Parking Brake Switch Sticking - Toyota Nation Forum : Toyota Car and Truck Forums

cipher93 · 10-16-2011, 10:09 PM

On my 93, the switch that tells you if the parking brake is up is sticking/making bad contact and intermittently making the light come on. It's worse than it's cold. I've checked out the brakes and they're good, as is the fluid level so I'm pretty sure it's the switch. The switch is pressed down when the brake lever is down. So I was thinking when the switch is up it's opening the circuit, triggering the light? I was wondering if there was a way to take it apart?

I've taken the console off to spray cleaner in it and it looks sealed but I was just wondering if there might be a way to fix it. If I can fix it, would I be alright just jumping the contacts to make the light go out? It would not be the first choice but I've had no luck finding a sensor at my junkyard and I'm not going to pay my dealer an arm and a leg for simple DPST pushbutton switch.

cipher93 · 10-17-2011, 05:40 PM

On looking at the switch, it can't easily be jumped... but it doesn't matter. Had it out on the drive to get another, and the light went out

Brakes check good, fluid is fine... guessing it's just a short somewhere causing havoc, but since cleaning and bending out the switch contacts it hasn't some on.

sequoiasoon · 10-19-2011, 04:06 AM

Take picture of said switch and post. Might still have mine you can have.

I had a problem way back with old/dirty brake fluid. So much sediment on bottom of master cylinder would block the sensor and light would come on saying low fluid, worse in turns. The sensor is actually a photo eye. I emptied reservoir, removed the screw, removed the tank cleaned it out. Put it all back together with new fluid and bled (flushed) brakes. Problem gone.

cipher93 · 10-19-2011, 04:17 PM

I was thinking about the switch in the reservoir. I did have the brake fluid changed out when I had new brake lines done last year too, so maybe it stirred up something. The other thing I considered is that switch going bad. Guess there is no way to swap that sensor out without taking apart the cylinder and having to put in new fluid? I appreciate the offer on the switch, but unfortunately I've put the console back together after testing the switch and finding it good.

pdq · 10-19-2011, 06:24 PM

You can disconnect the electrical plug from the fluid reservoir sensor. If your light goes away, you either need to put more fluid in there, or the float has gotten stuck down.

sequoiasoon · 10-19-2011, 11:58 PM

The sensor (photo eye) actually slides out separate. It's in a self contained well that is not in contact with the fluid. The sludge accumulates on bottom of reservoir above that area making it think that the float is low. You could probably stir it around and suction it, refill, repeat a couple times to replace it.

I just pulled the reservoir (it just sits in O-rings held by the one screw) and sprayed it out with brake cleaner. I let it dry good, used air compressor to circulate better and then just held the holes and sloshed some fresh fluid around then drained before putting it back on. Sounds a little complicated but took about 20 minutes total. iirc when I bled out afterwards, I got no air anyway as the master cylinder itself always had fluid in it. But I used the opportunity to flush the whole system anyway.

cipher93 · 10-20-2011, 07:28 PM

Solved it... it involved the switch on the brake reservoir. The wiring harness had gotten dirt/debris/moisture in the contacts on the connector, causing issues. Probably also explains why it got worse after a really cold night and tended to stay out the longer I drove. Cleaned it out with contact cleaner and it hasn't come back on since. what a relief too, as in the next day or two I'm parting with the car

Thanks for the help guys.