You are here:

GMC Repair/2003 monte carlo electrical problems


I've just started to have a problem with my day time running lights. the high beam indicator light lites up on the dash cluster and flashes on and off, causing the lites to flash on and off. this has not happened at night, as of yet. this seems to happen when the car sits in the hot sum during the day, cause the next morning there are fine again. checked all wiring and its all fine. could this be connected to the bcm. my security light also comes on at different times, but that's been doing that for a long time. for now I removed the high beam bulbs  so I won't be driving with the dash light still flashing on and off.
please advise if you can.. thanks

Dear Wayne,

I would agree there is a good possibility it is related to your BCM.  Computers tend to be temperature sensitive.  I'm glad you mentioned your security light, because those systems are highly dependent on precise voltages being sent to the BCM when certain things happen with the car.  That makes me think that a compromised body ground could be the problem.  This may not be the case but I've seen it cause symptoms like that before.  Look at the negative battery terminal.  There are 2 cables coming from it usually, one going to the engine block and one going to the body.  The voltage going to your BCM, interior electronic systems, lights, etc are all dependent on the ground to the body from the negative side of the battery.  I spent two days once trying to mess with the lights and bypass the security system and finally saw the bad ground and fixing that made everything right.  I just took it off, cleaned the contacting end of the cable and place where it connected really well with a power wire brush, hit it with WD-40 and tightened back on.  That's about the extent of my knowledge for symptoms like that...if your ground is already in good shape then you may want to substitute another BCM to see if the symptoms continue before buying a new one.  Best of luck to you.  Cool car too!

GMC Repair

All Answers

Answers by Expert:

Ask Experts


The Man of Steel


I will take a shot at anything. This service is free, it's worth a try. Please rate in terms of my willingness to help if I can.


Mechanic for 20+ years

AAS Degree in CAD, life experience

©2017 All rights reserved.