Brake Light On.....but why?

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San Jose Steve
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Brake Light On.....but why?

Post by San Jose Steve » Fri Nov 02, 2018 1:33 am

Just picked up the car from the mechanic. Had a new master cylinder and booster installed. After dinner I went for a spin on a remote road for some aggressive brake checks. Hammering the brakes at 45mph, the car stops but the wheels do not lock up. In the middle of stopping, the brake lamp lights up. As soon as I back off the brakes it goes out. Non-panic stops to not illuminate the lamp. Parked in my garage, if I really push hard, the light comes on. After a 20 mile drive, and 7-8 hard stops, I don’t find the brake fluid level in the reservoirs diminished at all.

Why would the light come on? Does it mean I have a leak somewhere? I’m stumped....... - Steve
whitehause
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Re: Brake Light On.....but why?

Post by whitehause » Fri Nov 02, 2018 8:31 am

My "guess" would be a little air in the system, or proportioning valve.
spider2081
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Re: Brake Light On.....but why?

Post by spider2081 » Fri Nov 02, 2018 9:12 am

It would be good to know the year and model of your car.
Many of the Spiders have a float switch in the brake fluid reservoir. If the fluid in the reservoir is low it might be causing the light to come on during hard stopping and cornering.
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bartigue
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Re: Brake Light On.....but why?

Post by bartigue » Fri Nov 02, 2018 9:15 am

spider2081 wrote:
Fri Nov 02, 2018 9:12 am
It would be good to know the year and model of your car.
Many of the Spiders have a float switch in the brake fluid reservoir. If the fluid in the reservoir is low it might be causing the light to come on during hard stopping and cornering.
Also check that the wires to the switch are connected; if not one may be hitting the body when you brake and illuminating the light.
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1969, 1969, 1970, 1979, 1980, 1981, 1982, and 1982 124 Spiders
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cripps
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Re: Brake Light On.....but why?

Post by cripps » Fri Nov 02, 2018 11:36 am

It could also be low fluid level in the reservoir. Easy to check, and correct if necessary!
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San Jose Steve
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Re: Brake Light On.....but why?

Post by San Jose Steve » Fri Nov 02, 2018 8:49 pm

Car is a 72 124. Brake fluid reservoirs are full. Didn’t think to check the wire connection at the brake line splitter under the MC. (That’s where sensor lives.) The brake lamp only comes on if I push the pedal really hard. Moderate stoping does not activate the lamp.

Had to leave the car at home and join the Fiat club tour to LA in my Dodge Challenger. Dodge is a Fiat brand right?
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