Sub zero climate P brake anomaly

[NikFu S.]

Whenever the temp drops to around zero or below and I go to start my car, the P brake light stays on. Doesn't matter if the brake was on or not.
It's done this 3 days in a row. 2 days the brake was on, today it was not but the light still came on and stayed on until I got to destination and it sat for a few hours.
I tested the brake while driving and it seems to be moving freely.



Other than that and near-solidified PS fluid this car kicks Alaska's ass.

[Crazy_pilot]

How sensitive is the switch? It might be that although the parking brake is dissengaged, due to the cold something doesn't fully move to it's resting position (by a tiny amount) and that's enough to keep the switch tripped and the light on. So even though the brake isn't being used it's not quite fully dissengaged. Does my rambling make any sense?

[Hocrest]

Check the rubber diaphragm inside the lid of your brake fluid reservoir.

[NikFu S.]

Originally Posted by Crazy_pilot

How sensitive is the switch? It might be that although the parking brake is dissengaged, due to the cold something doesn't fully move to it's resting position (by a tiny amount) and that's enough to keep the switch tripped and the light on. So even though the brake isn't being used it's not quite fully dissengaged. Does my rambling make any sense?

That's what I thought originally but I parked yesterday with the brake and light off. It just seemed to come on randomly.

Originally Posted by Hocrest

Check the rubber diaphragm inside the lid of your brake fluid reservoir.

Will do. I have to go fish out my block heater plug in a minute anways..

Some nimrod cut off the end of the little plug thingy way back before I got the car. :/

[Crazy_pilot]

My Taurus used to do the same thing, the light would stay on after the brake was off. Now the light just doesn't work at all. So the last time I traded cars with someone for a quick drive he didn't know the parking brake was on (it's one of the foot brake types). I honked him off the side of the road when I saw the smoke trailing off my car's back wheels. And then the happy clicking sound of overheated brakes cooling. Ya...I leave a note on the steering wheel now when someone else drives the car.

[NikFu S.]

Every single person that has gotten behind my wheel has tried to move it without disengaging the P brake. Even me a few times.

Most people just don't use them.

[Crazy_pilot]

Nope, and I cringe every time I see a car stop on a hill and then lurch horribly as the trans takes all the abuse...And then the nice loud BANG when they yank it into gear. And when they eventually try to use the P brake that hasn't been worked in years and it...well...doesn't work. Silly people.

[AlcyoneDaze]

Hill parking is the only time I use the parking brake. I was informed that failure to do so would wear down and eventually bust the parking pin, if that is the correct term

[Crazy_pilot]

Indeed it will, and then you'll see your car rolling down the hill until something stops it.

P.S.: The XB-70 was such an awesome design. Too bad it never went anywhere.

[Manarius]

I think it's amazing though how someone parks on a hill then puts on the Parking Brake after they put the car in park. That completely defeats the purpose of the Parking brake (because its purpose is to take the stress off the transmission).

In regard to this situation, I think Hocrest hit the nail on the head.

[svxcess]

Originally Posted by Hocrest

Check the rubber diaphragm inside the lid of your brake fluid reservoir.

If it is extended, it should be pushed completely back up into the cap.
.

[newsvx]

This has been implied, but I think the "parking / e-brake light on the dash also serves the "low fluid" indicator for the brakes master cylinder. If the fluid is "low" the light will come on ..... Check your fluid level in the master cylinder. BTW, the lack of brake pad thickness will also cause the ligh to come on due to the lack of pad thickness will lower the brake fluid level. This happened to me at the track.......

Harry

[dwd1985]

With all of the recent snow and cold weather we have been having, I had the same situation. I did the search on here, and every thread said to just open the cap and then re-tighten it. Well that did work to shut iot off each time, but invariably, the next time I went to start it, the light would be back on. I checked the fluid level, and it was halfway between maximum and minimum. But I added some fluid anyways, and the light hasnt come back. I think in cold weather, it just needs more fluid to disengage the pin or whatever.

[newsvx]

Originally Posted by dwd1985

With all of the recent snow and cold weather we have been having, I had the same situation. I did the search on here, and every thread said to just open the cap and then re-tighten it. Well that did work to shut iot off each time, but invariably, the next time I went to start it, the light would be back on. I checked the fluid level, and it was halfway between maximum and minimum. But I added some fluid anyways, and the light hasnt come back. I think in cold weather, it just needs more fluid to disengage the pin or whatever.

Extreme cold weather might be reducing the level of the fluid because of less volume due to the cold fluid. 1/2 level will caue the light to come on.
Harry

[NikFu S.]

I don't know why cold brake fluid wasn't one of the first things to pop into my head. I guess I never think about it because my brake system never needs servicing like everything else has.