Blinking Parking Brake Light. Options

[Olympic 914]

Out running errands and when leaving I noticed the brake light blinking. I do use the parking brake a lot. so I pulled it on and off a couple times, no change. The brakes feel normal. Stopped for gas and checked the fluid reservoir, its at the proper level.

Then driving home, after a couple miles the light went off. (?)

When I got home it was back on again.


I am thinking maybe a wonky parking brake switch. But will check the switch on the master also

Is the parking brake switch a Normal Open or Normal Closed?

Anyone else have this happen ? Or know of something else I should check....

[Superhawk996]

The master cylinder switch is triggered by a pressure differential between the hydraulic circuits.

Differential pressure allowed a small piston to move one way or another based on which side of the piston had higher pressure on it. That movement triggers the electrical switch.

If triggers again after the reset, I would take that warning seriously and would investigate what is causing it to trigger. Usually that is a sign of a failing master cylinder. It can also indicate that there is external leakage somewhere but that is not as common of a failure as a an internally leaking master cylinder due to worn seals or corrosion of the piston bore.

[bkrantz]

The master cylinder switch is triggered by a pressure differential between the hydraulic circuits.

Differential pressure allowed a small piston to move one way or another based on which side of the piston had higher pressure on it. That movement triggers the electrical switch.

If triggers again after the reset, I would take that warning seriously and would investigate what is causing it to trigger. Usually that is a sign of a failing master cylinder. It can also indicate that there is external leakage somewhere but that is not as common of a failure as a an internally leaking master cylinder due to worn seals or corrosion of the piston bore.

Yup. It could mean that you have no/little front or rear braking.