Firebird's computer keeps resetting itself after its parked overnight

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    Author Topic: Firebird's computer keeps resetting itself after its parked overnight  (Read 2240 times)

    Offline Scatterbrain

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    Firebird's computer keeps resetting itself after its parked overnight
    « on: March 12, 2009 - 03:16:08 PM »
    I know this is one of those Not a Mopar questions, but this forum has always been the best place for information about alot of things.

    My 99 Firebird started doing some strange electrical things. It all started months ago, after about a week of just sitting in the garage (while I drive my Chally of course) I would start her up and notice all the gauges would come on move to the end and come back, all the lights on the dash would go on and the trip meter would reset itself to 0.  This is normal behavior when I pull the battery, trouble is I hadn't pulled the battery in that time.  The radio wouldn't work until I pulled the rear connectors and it would "reset" itself.  I didn't think the 2 were connected, so it would do the gauges thing every now and again, but the radio would go out almost every week.  I replaced the radio (been wanted to do that for awhile now it was an awful 7 inch TV screen with no dimmer that looked horrible in the dash and would light up your face at night).  Now so far the radio has never shut off, but the last 3 mornings I turn the car on the gauges do their dance.  Battery is showing normal 12v when off and normal 13v when running.  Car starts and runs just fine.  Voltage meter shows normal charge when running.  I do have an aftermarket Autopage alarm that is super sensitive (even turning on my Chally will set it off), I know that if it would go off that could sometimes cause the previous radio to do its shutdown thing but not always.  Could the computer being going out?  The battery dying?  The alarm needs to be replaced?  I have no idea where to start on this one.  Would it even show anything if I had the codes pulled from the computer or would they have been wiped out with the morning reset?
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    Offline Bullitt-

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    Re: Firebird's computer keeps resetting itself after its parked overnight
    « Reply #1 on: March 12, 2009 - 03:51:12 PM »
    Not that I know anything about firebirds but electronic problems in general sometimes can be resolved by simply powering down & re booting, so to speak.   
    disconnect the battery for a while & see what the result is....you never know till you try.
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    Wade  73 Rallye 340..'77 Millennium Falcon...13 R/T Classic   Huntsville, AL
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    Offline quagmire

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    Re: Firebird's computer keeps resetting itself after its parked overnight
    « Reply #2 on: March 12, 2009 - 07:26:37 PM »
    Three big things come to mind:
    1.  Have the battery load tested, if it is weak and voltage dips too low while cranking it may cause the IPC to lose its flash memory.

    2.  Test for a power drain.  Most GM's and other late models have a Power Management Mode that will turn off accessories or other circuits if the BCM times out, a door trigger is set, or if the voltage drops too low.

    3.  There may be an issue with the BCM, IPC, or Class 2 data bus.  I doubt it however, I'd put my money on the first 2 tests showing something. 

    I think the trip odo, gauge reset, and radio are all interrelated.  Most likely from a weak battery or a parasitic draw (possibly from an amp, radio, alarm, or many other circuits staying powered up.)  If this is a stock radio, the theft lock system in the radio can trigger if the power dips too low or is removed, many newer GM vehicles have the radio programmed to match the VIN stored on the BCM and PCM.  It gets this info on the Class 2 or E&C data bus.  The IPC stores gauge sweep and trip odo info on flash memory, and it too will lose this if power is lost.  Even if it is an aftermarket radio, test the battery and current draw.
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    Offline 73Chally

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    Re: Firebird's computer keeps resetting itself after its parked overnight
    « Reply #3 on: March 12, 2009 - 08:20:32 PM »
    Quote from: quagmire on March 12, 2009 - 07:26:37 PM
    Three big things come to mind:
    1.  Have the battery load tested, if it is weak and voltage dips too low while cranking it may cause the IPC to lose its flash memory.

    2.  Test for a power drain.  Most GM's and other late models have a Power Management Mode that will turn off accessories or other circuits if the BCM times out, a door trigger is set, or if the voltage drops too low.

    3.  There may be an issue with the BCM, IPC, or Class 2 data bus.  I doubt it however, I'd put my money on the first 2 tests showing something. 

    I think the trip odo, gauge reset, and radio are all interrelated.  Most likely from a weak battery or a parasitic draw (possibly from an amp, radio, alarm, or many other circuits staying powered up.)  If this is a stock radio, the theft lock system in the radio can trigger if the power dips too low or is removed, many newer GM vehicles have the radio programmed to match the VIN stored on the BCM and PCM.  It gets this info on the Class 2 or E&C data bus.  The IPC stores gauge sweep and trip odo info on flash memory, and it too will lose this if power is lost.  Even if it is an aftermarket radio, test the battery and current draw.
    I would put my money on number 1.  I have an '05 Town and Country that spent a good bit of this winter up in New York.  I noticed that the gauges started doing the exact same thing yours are, along with all the lights coming on, and sometimes I would hear the CD changer cycle, and it would all happen just after the engine would start and I would release the key to the run position.  After the next below zero night, the battery was dead.  After replacing the battery, it has not happened since.
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    Offline Scatterbrain

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    Re: Firebird's computer keeps resetting itself after its parked overnight
    « Reply #4 on: March 13, 2009 - 11:39:35 AM »
    Well the time between resets is getting closer.  It did the rest thing when I turned on the car yesterday when I went home from work.  Usually it takes overnight to do it.  I checked the voltage on the battery when I got home at it was at 12.4.  I checked it this morning and it was at 11.8-11.9.  I figure the alarm will draw some electricity, but it shouldn't be that much.  I jumped in and cranked it and it did the reset.  I figure it is the original battery that is coming close to 10 years now might as well replace it.  So I drove down to O'Reilly's Auto and swapped it out with an Optima red top... just wish it wasn't raining when I did it. 
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    Offline heminut

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    Re: Firebird's computer keeps resetting itself after its parked overnight
    « Reply #5 on: March 13, 2009 - 02:37:16 PM »
    The new battery should solve your problem. I had problems with ECM reset in my 99 Dodge Ram. I took the battery to Autozone and had a load test done. The battery was shot, even though it showed a little over 12 volts before the load was applied. I put a new battery in and the problem went away.
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    1970 5.7 Hemi Cuda

    Offline 72bluNblu

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    Re: Firebird's computer keeps resetting itself after its parked overnight
    « Reply #6 on: March 13, 2009 - 05:47:31 PM »
     :iagree:

    Sounds like a battery problem, although it may just be dirty terminals or a bad connection to battery power somewhere in the system.
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    Offline Scatterbrain

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    Re: Firebird's computer keeps resetting itself after its parked overnight
    « Reply #7 on: March 19, 2009 - 01:55:17 PM »
    Arg...  :pullinghair:  Just got back from lunch and after about a week of behaving itself it reset itself when I started it up coming home from the restaurant.  And then as a test, I turned it off and restarted it in the parking lot where it reset itself again.  Not the battery, I guess I've got some work to do with a multimeter this weekend.
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    Offline burnt orange

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    Re: Firebird's computer keeps resetting itself after its parked overnight
    « Reply #8 on: March 19, 2009 - 02:55:39 PM »
    I hate electrical bugs in newer cars!   :swear:
    Any electrical problem in our Cudas and Challengers are usually easy to solve and a quick, inexpensive fix.
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    Offline quagmire

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    Re: Firebird's computer keeps resetting itself after its parked overnight
    « Reply #9 on: March 19, 2009 - 08:13:17 PM »
    Have you done the parasitic draw test yet?  If something is draining your battery you will be replacing the current one in short order too. 
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