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Chevy Silverado and GMC Sierra Electrical and Computer Questions



  • himiehimie Posts: 4
    I disconnected my battery for about 10 hrs. After reconnecting it my factory alarm went off like it did previous times in the middle of the nite. Took about 1 hr after being reconnected before it went off again. Anybody know who to contact about a factory alarm. GMC dealers want $100 to check it out. Trying to save some money if it is something simple.
  • I have a 2004 SS and the left turn signal won't work sometimes. It won't light up any of the lights even the dash and is very sparatic. Won't ever do it when it's in the shop. I have already but in a new turn signal switch which changed nothing. Sometimes you can hear a really clicking really fast.
  • vhdvhd Posts: 2
    Does anyone know how to over ride the system so that the DVD player will play on the riding screen while the truck is in drive..
    Agin this is a very important question so i can watch football while my wife is driving!!

    Seirra Danali 2009
  • I have a 2003 GMC SIERRA PU. Security Alarm will go off anytime. I have tried to disconnect the battery and for a period of time, but still sounds off anytime. Has anybody had this problem and how did you fix it?
  • I have a 2001 chevrolet silverado 1500 and my lights just like yours comes on and stays on I personally have a relative that works at the dealer ship and he too put my truck on a dianostic machine and it gave two codes.The machanic said it was a computer module that went bad so I read your story and I wanted to share it with you....maybe it could be the same problem. Write back to me at Shane
  • I have the same problem, it is in your tilt steering column not the fuses or headlights, I have not broken it down yet to find the answer that is why I looked to here to see if anyone had similar problems, if you raise your tilt all the way up they should come on intermittently, I am not sure if it is a wire degraded from the strain of being bent back & forth or it has some type of contacts since the travel is extensive, but I have had to jar the steering column sometimes to get it to temporarily work, I hope this at least points you in the right direction, I will let you know if I find the permanent fix, is seems it is a common problem with that design & is used in numerous GM vehicles
  • My 2001 Chevy 2500 HD 6.0 liter is misfiring on #'s 2,4,6,8 cylinders and if I understood it correctly it is all on the passenger side. It just happened over night. It came up on the computer as being one of three things. Intake gasket, bad plugs or wires. Had the gasket replaced and drove it home about 7 miles and it ran fine. Sat for two days started it up and it was misfiring again with the service engine light flashing as before. I do have a bad catalytic converter that has been rattling for about 4 months, I don't know if that has any bearing on the problem or not. Thanks for any help.
  • While driving the truck last weekend my dash was reading "Right Door Ajar". My lights were also staying on. A couple times I couldn't get my inside lights to turn off after the alarm sounded until I disconnected my battery. So I took it into the dealership and told them what was going on. They said my switch in the right door was tested and said it was bad, It cost me $427 for parts and labor. It has been 5 days and the alarm has not sounded, and it was happening alot if I had the battery connected. Keeping my fingers crossed.
  • 2007 Siverado 1500HD battery dies when truck is not used for more than 3-4 days, I have had the dealer do many tests and no real answers, the battery has been changed out twice, the truck is optioned up pretty good, so there are a lot of draw functions on it, but the parasitic draws are not out of line according to the dealer, I would like to use a bigger better battery, but the space won't allow this....any one had this problem???, the truck is well maintained, and had about 21K on it
  • if the rattling cat is on the passenger side it may be your problem. if the cat is not burning off unburned fuel the post cat oxygen sensor will read a rich condition and the computer will deliver considerably less fuel to that bank of cylinders causing misfires.
  • Thanks for your response. I haven't had any trouble with the misfiring for a week. The rattling at the cat area has stopped, actually right before the misfiring started. I did get a diagnostic check run on the truck after the intake gasket was replaced and it misfired again and nothing came up, cats are good at the current 77,000 miles. I thot for sure the cats were bad, something was rattling under there and I never could find out what it was, everything was tight. Its purring like a kitten now, I'll keep on trucking. Thanks again.
  • kodak1kodak1 Posts: 1
    just joined this forum hope this helps you it was my problem my battery would always run down on my 06 4x4 it ended up being my windshield wiper motor shorting against the body try unplugging it for a few days. later
  • denhamdenham Posts: 76
    Service Engine Light with Code 440 emission fault, can not seem to find the problem.
    Have checked the wires and plugs, gas cap,etc. The canister is ok, but not sure how to check the purge solenoid? Anyone who has had this problem or idea I can use!
    With the code cleared you can start and drive maybe three times before the service engine light comes back on.
  • shaneoshaneo Posts: 2
    here is your solution unplug the battery for 3mins just enough to reset your truck and pllug back the battery and turn your ignition back on a wham bye bye service engine light.....keep me posted
  • obyoneobyone Posts: 8,065

    The EVAP LARGE LEAK TEST is based on applying vacuum to the EVAP system and monitoring the rate of vacuum decay. The Powertrain Control Module (PCM) uses the input from the Fuel Tank Pressure (FTP) sensor in order to determine the rate of vacuum decay. At an appropriate time, the PCM turns the EVAP canister purge valve ON (open) and the EVAP canister vent valve ON (closed). This allows the engine to draw a vacuum on the system. At a calibrated time or vacuum level, the PCM turns the purge valve OFF (closed), and tests the system vacuum. If the system is unable to achieve the calibrated vacuum level, the PCM will set DTC P0440.


    •DTCs P0107. P0108, P0110, P0112, P0113, P0115, P0117, P0118, P0121, P0122, P0123, P0125, P0443, P0449, P0452, P0453, P1106, P1107, P1111, P1112, P1114, P1115, P1121 or P1122 are not set.
    •The system voltage is between 10-18 volts .
    •The startup (ECT) engine coolant temperature is between than 4-30°C (39-86°F) , but the start up ECT is not more than 8°C (14°F) more than the startup IAT temperature.
    •The startup (IAT) intake air temperature is between than 4-30°C (39-86°F) , but the start up IAT is not more than 3°C (7°F) more than the startup ECT temperature.
    •The fuel tank level is between 15-85 percent .
    •The Barometric Pressure (BARO) is more than 75 kPa .
    •The Vehicle Speed Sensor (VSS) is less than 75 mph .
    The EVAP system is not able to achieve or maintain vacuum during the diagnostic test.


    •The control module illuminates the Malfunction Indicator Lamp (MIL) when the diagnostic runs and fails.
    •The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Freeze Frame/Failure Records.

    •The control module turns OFF the Malfunction Indicator Lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
    •A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
    •A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
    •Use a scan tool in order to clear the MIL and the DTC.

    •Use the EVAP pressure/purge diagnostic station in order to pressurize the EVAP system to aid in locating intermittent leaks.
    •Move all EVAP components while testing with the Ultrasonic Leak Detector.
    •A temporary blockage in the EVAP canister purge valve, purge pipe or EVAP canister could cause an intermittent condition. To repair a blockage in the EVAP system refer to Evaporative Emission (EVAP) System Cleaning. See: Emission Control Systems\Evaporative Emissions System\Service and Repair
  • denhamdenham Posts: 76
    Yes undo the battery will clear the code and the light will go out, but not fix the problem. The gas tank must build up pressure and most often it is the gas cap weak from use and you get the check engine light. This was my problem and I would say that anyone who has check engine light what any type auto they should first replace the gas cap as it could very well be the problem at little cost.
  • 03 1500 silverado..left turn signal will stop blinking when i put foot on brake pedal
  • my gadges go up and down and my batt. light comes on for a couple second and the gadges go crazy, rpm,speedomoder, oil,water temp, alt gadges go crazy and then quit working. does any body knows the problem please let me know. I change the alt. still not working. ray.
  • azjasazjas Posts: 6
    It is the ignition harness causing you all the problems.
    Replace it -
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