3400,v6 engine,my bcm keeps going out,what would make it go out in 5 minutes

2004 OLDSMOBILE ALERO
137 MILES
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JMMJBN
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i can replace the bcm,and go thru the process for the security light with the ign.switch and it all sets up then after startin a time or two the bcm goes back like it was,all lights on dash and gauges come on for 3 seconds then go out and the tach and speedometer do not work.can turn key on and jump across starter,it starts and runs and shifts fine,but no gauges or warning lights.
Oct 12, 2012 at 5:07 PM
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KHLOW2008
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Try checking for trouble codes. Check underhood fuses.
Oct 12, 2012 at 5:51 PM
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JMMJBN
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all fuses are good,can not check codes,will not read codes
Oct 12, 2012 at 5:53 PM
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DOCFIXIT
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Check for voltage on ignition feed connector B terminal 9 pink wire
Oct 12, 2012 at 5:57 PM
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KHLOW2008
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Do you mean the scan tool is not able to communicate?
Oct 12, 2012 at 5:57 PM
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JMMJBN
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scan tool will not show anything,like nothing is there.what is voltage suppose to be on pink wire? will have to get back to you later,as i am at work.
Oct 12, 2012 at 6:13 PM
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KHLOW2008
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Ignition feed is battery voltage.
Oct 12, 2012 at 6:53 PM
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JMMJBN
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i have 12 v at the pink wire,also to the bcm,i have replaced the switch,also have a drain on battery
Oct 12, 2012 at 10:29 PM
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KHLOW2008
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The drain on the battery should be diagnosed and rectified. It could be related to the BCM logging off. It can be some component not turning off, a bad control module or a relay sticking. The link below should be helpful.

https://www.2carpros.com/articles/car-battery-dead-overnight
Oct 13, 2012 at 11:48 AM
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JMMJBN
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the drain on bat.only starts after the bcm goes out,i have checked everything on car and the only thing that checks bad is the bcm.i would like to know the top 10 things that would make the bcm fry in a matter of minutes.
Oct 15, 2012 at 1:11 PM
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KHLOW2008
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A shorting in one of the circuits that is linked to the BCM can cause that. The other would be excessive voltage getting to it.
Oct 15, 2012 at 3:58 PM
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JMMJBN
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the drain on the bat.is pulsing,i can take out the L/H bat 2 bec fuse from under the hood and it stops,what does that run or what might it be, i thank you for all you help
Oct 15, 2012 at 10:21 PM
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JMMJBN
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i found out itis on the ip/hvac fuse inside car,but dont know what that is and book does not say
Oct 15, 2012 at 10:55 PM
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KHLOW2008
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Diagram shows the power distribution for the L/H bat 2 bec fuse and if the IPC/HVAC BATT fuse that is draining, disconnect the HVAC control assy to test if it is the one causing the problem or the IPC (instrument panel cluster)
Image (Click to enlarge)
Attached Media
Oct 16, 2012 at 9:53 AM
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JMMJBN
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what does HVAC stand for and where is it
Oct 16, 2012 at 12:54 PM
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KHLOW2008
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Heating, Ventilation, Air Conditioning - that is the control panel for the A/C heater system.
Oct 16, 2012 at 5:50 PM
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GERGINIST
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Did you find anything out on your dilemma? I am having kinda the same issues, gauges drop to zero while driving, intermittently. Replaced the ignition switch, checked and verified every fuse while setting still and everything working fine. Scanner says no codes. Only seen it error while driving/moving. Above schematic will help, didn't think of HVAC module thrown into the mix.
Nov 24, 2012 at 4:37 PM