Brake Warning Lamp Sensors? [Archive] - Forum


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08-08-2012, 11:53 AM
Hey everyone;

So this is the summer of repairs for my car and there are some bugs I'm trying to work out. The problem I have right now is the Brake/Parking Brake warning lamp is coming on every time I use the car. It doesn't come on right away, but at different times. Once it comes on, it stays on until I stop and start the car again.

About a month ago, one of my rear brake lines sprung a leak. While fixing it the other rear line started leaking at a rusty section. Since I was away working and in the middle of nowhere, the fix ended up being splicing one brake pipe with a furled end in using a connector and splicing a non-furled pipe in for the other side using two connectors. Had to replace the rear driver side caliper because the bleeder screw was too far gone. Everything will be fixed properly next week.

A while later while getting other work done, I noticed one of the connectors had half a drop of fluid hanging on it. So we tightened it up. Checked it again later and was still wet but not dripping. So I assume it may be leaking ever so slightly. The brakes feel spongy but work well. I'm hearing a noise though that sounds like a warped rotor rubbing against the brakes. Applying the brakes seems to stop/drown out the noise. I assume it's the pads touching the rotor in spots. I've had problems with sticky calipers too though.

The reservoir ran dry on fluid when the original leak occurred. Since it's been fixed, the reservoir has been right on the full mark. Some searching told me the warning lamp only comes on in two conditions: low fluid and the parking brake is engaged. I tested the parking brake and the lamp comes on and goes out properly. So I assume it's something to do with the reservoir. Perhaps the float is stuck? Bad sensor?

Is there any other reason the lamp would come on?

08-08-2012, 03:28 PM
Well, for starters you probably have air in your master cylinder. You aren't supposed to let the fluid reservoir get below 1/4 full. If it goes empty you are supposed to bench bleed the master cylinder. That could be the cause of your spongy pedal, and the brake light coming on as well. Other things could be contributing to it too though. I'd get the caliper replaced and the lines fixed properly, make everything as it should be, then get the system bled properly. If you don't know how to bench bleed a MC, taken in and get it done.

08-08-2012, 05:45 PM
Letting the reservoir run dry can damage the piston seals in the MC as well and it might be bypassing some fluid now. If the pedal is still spongy after a bench bleed I'd replace the MC.

08-08-2012, 06:17 PM
Nobody even mentioned bleeding the MC. The line busted a little ways from home and it was empty by the time I got home. Didn't take long. We did replace one rear caliper but the other one was fine. We bled all four wheels.

I checked the float today and it was fine. Doesn't seem to float very well though. Tap it and it drops quickly.

So I guess the next step after fixing the lines properly is to take it in and bleed the MC. After that, like a few days later, the rocker panels are getting done and the paint is being touched up. The rocker panels are pretty much gone altogether. I've never seen metal deteriorate so fast. I work a few months out of the year on a small island with very salty air. When there are strong winds, the car is literally covered in salt spray the next morning. Takes quite a bit of washer fluid to get it off the window. We're also touching up the paint, again. The slight rust spot by the gas tank has developed a small soft spot the size of your pinky finger. Every fender has a rust spot and the paint we put on before is pretty much gone now.

Oh yeah, and on top of all that, some of the stud bolts in both exhaust manifolds have broken off flush with the motor. They were there one time, and now they're gone. Looking at $600 in labor to replace them. I love the car but it's quite costly in maintenance when you don't have your own garage.

Either way, you guys have always been a great help. Thanks a bunch :)