Brakes: Brake lights come on for no reason

[Warren Webb]

This is a strange one. Yesterday around noon I went out to the 62 Cruiser to go for lunch when I saw the brake lights on. This has happened before. Getting in the car & giving the brake pedal a quick jab & the lights go out. If they had been on from driving the car the day before I'm sure the battery would have been dead but it started right up without any hesitation that would have indicated a low voltage.

The nights have been a bit cool, around the high 50's & around noon when this happened it was around 85 if that may have a bearing on things. It's a 4 wheel drum setup with a stock power booster & a new (2 years ago)65 dual master cylinder for a power drum car. Any thoughts & suggestions would be appreciated.

[JoeHall]

Assuming you have the OEM, pressure switch, residual pressure in the lines, caused by insufficient pedal linkage clearance. Maybe the brake light switch going out, though the usually begin to fail to come on, instead of sticking on. Maybe something wrong with the power assist, putting pressure in the line. If you have an amp gauge instead of idiot light, with key off, you can watch is closely and operate the pedal gently to see how sensitive the light is to pedal pressure in coming on and going off.

A couple of years ago, I bought super sensitive switches, so the lights would come on as soon as I barely press the pedal, instead of when considerable of pressure is the lines. They are available now for older cars so the brakes come on much more quickly, like modern cars. Maybe you accidentally got hold of one of those switches. I had not thought of them as a potential problem, but now guess I'd better start to notice the brake lights when parking and walking away from the car.

[Gunslinger]

I had the same problem some time back in my Avanti and it was the hydraulic brake switch. I ended up installing a mechanical switch...inexpensive and more reliable.

[JoeHall]

I had the same problem some time back in my Avanti and it was the hydraulic brake switch. I ended up installing a mechanical switch...inexpensive and more reliable.

Only thing I'd add, if it is due to residual pressure in the line, the lights sticking on are a SYMPTOM of a another problem. Removing the symptom, would not address said problem, if it exists.

[rockne10]

Could also be as simple as a weak pedal return spring.

[JoeHall]

Could also be as simple as a weak pedal return spring.

Only if it has a mechanical switch. There's no way a bouncing pedal will cause a pressure switch to come on, even the ultra sensitive ones like I installed. If its a mechanical switch, and that is happening, need a stronger spring, and/or adjustment for more pedal travel before it trips the switch.

[jclary]

We've had these discussions before. Brake switch failure. Most of the time, the switches fail to light up. That is...they quit performing their job to turn the lights on. Here, yours is taking the initiative to turn them on when they are not needed.

Since it is a pressure switch, you would think there is no way for this to happen under normal circumstances. I wonder if it can happen from "thermal expansion?" Let's say you park your vehicle, it cools, and, relative to ambient temperature, the system, maintains barometric pressure normal for the altitude in conjunction with temperature. Then...with the warming of the day, and the temperature increases, there is the possibility that a tiny obstruction in the master cylinder vent that prevents it from allowing air to escape (in other words, equalize) "thermal expansion" occurs building enough pressure to activate the switch. An easy check for this is to wait until the switch turns the lights on, and unscrew the cap. I have seen this before, but not on my vehicles.

Last year, I posted a thread on the opposite problem. After replacing a couple of switches on one of my cars using silicone (DOT 5) brake fluid, I tore into the switch to investigate. Since we have lost most pics from threads posted before the server switch, I had to find the old thread and restore the pic. Here's the link to that thread.

http://forum.studebakerdriversclub.c...402#post959402

[Skip Lackie]

I have had the same problem with the brake pressure switch on a LaSalle, which uses a switch similar to Studebaker. I believe they can fail either way: sticking on or sticking off.

[thunderations]

Any fluid other then DOT3 seems to cause premature failure of the pressure switches. I just had one start leaking around the crimp holding the electrical post insulator, but that was with DOT 3 so it was another matter. Had a lifetime warranty, so got another and fixed the problem. Some parts are good to get from local parts stores for that reason, ONLY. I have never had one fail "ON", only off.

[StudeRich]

The MOST likely problem Warren is the Pedal Return Spring on the cross shaft under the dash is weak, this is a very common situation on the Suspended Pedal (Ford) setup.
Exactly as Post #5 and 6 said.

It's gotta be Henry's fault! Lol!

I do not think the Pedal is heavy enough to actuate the Hydraulic Brake Light switch, but it IS possible that it could cause the issue Gary mentioned, pressure build-up from the Bleed hole being covered and the extreme Temp change in the Semi-Desert area. MAYBE!

[studegary]

To me, it sounds like you have insufficent pedal clearance to allow the master cylinder rod to fully retract and have some free play. This is allowing pressure build up in the brake fluid when the ambient temperature rises, causing the brake light switch to activate.

[E. Davis]

Make sure your master cylinder isn't too full and doesn't allow for expansion when the fluid heats up. That's what happened to mine.

[Warren Webb]

The master isn't full to the brim but it may be the return spring. I'm going to lube the pivot with some KROIL & see is that helps. Will let you know.

[SC38DLS]

Being a fairly new Studebaker owner I don't know the different models well enough to know if you have a hill holder but if so & if it has residue buildup it will keep the light on.

[stude dude]

Are you experiencing any brake fade? Do the brakes smell 'hot' after a relatively short drive?

Chris.