CHMSL info

[rush91]

I noticed yesterday, that my CHMSL brake light isn't coming on. I had the far right bulb go out in January, but kinda forgot about it. Then yesterday I noticed it's not coming on at all. The four lower brake lights are fine......Last night I searched and searched the FSM and couldn't find anything? Anyone know off hand what section I need to be looking in???? I was looking for the brake switch, which I'm sure is the issue. ( i hope )

Electrical stuff is NOT my strong suit, does the FSMs have the wiring diagram so I can track this down? From all the threads I searched on here, it seems the brake switch is a very common issue....

[Mystic ZR-1]

Bet it's the brake lite switch under the dash. Common C4 problem.
Hint: If your over 5 feet tall, take 10 minutes and
remove the driver's seat, 4 bolts and a few elec connectors... makes it
a lot easier to work under the dash.
Good opportunity to clean under the seat and ya might even
find some loose change!

[KPW]

8A-110-0 and 8A-110-1 give the wiring diagrams for the stop lamps and brake switch.

[rush91]

8A-110-0 and 8A-110-1 give the wiring diagrams for the stop lamps and brake switch.

Thank you sir!!

[rush91]

Bet it's the brake lite switch under the dash. Common C4 problem.
Hint: If your over 5 feet tall, take 10 minutes and
remove the driver's seat... makes it a lot easier to work under the dash.


I have learned that lesson the hard way.....wrenched back muscles!

[Z51JEFF]

I've replaced mine several times and it's not too bad. Remove the lower seat cushion,black panel and the switch isn't hard to locate. Be ready to plug in the new switch,with the switch the lights will be energized.

[WVZR-1]

If you have power to the ABS module in the car "BLUE WIRE" when you apply brakes your problem is NOT the SLS. Much easier to check this wire first rather than going up in under the dash to start. On 8A-110 you'll see the "splice" where it has an arrow directing towards the ABS. Very easy check.

** You're not looking for the "splice" - you check it at the ABS module. I mentioned the "splice" only because it's referenced in the FSM.

[rush91]

If you have power to the ABS module in the car "BLUE WIRE" when you apply brakes your problem is NOT the SLS. Much easier to check this wire first rather than going up in under the dash to start. On 8A-110 you'll see the "splice" where it has an arrow directing towards the ABS. Very easy check.

** You're not looking for the "splice" - you check it at the ABS module. I mentioned the "splice" only because it's referenced in the FSM.

Well I found the section in the FSM that has the diagrams. But it might as well wrote in Chinese, I just don't understand electrical stuff. I had no idea I had to remove the carpet piece under the steering wheel to get to anything. Drove out to the car last night, but forgot a flashlight. So couldn't see a damn thing......It looks as though there are about 8 screws I need to take out to remove the hush panel. But hey I'm learning as I go.

So check the ABS module 1ST? Where is that located?

[WVZR-1]

So check the ABS module 1ST? Where is that located?

Left storage compartment behind the driver seat.

See 8A-44 for the wiring and you'll see LT BLU @ C400. See 8A-201-16 for the compartment specifics. Familiarize yourself with the 8A section of the FSM. It is "your friend"!!!!

[rush91]

Left storage compartment behind the driver seat.

See 8A-44 for the wiring and you'll see LT BLU @ C400. See 8A-201-16 for the compartment specifics. Familiarize yourself with the 8A section of the FSM. It is "your friend"!!!!

I will check that tonight....what am I looking for? If my other brake lights are working, how would it be the ABS? I'm sure the two go hand in hand, but does the wiring run from the ABS to the brake switch?

[Z51JEFF]

I will check that tonight....what am I looking for? If my other brake lights are working, how would it be the ABS? I'm sure the two go hand in hand, but does the wiring run from the ABS to the brake switch?

You're not checking the ABS you're checking power to the 3rd brake light which is the light blue wire,I think that's what your doing. I just replaced the switch about 6 months ago and already forgot the process to get to it but it's not that bad. I think only the black panel comes off,don't forget the round speed nut type fastener at the very back of the panel by the firewall.

[Mystic ZR-1]

Cut to the chase...
Forget all the ABS stuff.
Dollars to donuts it's the switch.
It has 2 sets of contacts, one for
the brake lites the other for the CHMSL.
Some people just jumper the 2 circuits together
on the brake lite part of the switch...

[rush91]

You're not checking the ABS you're checking power to the 3rd brake light which is the light blue wire,I think that's what your doing. I just replaced the switch about 6 months ago and already forgot the process to get to it but it's not that bad. I think only the black panel comes off,don't forget the round speed nut type fastener at the very back of the panel by the firewall.


Speed nuts.....I hate speed nuts. Replace the front hood emblem not to long ago and learned about speed nuts.

[rush91]

Cut to the chase...
Forget all the ABS stuff.
Dollars to donuts it's the switch.
It has 2 sets of contacts, one for
the brake lites the other for the CHMSL.
Some people just jumper the 2 circuits together
on the brake lite part of the switch...


That's where i was going to start last night, but couldn't figure out how to get the panel off. And ran out of light. I wanted to check the switch because I heard the connection comes loose or after 25 years it just went bye bye. Probably be good to replace it anyways....Thanks guys for the info and patience.

[rush91]

Fellas I'm at a total loss.....I got hush panel halfway off. I pulled the wire for foot well light, but couldn't get panel all way out. So I moved it to the side, could get access to the brake switch. But I have NEVER seen so much duct tape......its crazy. I don't know how to even go about removing the switch.....do you remove the wires going to it 1st? Is it held in by screws or how? This is becoming a big pain in the ***, I'm totally stuck and frustrated

[Z51JEFF]

The switch just pulls out of the bracket,once you get it out you will see how it's held in place. Putting it back in just push it in the hole.