Brake lights not working after OCM upgrade

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 issue.
Thanks!
-- Mike Brancato
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I had a similar problem with my brake lights. it turned out to be the speed sensor for the anti-lock control.

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You sure it's not the parking lights that flash when the RKE is used? I THINK I remember a bad hazard flasher switch doing this. Also check the fuses, pretty sure there are some, though they're different ones for left and right lights...

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Heres the real fix, Trailblazers have a prpblem with the circuit boards in the tail light. Chev. has a special replacement policy on them. It will be taken care of by warrenty.
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Zonie you just beat me to it, but both at the same time? Could be I guess.

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Its rear tail light socket boards. I do about 3 or 4 a week. The design isn't the best. What keeps the bulbs from lighting is oxidation buildup on the contacts. This is because the socket board doesn't hold the bulb when you snap it in very well. The bulb will move slightly in the socket while driving causing oxidation to build up on the contacts. After a while, the buildup will be so much that it will block electrical flow, which is why you have power at the bulbs but no bulb operation. The fix is to replace the rear sockets boards and bulbs. Its a VERY common problem. Your lights work one day and not the next.
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Jason E.
ASE Master Technician with L1 Advanced engine performance
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>> (2003 TrailBlazer has brake light problems.)
Maybe your vehicle has been recalled for this problem:
*** *** ***
GM recalls 1.5 million vehicles in North America Automaker to fix tail lights, sticky accelerators in SUVs, cars Updated: 3:00 p.m. ET Nov. 4, 2004
The recall of nearly 1 million SUVs includes the 2002 to 2004 model-year Chevrolet TrailBlazer, TrailBlazer EXT, GMC Envoy XL and Oldsmobile and the 2004 Buick Rainier.
Vibration and heat may cause the rear brake and turn signals to stop working, Adler said. The recall includes 871,473 of the SUVs in the United States. GM had given owners a six-year warranty to cover that particular problem before issuing the recall, he said.
Despite the high number of recalls this year, GM repeatedly cites independent studies that show its quality improving.
http://www.msnbc.msn.com/id/6408966 /
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