Brake Light Switch (starting and brake light issue)

ARV90SC

ARV90SC

Registered User
1990 auto supercoupe. My car is equipped with the feature to depress the brakes to start the car. Lately i've been having issues with starting. I almost have to find the sweet spot to get it to start. sometimes i even have to get under the dash and move pivot the switch by hand with the key in the ignition already turned and held to start as I move the brake switch hoping it starts.

I've also noticed my brake lights come on pretty late, almost 3/4 of the way down until the lights come on, so i have 2 questions;

Are the brake lights controlled through this switch as well or is it just for starting? I've seen a connector on the proportioning valve, I thought maybe that was for the brake lights?

And is there a difference in the switch part numbers for ABS vs Non ABS? I was looking on rockauto and they only seemed to have the non ABS switch.
 
D

DOUG H

SCCoA Member
The pressure switch under the floor pan is for the A.R.C. -not brake lights or starting
sounds like your switch may just need adjusting if lights do come on when pushed further.
 
D

DOUG H

SCCoA Member
ARV90SC said:
how do you adjust it?
Click to expand...
Apparently they are not adjustable-I was wrong. A internal spring gets weak over time & they start to show the symptoms you are describing. I think they are all the same, regardless of ABS or non. See what others here think though.
 
ARV90SC

ARV90SC

Registered User
Now that I’ve had time to see how it works I think I know what has happened. The little plate on the switch has bent that’s connected to the spring which activates the micro switch.

Once the master cylinder has reached full travel, I think the pedal can go a little further putting that additional pressure on that little plate, possibly causing it to bend inward. Increasing the gap the pedal has to travel to engage the switch. I have read about guys “adding a shim” to take up this gap, I think I may go this route and report back.

I’m thinking it’s happened over the years after various brake jobs, accumulator failure, abs motor fail, and all the bleeding.
 
D

DOUG H

SCCoA Member
ARV90SC said:
Now that I’ve had time to see how it works I think I know what has happened. The little plate on the switch has bent that’s connected to the spring which activates the micro switch.

Once the master cylinder has reached full travel, I think the pedal can go a little further putting that additional pressure on that little plate, possibly causing it to bend inward. Increasing the gap the pedal has to travel to engage the switch. I have read about guys “adding a shim” to take up this gap, I think I may go this route and report back.

I’m thinking it’s happened over the years after various brake jobs, accumulator failure, abs motor fail, and all the bleeding.
Click to expand...
I've heard about adding a shim, but have never looked to see where/how/etc.
 
3

35th

Registered User
As far as the abs/non abs the switch looks like the non abs switch so I'm thinking they are the same my 97 is non abs and that looks the same to me.
 
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