steering, and all kinds of lights light up on the dash, along with the message center that didn't tell anything except I didn't have any power. Anything related to that circuit was dead as it blew the fuse as well. I got it puled over, made a call to a friend, and he said to check the xyz fuse, that there are two of them, one labled xyz 1, the other xyz 2, and the xyz 2 is the fuel pump. He was working at a dealer at the time nd said they got quite a few of them come in with the same problem. I put another fuse in (there's a spare in the box) and got about 20 feet when it blew. Towed home, ordered a fuel pump, and fixed after wine fest.

    Check your fuel rail pressure! If even to bleed it off to see if you can hear the pump run before starting the engine.

  • Mark Egan May 11, 2010

    Fuel pump failed on mine in 2003. No aftermarkets then, so $285.00 and drop the tank. And mine failed dead, no warning, no nothing. Loss of P/S, dash lit up, buzzer's sounded, you would have thought we were the Titanic just as it hit the iceberg.
    But there was a blown fuse to give some initial indication. Your seems to be giving similar signs, except for the interior lights flickering. Do you think maybe the engine is intermittently dying, causing all the lights, then starting back because it's still turning, back driven through the tranny?

    There should be a port on both fuel rails that you can depress to check for pressure. Doesn't guarantee it's enough, but tells you if it's there.

    Let me know. This is getting interesting. And the suggestion to reset the ECM isn't a bad idea, although I think a trip to the library may be of great help there.

  • Mark Egan May 11, 2010

    Cool! Let me know.

  • Mark Egan May 11, 2010

    Did you check the ground cable connection all the down to the block, or wherever it connects to the chassis?
    Check the actual connection where the wire and connector are crimped or bonded together. It may look good on the outside, but be a bad connection.

    It certainly sure sounds like your having a ground problem, and if you cannot see a problem in the battery ground, then I would find a copy of the Factory Service Manual (not Hayne's or Chilton's or Motor's) at the local public library. They are are specific to the year model of vehicle, and give all the dealer troubleshooting guides, as well as connection points for wiring within the vehicle.

    Reply back what you find or if you have additional questions. I know how difficult things like this can be without having someone to bounce thoughts off of.

    By the way, I have an '01 Tahoe, and have reviewed the FSM's for various issues I've had, so I've got familiarity with the chassis and body that you have.


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  • 24 Answers

Possible bad Body Control Module (BCM)...

Posted on Feb 05, 2009

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