some lights stay on even after key is removed

JackC

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Make
Chev
Model
Tahoe LS
Year
2004
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136,000
Engine
5.3 LS
My daughter, that is 3 hours away, has this problem .

Intermittently, after night time driving, with the automatic headlamps on and then turning off the engine and removing the key, getting out and locking the doors with the fob, the automatic headlamps go off but the parking lights and the backup lights and interior lights stay on.

After trying things like turning lights off and on , starting the engine and turning it off and on, opening and closing the door messing with the fob they finally go out.

Also the right side interior map light will not go out or goes on and off by itself. This may simply just be the switch and not be related to the above problem???

Any ideas?
 

billr

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I sent you PM.
 

JackC

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Maybe the BCM?

The body control module (BCM) supplies battery positive voltage to the individually controlled lamps. In the event that any of these lamps were to remain illuminated for more than 10 minutes with the ignition switch in the OFF position, the BCM will deactivate the inadvertent power supply voltage circuit to prevent a total battery discharge condition.
 
Last edited:

billr

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Could it be something to do with the BCM? Sure, it could be. You know this is not likely to be fixable without a meter and schematics in hand. You gotta tell her to come for a visit; maybe even trade cars for a while.
 

JackC

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I studied several wiring diagrams today with my son in law, an electronics tech , and we think the problem is the BCM.

As a further test, I will have her not use automatic headlights but simply use the off-on switch. If that works for a few months, she will live with it because the BCM and re-programing are pricey.
 

grcauto

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I studied several wiring diagrams today with my son in law, an electronics tech , and we think the problem is the BCM.

As a further test, I will have her not use automatic headlights but simply use the off-on switch. If that works for a few months, she will live with it because the BCM and re-programing are pricey.
What you may have is a door or other switch that is causing the problem and not the module itself.
 

JackC

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I would like to unplug and reinstall the 6 or 7 plugs on the existing BCM to possibly clean up any poor conections. Can they be removed and reinstalled without having to reprogram the BCM?
 

grcauto

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I would like to unplug and reinstall the 6 or 7 plugs on the existing BCM to possibly clean up any poor conections. Can they be removed and reinstalled without having to reprogram the BCM?
The module will hold it's memory and programming so long as the EEPROM is not messed with. Be careful with the data lines they can mess up the memories if messed with.
 

JackC

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The module will hold it's memory and programming so long as the EEPROM is not messed with. Be careful with the data lines they can mess up the memories if messed with.
Thanks grcauto , I am ultra caucus, which is why I asked. I am 89 yrs old and my General Motors Institute training goes back to the '50's. I used to come here to help others and now I come here to learn.
Are there any U codes?
Hi nickb2: Good point. She has friends at the Chev service dept. and an automotve instructor that may help her check for U codes.
 
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