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1983 Mercury Grandmarquis Brake Indicator Light

Is it normal for the brake indicator light (on the instrument panel.... the same one that comes on when the parking brake is on) to come on when you stomp on the brakes pretty hard?

This happens, even when not moving, such as in park or neutral, of you mash it to the floor, it'll come on, and then go off when I let up. However, when moving (say 35 Mph), and then stomping on them really hard (but nto quite locking up the wheels), it'll come on, but then it will sometimes stay on after letting off the pedal.

This light was on about a week ago, I bled the rear brakes, since I let the resivour for therears get too low and got air in the line, and the light went off. I just happened to notice that the light came on during heavy braking.

Normal or not?

Thanks

Nic

Reply to
Robotnik
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Reply to
Sharon K. Cooke

I checked the reservoirs right after I noticed this issue, they're both still topped off.

Reply to
Robotnik

When the plunger in the proportioning valve is pushed off center it will trigger the brake light to indicate there is something wrong with the brake system.

I would bleed the entire brake system and see if the problem goes away. If not I would check for rusted through brake lines or leaks at the brake calipers or wheel cylinders. If those check out OK then you might just need a new proportioning valve.

Reply to
Dennis Smith

sounds like you are low on brake fluid,,,,, check the master cylinder out and add some fluid....

Reply to
jim

Reply to
Thomas Moats

Reply to
Robotnik

I think the only things that influence that light are the Parking brake, and the proportioning valve.

Within the two years, I think just about everything in the braking system as been re-done, except the brake lines themselves. New master cylinder, power brake booster, new rotors on the front, new calipers on the front, new pads on the front, new cylinders on the rear, turned the drums, new shoes on the rear.

Is it unheard of for a proportioning valve to croak?

Reply to
Robotnik

When the linings are worn out enough the pressure changes allowing the valve that turns on the light to shift. The shifting valve is what turns on the light. Works the same way a leak, which by the way is a nother thing to look for.

Within what two years? Do you mean two years ago? Or has it been longer than two years ago, but in a two year period of time you had the brakes rebuilt? How many miles and what type of driving has this car been put though? Finally, were the parking brake cables replaced? Was brake hardware for the rear linings replaced?

It's not unheard of, but not likely. I would suggest you remove the wheels and do a complete check.

Reply to
Thomas Moats

Reply to
Sharon K. Cooke

Typo..... sorry, LAST two years.

The drums were turned, and shoes replaced, and cylinders were replaced on the rear, just short of a year ago. On the front, the rotors were replaced, pads replaced, calipers repalced, 6 months ago. THe power brake booster was replaced about two years ago, as was the master cyldiner. about 15,000 miles in the last two years, virtually all city driving (maybe 200-300 highway driving). Parking brake cables not replaced. Parking brake pedal has been replaced....about 4 years ago.

Reply to
Robotnik

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