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I'm new to the forum, but I marvel at the amount of information and troubleshooting that goes on here. I'm hoping someone can help me. Proud owner of a 1990 C4 black/black with only 24,000 miles on it. Everything works - except...the center high mounted brake light will not illuminate - all other brake lights work.
I believe the problem has to be with the switch located by the brake pedal. My problem is getting to the switch to realign or replace it. I've scoured the internet to find videos, photos etc. of how to remove the knee bolster, but I can't find a diagram that shows where all of the screws/bolts are located.
Before I go too far taking things apart:
1. Does anyone know of a diagram showing where the fasteners are located?
2. How is the plastic shield fastened to the front of the footwell?
3. Do you remove just the plastic piece or does the carpet under the dash go with it?
It is really cramped quarters under there, if there is a way to get
at the brake switch from the slot cut in the plastic, I'm interested!
I've got a '93, so I'm not experienced with your year, but I would think that if the other lights are working when you brake, it would imply the switch is functioning. Maybe someone out there can get you a diagram of that circuit.
Nice car! Dont remember if the 90 has the newer interior but there are two big bolts kinda buried in the carpeting on my 85 that you have to remove as well as a couple of obvious screws around the hood pull and the diagnostic port.
You can check for power when the brake is applied at the ABS module, if when the brake pedal is depressed and there's power to the light blue wire then there's power to the CHMSL. If there's not then the CHMSL aspect of the SLS which also activates the ABS is bad and it certainly could be the SLS. The SLS is a single switch but has dual purpose, the rear lamps are fed from the switch through the directional signal switch side of it and the ABS and the CHMSL from the other aspect of it.
I wouldn't remove the hush panel until I had confirmed I didn't have power to the light blue wire at the ABS module. You need to tear apart nothing to check that.
You can check for power when the brake is applied at the ABS module, if when the brake pedal is depressed and there's power to the light blue wire then there's power to the CHMSL. If there's not then the CHMSL aspect of the SLS which also activates the ABS is bad and it certainly could be the SLS. The SLS is a single switch but has dual purpose, the rear lamps are fed from the switch through the directional signal switch side of it and the ABS and the CHMSL from the other aspect of it.
I wouldn't remove the hush panel until I had confirmed I didn't have power to the light blue wire at the ABS module. You need to tear apart nothing to check that.
My 95 base coupe had the same problem, but as jimg's 93 pointed out, it is likely not the switch. I would suspect the lamp in the high mounted fixture itself. That was my fix.
Kelly
08-19-2014, 10:51 PM
C4 Driver's Knee/Hush Panel Removal HELP
