dashboard brake light
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Intermediate
Joined: May 2010
Posts: 28
Likes: 1
dashboard brake light
78 vet. dashboard brake light operates normaly when putting and taking off emergency brake. however when i step on the brakes the light comes on. checked master cyl and pulled all 4 wheels. no leaks. pads are in good shape. no problems stopping. what am i missing????????
thanks in advance
thanks in advance
Le Mans Master
Joined: Aug 2006
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From: mount holly NC
2025 c3 ('74-'82) of the Year Finalist - Unmodified
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If the light comes on then you have a imbalance between the front and rear brakes.
Pull the pads and take a closer look, you have a bad piston (leaking) or a line leaking somewhere in the system.
Pull the pads and take a closer look, you have a bad piston (leaking) or a line leaking somewhere in the system.
Safety Car
Joined: Sep 2007
Posts: 4,458
Likes: 331
From: Indy Indiana
take it for a drive, starting and stopping several times.. then feel your rotors ( be careful, they may burn your fingers). the coolest one is the one not working and is where your problem is. most likely air in the system. your brake caliper piston seals may leak a little, but they may also let in air. this may be on more than one caliper.
bleed your brakes, pay extra attention to bleeding the cool one, then try the above again.
if it keeps happening then replace the rotor and caliper.
if it continues to happen then you are having bigger issues such as unresolved runout or even a bad master cylinder.
also confirm there are no leaks anywhere in the lines or connections.
bleed your brakes, pay extra attention to bleeding the cool one, then try the above again.
if it keeps happening then replace the rotor and caliper.
if it continues to happen then you are having bigger issues such as unresolved runout or even a bad master cylinder.
also confirm there are no leaks anywhere in the lines or connections.
Last edited by joewill; Oct 8, 2010 at 08:24 AM.
Pro
Joined: Jan 2010
Posts: 518
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From: Panhandle
I'm going with the Brake Distribution Block/Switch
I'm going with the Brake Distribution Block/Switch. According to the Chevrolet Service Manual, it typically takes 100 to 450 psi pressure before allowing full reset (centering) of the piston. Your lite comes on when you step on the brakes and goes out (casually) when you release -- correct?
A properly functioning switch lites up when it senses the failure (taking effort) in the front or rear system and STAYs that way until repaired and reset (taking effort).
Those switches have been around a long time and the seals do fail. Do a search for Posts by Duke94. He is the Guru of the Switch!
TI
A properly functioning switch lites up when it senses the failure (taking effort) in the front or rear system and STAYs that way until repaired and reset (taking effort).
Those switches have been around a long time and the seals do fail. Do a search for Posts by Duke94. He is the Guru of the Switch!
TI
Le Mans Master
Joined: Mar 2001
Posts: 6,640
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From: Ann Arbor Michigan
78 vet. dashboard brake light operates normaly when putting and taking off emergency brake. however when i step on the brakes the light comes on. checked master cyl and pulled all 4 wheels. no leaks. pads are in good shape. no problems stopping. what am i missing????????
thanks in advance
thanks in advance
Gary
Safety Car
Joined: Sep 2007
Posts: 4,458
Likes: 331
From: Indy Indiana
I am currently fighting the same problem.. the switch resets itself when you take your foot off the brake because the pressure equalizes when you do that. therefor my light goes off when I release the brake pedal. plus when I 'pump' up my brakes, the light will go off also, as this causes close to equal pressure in the system.
anytime the light goes on, it is due to the switch sensing unequal pressure between the front and rear systems.. this is almost always caused by air in the system. or secondarily, a bad seal in one of the circuits in the master cylinder. the OP should check for air in the system and most likely the air is in the caliper with the coolest rotor.
now if there is air, how did the air get there?.. most likely a bad seal in the caliper, a bad seal in the master cylinder, empty master cylinder reservoir (sp?), or a bad seal in the distribution block. do the eyeball test on the block and you will know for sure if it is leaking.
anytime the light goes on, it is due to the switch sensing unequal pressure between the front and rear systems.. this is almost always caused by air in the system. or secondarily, a bad seal in one of the circuits in the master cylinder. the OP should check for air in the system and most likely the air is in the caliper with the coolest rotor.
now if there is air, how did the air get there?.. most likely a bad seal in the caliper, a bad seal in the master cylinder, empty master cylinder reservoir (sp?), or a bad seal in the distribution block. do the eyeball test on the block and you will know for sure if it is leaking.
