I took my 2003 TrailBlazer to the Dealer last week to fix the problem
with my 4x4 switch. The Service 4x4 came on 3 times in 2 days, so on my
day off Week before last I had them upgrade my computer to the latest
firmware which fixes that problem according to the TSB. I also replaced
my front rotors and pads this weekend because they were warped from the
PO, but that shouldn't affect brake lights at all.
Yesterday, someone stopped me to tell me that my left and right brake
lights were not working, but my highmount was. I was confused how both
lights burnt out. So when I got back to work, I made sure my signals
worked (lower bulbs), and I used my remote to unlock the vehicle and the
brake lights (upper bulbs) flashed. Everything seemed fine. I had my
wife double check today, and sure enough, when I press the brake, they
don't come on.
So here is what I know... The bulbs work, and have electricity. The
brake lights flash when the vehicle is unlocked with the remote. As far
as I know, no wiring was modified. The foot pedal sensor works because
I can get out of park and the highmount light comes on.
Could the OCM upgrade have done this? Any other ideas? Some strange
fuse for braking only? I'm going out of town tonight and need to know
if I have a right to call and have the dealer fix it before I leave. I
think this would be a quick fix and high priority since it is a safety