What is causing my electrical issues?
I have a 2004 Chevy Avalanche. I recently installed
LED headlight bulbs, and afterwards started having
all sorts of electrical issues that I never had before.
I changed back to Halogen bulbs but the issues
remain. Since the issues began, I installed a new
ECU flashed to my vehicle. The issues I have is,
turn signal lights flickering, turn signals and
reverse lights intermittently work, 4wd, ABS and
parking brake warnings intermittently, horn no
longer working, door switches for the adjustable
pedals and heated seats not operational,
occassionally the entire instrument panel goes off
and comes back on, and intermittent loss of key
program or security light coming on. I am thinking
possibly the BCM requires replacement, but am
also unsure if the BCM will need to be flashed (I
have heard both yes and no). The vehicle also
occasionally loses power or will stutter.
Check the alternator or have it checked.
Could be a bunch of things of course but sounds to me like weak electrical connections somewhere. I'd check, tighten and clean every connection you can find including all grounds. Make sure its charging properly as has been mentioned and load test the battery. Some of the symptoms made me think of signal light switch and clock spring, but others definitely don't. I believe the dealer or better equipped auto electric service shops can scan and diagnose the BCM and I'm reasonably sure that replacing it requires dealer programming. Just throwing out ideas. Hope something here helps.
I have changed the Alternator (original was working, but went to higher amps due to accessories), new belts, checked every single fuse and installed a new Light Control Module. This is on top of the new, flashed ECU and the new BCM. Next step is of course to have the dealer flash the new BCM. The only issue I could see at this time is the ground strap is corroded, but again, as there were 0 issues previously and this occurred at the exact same time I installed the LED headlights, I believe it has to be something was shorted. I've added a photo of the alerts. Another oddity is that when my headlights come on, all 4 illuminate, with only the driver side low beam being bright. Turn on high beams, all 4 stay illuminated, but the high get brighter. Also, the turn signals now only do not work when the headlights are on.
That does certainly sound like a bad ground somewhere or possibly a short of some sort. I agree the new lights or at least the work being done to install the new lights seem to be the culprit. Either something got damaged or the difference in current flow pushed some marginal connection or ground over the edge to failure. It sounds like you're pretty capable, but if you've run out of ideas this might be a good time to spend a few dollars at a shop that specializes in auto/truck electrical. Some of those guys, along with their specialized tools, have magical powers when it comes to sorting things out. You've done the heavy work, I'm guessing finding the final problem now may just need a fresh set of eyes. Good luck.
