Major Help! (Electronics)
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This is a discussion on Major Help! (Electronics) within the General Maintenance, Troubleshooting & Accidents. forums, part of the Tech & Modifying & General Repairs category; I was driving and my electronics acted like my car was off but my engine kept running for awhile and ...

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    Major Help! (Electronics)

    I was driving and my electronics acted like my car was off but my engine kept running for awhile and then started to act up and then stop and start acting up again. Examples of my electronics acting up are: ABS light comeing on... security light blinking... radio turning off... tach and speedo not reading.. I was wondeirng if this was an ECU problem... but when I went to start the car again if would not start... it acted as if the batter was bad... but i tested it and it was fine.. this only happens when it gets cold... I was thinking I might have water accumulation somewhere and it freezes and when my car gets warm enough it melts and shorts things out... any ideas would be amazing!!

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    Registered User EvoEatr's Avatar
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    How many miles are on the vehicle? I would check all your ground connections/connections in general and your Alternator output and also load test your battery...This is where I would prob. start... What mods are done to the vehicle..what is it tuned with?

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    102,000 on it.. Cobb tuned... I cannot remember the mapping had a friend do it with his cobb tuner... But I am going to start with all my grounds like you said and the alternator its just weird it would start up like this when it got cold.

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    A friend said that it could be the security system sensor freezing... is there a way to turn that off?

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    Administrator Trainrex's Avatar
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    I would check your battery connections.

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    thnx for the help but I found a fuel leak too so I am breaking down a bunch of the car now so hopefully i can figure out the other problem at the same time lol!

  8. #7
    Registered User Sarra's Avatar
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    How much charge was in your battery?

    SOME cars have an 'oh crap' mode when the alternator dies (or the belt explodes). Once the battery charge drops to 10.2 volts, the PCM (AKA ECU) goes into "EMERGENCY limp mode", and starts progressively shutting down EVERYTHING in the vehicle that uses power. It'll start by shutting off any other computers in the car, then move on to the Radio, interior lights, power windows on some makes/models, power locks, even the gauge cluster will get shut off. The PCM will increase the injector pulse width to the point where the injectors are basically open as long as they possibly can be, we're talking so rich that 9:1 or richer is par for the course.

    The last Trick the computer has is a rectifier on the 5v reference, which is REQUIRED to run the engine. With a rectifier for the 5v reference, the vehicle very well may run, and drive, even with as little as 2 volts of power left in the battery. Going 15 miles will probably use up around 1/4 to 1/2 a tank of gas.

    Anyway... On to this problem. I would start by verifying the grounds, and then check the power feeds, especially to the computer and injectors.

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    Thnx for the info... so its not beyond the scope that the alternator is going out then... I am thinking it would be wise to change it anyways since my high mileage and I am not sure if the previous owner had changed it or not.

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    Registered User EvoEatr's Avatar
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    Quote Originally Posted by djshortbus View Post
    Thnx for the info... so its not beyond the scope that the alternator is going out then... I am thinking it would be wise to change it anyways since my high mileage and I am not sure if the previous owner had changed it or not.
    Hmmm I would test it first, you dont want to go just throwing parts at it when you dont know the exact cause of the problem..Unless of course you have the funds and would like to...

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    Having similar problem. Did you come to a resolution. Mine happens when it is wet out or if i just washed the car.

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    Well to solve the problem I finally went and got my alternator checked and it was producing enough to start my car but it was going out. So I had to get a replacement one... something that I should have noticed but was not untill later was the fact that my headlights dimmed when i let off the gas... this should have been my first clue that my alternator was going out. Since it was dieing the ECU was going into the above stated limp mode and killing stuff off to keep the car running. I feel dumb for not figuring this out sooner hahahaha! But I did get it fixed and my car runs amazing. So if in doubt check our alternator its easy to remove and u can get it tested at an auto parts store.

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