Brake light on
Thread Starter
Racer
Joined: Jul 2013
Posts: 423
Likes: 6
Brake light on
Took my 78 out riding yesterday,, it ran great all day.. When we got in to go to another stop the brake warning light came on when I started the car and didn't go off... The brakes were working fine and the master cylinder was full and couldn't see any leaks.. The parking brake was all the way off too.. I went out this morning and took a closer look and couldn't find anything wrong and the light stayed on when I started the car.. Does anyone have any ideas as to what else to look at or check ? Thanks for any help.
Team Owner
Joined: Jul 2006
Posts: 22,197
Likes: 4,180
From: Kannapolis NC
The parking brake light switch is most likely causing it. You can troubleshoot by disconnecting the wire off the distribution block below the master cylinder. If the light stays on, disconnect the wire from the parking brake switch. One of the two should make the light go out and tell you where you need to work.
Thread Starter
Racer
Joined: Jul 2013
Posts: 423
Likes: 6
The parking brake light switch is most likely causing it. You can troubleshoot by disconnecting the wire off the distribution block below the master cylinder. If the light stays on, disconnect the wire from the parking brake switch. One of the two should make the light go out and tell you where you need to work.
Former Vendor
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From: Jeffersonville Indiana 812-288-7103
St. Jude Donor '08-'09-'10-'11-'12-'13-'14-'15
Willcox
Team Owner
Joined: Jul 2006
Posts: 22,197
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From: Kannapolis NC
Yep, you have a leak or air in the system most likely and the light is doing what it's supposed to. I suppose a malfunctioning master cylinder could cause the pressure to vary between front and back, but check the easy stuff first.
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Former Vendor
Joined: Aug 2006
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From: Jeffersonville Indiana 812-288-7103
St. Jude Donor '08-'09-'10-'11-'12-'13-'14-'15
Pumping the pedal is building the required pressure to keep the light off....
So.. other things besides a leak..
Defective master cylinder
Air in the system possibly from a warped rotor.
I'd for sure double check the back of the tires, the calipers have such a bad history of leaking. Then I would bleed the brakes and see if the light goes off when the pedal is pushed. If it does take it for a spin and see if it comes back on. If the light comes back on then I would check the run-out on the rotors or possibly replace the master cylinder.
IMHO,
Willcox
So.. other things besides a leak..
Defective master cylinder
Air in the system possibly from a warped rotor.
I'd for sure double check the back of the tires, the calipers have such a bad history of leaking. Then I would bleed the brakes and see if the light goes off when the pedal is pushed. If it does take it for a spin and see if it comes back on. If the light comes back on then I would check the run-out on the rotors or possibly replace the master cylinder.
IMHO,
Willcox
Team Owner
Joined: Jul 2006
Posts: 22,197
Likes: 4,180
From: Kannapolis NC
My 72 brake light come on under hard braking with the first press of the pedal. If I pumped it a couple of times the light didn't come on. I bled the back brakes and I had some air in the right rear. So far I've driven it 3 times with the light not coming on under any conditions.