I have scoured the intertoobs for advice and am coming up blank. I have no brake lights (Left, Right, or Center) but all other lights are operational. Fuses checked, double checked, triple and fourple checked. BPP sensor replaced (probably unnecessarily so) and getting power/sending power when pedal depressed. I hear a lot of vague talk about the REM, but it would seem to me that if it were the REM, then none of my other lights would be working.
Help!
Does your cruise control work? The reason I ask this question is that the cruise control operates through the brake light switch. Take the car out on the road and try the cruise control. If it comes on, touch the brakes to see if it comes off. If it doesn’t function as it should, I would suspect the brake light switch. If the cruise control works as it should, then you can eliminate the brake light switch as a possibility. If the brake light switch is functioning, then I would suspect the multifunction switch that controls the turning signals.
Also, with the newer light bulbs, the ground is in the wiring harness. Check for voltage at the socket using a body ground, then check the socket ground for continuity to body ground.
Cruise works just fine. I am curious, though, as to how the multi function switch might be the cause. Im no expert and all the other functions of that switch seem to operate just fine.
When you turn on a turning signal, say the left signal, and then step on the brake pedal, you want the left signal to keep blinking, but the brake lights to illuminate. Thus, the brake lights have to be able to function with the turning signals. This is assuming that the brake lights and turn signals use the same filament in a two filament bulb where the other filament is the tail lights. I remember working through this when I installed turning signals on my 1947 Pontiac (cars back then didn’t have turning signals as standard equipment). That I why I think the multifunction switch may be involved.
The signals are a separate, amber lamp. As for the grounding of the bulbs, it is my understanding that the lamps are, in effect, constantly powered and grounded by the REM when the brakes are applied. If that is correct, wouldnt ground be impossible to check for continuity ?
Since the middle brake light isn’t working also and is on a separate power circuit this points to the Rear Electronic Module. The common tie here is, there is a switched power input on that module that comes from the brake pedal switch and goes to pin 13 of the module via a red/LT green wire. See if you have power on that pin when the pedal is depressed. If you don’t have power there it may be due to a bad splice in the line at S332 (you will need some factory wiring info to locate that splice point). You could apply power to that lead to verify the module operation if that is the case.
The design for the rear lights is kind of interesting. There are separate relay controlled power sources for each side and also a separate light on each side that crosses over to the opposite power source. This gives some redundancy to each of the lights in case one side has a problem.
What you describe sounds like there’s a problem with the REM.
But here’s the kicker. If it is the REM, a dealer type scanner must be used to upload the programming from the old REM so it can be downloaded to the new REM.
Tester