Brake Light and Vaccum Conversion

[whiteregal6]

Brake light is perpetually on now that the Powermaster is unplugged and out of the car. Installed vaccum system, but the light is still there. How do you make it stay off? Thanks.

 

[unix_punk]

My car was already converted to vac when i bought it, but are you sure that you just dont have low pressure or air in the brake lines? Have you bled the system since you've done the swap?

 

[whiteregal6]

Yes, I bled the system right after the swap. I was thinking that the brake light being constantly on was a result of the Powermaster no longer being plugged in, but I could be wrong (probably).

 

[zeus87gn]

Yes, I bled the system right after the swap. I was thinking that the brake light being constantly on was a result of the Powermaster no longer being plugged in, but I could be wrong (probably).

Define wrong. j/k

There are 3 items that make that light work.
If you had no other problems with this light prior to converting, you need to check a few things.

1 - The P/M pressure switch grounds a circuit that powers the light. The wiring that connected to the pressure switch may be grounding out. Find these wires and isolate them. You may even want to trace them throughout to be sure the aren't grounding out somewhere else.

2 - Check your wire(s) on your parking brake. It does the same as the pressure switch so be sure they are in good order and not grounding out somewhere under the dash.

3 - The proportioning valve has a switch in it that operates this light as well. I have heard that you are supposed to set this switch when you pump bleed, then reset it afterwards. I vacuum bleed so I don't have to mess with it. If you pump bled you new vacuum system and didn't mess with this, you may want to investigate.

HTH,
Z

 

[unix_punk]

+1, I didnt know about that button on the proportioning valve when I first bled mine, I could see that possibly causing the light, however on mine it did not.

 

[POWERBRAKEBOB]

Hydroboost Vs Vacuum Vs Powermaster

Pull the wire off of the prop valve, If the light is still on, then it is the P/m wiring. You could pull the fuse/relay for the P/m to remove the power going in to the light.

 

[zeus87gn]

No. That fuse will only power the motor down.
It is not connected to the dash light circuit.

http://www.gnttype.org/techarea/images/PwrMstr.gif

I do agree that it may be in the wiring harness tho.