Brake Light Switch Test

Jeeps4Brains · Post by **Jeeps4Brains** » Sun Jun 11, 2006 6:15 pm

Is there a way to test the brake light switch while not mounted on the master reservoir?

I hooked a meter up to the leads and took a small drill bit and gently pressed into the fluid hole but nothing happened. Didn’t press really hard as I was not sure if this would screw up a diaphragm or not.

Cacti_Ken · Post by **Cacti_Ken** » Sun Jun 11, 2006 8:09 pm

You might damage the the switch if you force a probe into it. However If I recall it is a small hole. You could connect to your air compressor.
I haven't tested one to see how much pressure it takes to actuate one though.

Jeeps4Brains · Post by **Jeeps4Brains** » Mon Jun 12, 2006 7:34 pm

You are right I hardly put any pressure on the drill bit as I was worried I would puncture the diaphragm.

I talked to someone today that said the same thing you did and suggested I try stepping up air pressure to about 100psi.

Then there is the issue of it being the old switch and who knows what gunk is up inside there.

Jeeps4Brains · Post by **Jeeps4Brains** » Fri Jun 16, 2006 8:21 pm

Here is what I did.

It turns out the cheepo air blow off nozzle I have, if you unscrew the tip, the size and threads are the same as on the brake light pressure switch. So I screwed the switch into the handle of the blow off nozzle. Then I opened the air valve to the line and pressed the valve on the nozzle. I had the ohm meter plugged into the switch. The switch didn’t close until I got to 120 psi. Dose that seem like the correct pressure for the break switch to operate at?

Post by **wesk** » Sun Jun 18, 2006 1:23 pm

That should be close enough. The pressure supplied by your foot would be in the 150 to 300 PSI range.