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Re: 1992 High Mount (inside glass) 3rd brake light bulb pn#
Five years later ...
I just got around to removing mine. It is the original bulb to the extent that I have always owned the car and I've never replaced it. It has been inoperative for decades. As I age I tend to think more about getting hit from behind. The two screws holding the black plastic cover plate are removed with a Torx T-15 bit. There is also a number 20 stamped on the base (picture), although I don't know the significance of this number, or that it even matters. The bulb is apparently not readily available on Amazon or eBay. I see the LED versions there and in the link above, but I was hoping to stay with the original, if anyone knows where to find them. Thanks.
Re: 1992 High Mount (inside glass) 3rd brake light bulb pn#
Originally Posted by Roorancher
Stay away from LEDs in the CHMSL.
Weird things can happen with your other lighting, and you can get weird warning lights.
Good advice! I wasn’t sure on the Camaro, but having dealt for 25 years with mid-nineties Mercedes~Benz (400E/E420) as daily drivers, I’ve read about the problems guys have had after replacing original lights with LEDs—especially the third brake light! LEDs don’t play well with the CAN bus on those cars. It sounds like this also applies to third-gen cars.
Re: 1992 High Mount (inside glass) 3rd brake light bulb pn#
I really don't see an issue with an LED 3rd brake light. It is on or off via a brake pedal switch. No turn signals or such involved (or a CAN bus).
As a matter of fact I am real close to switching to one myself. Why you ask? Simple, the incandescent bulb runs so hot it has been melting the socket. Replaced the socket once, the second time I soldered the bulb in.
The socket heats up and distorts and the light no longer works. Don't need the hassle of a malfunctioning 3rd brake light...
Re: 1992 High Mount (inside glass) 3rd brake light bulb pn#
There's no CANBus in these cars... no "features from the future" at all... In some of the newer cars, especially "expensive" ones, the "bulb" has a CAN interface in it, so that it can report to the BCM when the light burns out. But not these, not least because CANBus wasn't invented or introduced into cars for another decade or so after these were built.
The usual problems with LEDs are, they draw so little current, that the flashers and any other electrical components that depend on their current consumption, can't tell that they're there; and, their resistance and therefore voltage drop when not fully active is so high, that again, other circuits (cruise control is a classic) that rely on being "grounded" by the bulb when the brake lights are off, can't tell that they're off. That's why lots of cars need "resistors" in the light circuits, special flashers, etc. Cruise control in particular often uses the CHMSL as its brake light "input", and won't realize that the brake lights are off when there's LEDs there (or for that matter, if the regular bulbs are burned out), and therefore the cruise won't work. Don't know if these cars are that way but many are.
Re: 1992 High Mount (inside glass) 3rd brake light bulb pn#
Originally Posted by sofakingdom
There's no CANBus in these cars... no "features from the future" at all... In some of the newer cars, especially "expensive" ones, the "bulb" has a CAN interface in it, so that it can report to the BCM when the light burns out. But not these, not least because CANBus wasn't invented or introduced into cars for another decade or so after these were built.
The usual problems with LEDs are, they draw so little current, that the flashers and any other electrical components that depend on their current consumption, can't tell that they're there; and, their resistance and therefore voltage drop when not fully active is so high, that again, other circuits (cruise control is a classic) that rely on being "grounded" by the bulb when the brake lights are off, can't tell that they're off. That's why lots of cars need "resistors" in the light circuits, special flashers, etc. Cruise control in particular often uses the CHMSL as its brake light "input", and won't realize that the brake lights are off when there's LEDs there (or for that matter, if the regular bulbs are burned out), and therefore the cruise won't work. Don't know if these cars are that way but many are.
Excellent explanation ! Couldn't have explained it better myself.
I tried LEDs in the CHMSL of my 94 TA first, and lost cruise, had an ABS light, and also a "hard" brake pedal. After that happened, there was no way I was putting LEDs in my 91 TA CHMSL either.
Re: 1992 High Mount (inside glass) 3rd brake light bulb pn#
I got a bulb from Super Bright LEDs for this. Works fine and doesn't melt the spot on the lens that usually is burnt looking. Went to their site and easily found listings for all of our bulbs. Haven't checked lately but could be worth a check
Re: 1992 High Mount (inside glass) 3rd brake light bulb pn#
As I posted, the 3rd brake light is on/off via a switch on the brake pedal. No connection to cruise or ABS, which our cars don't have (ABS that is). These aren't 4th gens...
Re: 1992 High Mount (inside glass) 3rd brake light bulb pn#
We have been selling replacement led bulb for the 1991-92 3rd brake lights for a 1-2 years, couple of advantages (less heat and brighter) with no weird issues like what people have on 4th gens. We are using the Diode Dynamics 3156/57 HP48 bulb, they are brighter than most bulbs and have a 3 year warranty. 1991-92 Camaro/Firebird 3rd Brake Light LED Bulb (screamingchicken.com)
09-13-2018, 10:44 AM
In some of the newer cars, especially "expensive" ones, the "bulb" has a CAN interface in it, so that it can report to the BCM when the light burns out. But not these, not least because CANBus wasn't invented or introduced into cars for another decade or so after these were built.
