Instrument panel brake light

[tetraruby300]

Hey guys,

The instrument panel brake light lit up today on my '85 Civic. Without studying the electrical shematics what sensors trip this light? I know the parking brake does. I also think there's a low fluid level sensor. Does a problem or inbalance in the proportioning valve trip it as well?

Here's the wierd correlation. Car just experienced cold (freezing) overnight temps since I've owned it. The light did go out after driving about 20 minutes.

I know the master cylinder tends to leak (pedal will slowly go to the floor) when it's colder out. I suppose the seals expand in the MC when it's warm. Do you think this condition would cause the light to kick on?

TIA

[avistar]

From what you describe it is most likely the MC fluid reservoir. If it goes down as the pads get thinner the brake level is reduced and the light will go on. If you top up the fluid that should solve the light problem.

However if you have a leaky MC then you have another problem to rectify. Again from the description it sounds like one of the seals inside the MC is starting to go causing the pedal to depress.

Try this. When the car is idleing put foot on the brake. If the pedal slowly starts to depress then it is a seal inside. There are basically two o-rings inside that need to be replaced or a buy a rebuilt if you are more confident with that. You may also be leaking fluid into the booster but then your MC level would be going down more rapidly. Good luck. S

[tetraruby300]

I made some headway. I realized that the fluid level in the MC reservoir has a low level switch. Upon inspection, I have a slow leak from one of my brake cylinders...pisses me off. I just replaced the cylinder about a year and half ago. I don't do much braking either, which gets me. Yeah, the MC has been going south, but it's usually most obvious when it's cold out....suppose I should be doing both. What's with these cars and brakes? I have had more brake problems than I care to share.

[Albert227]

I have a '01 honda accord and just this morning the parking brake light came on when i started driving. It was cold this morning but i didn't have the brake on so i don't know why it would stick. Could it be the brake fluid is low

[avistar]

Yes, re-read my last post. First paragraph. Sometimes the float gets stuck. Stick your finger in the reservoir and move it. See if the light goes off. Add fluid to proper level. JS