Brake Warning Light

[Musicman]

Hello to all.

While cleaning things up a bit under the hood the other day I noticed that the connection on top of the brake fluid diverter thing (sorry, I don't remember its official name) was not connected. After connecting it and starting the car I noticed that the brake light on the dash stayed on. I know that this is the warning light for the brake system. I also know that the pads and shoes are still in good condition with much life still left in them. I also know that there's no air in the system.

So, what could be causing the brake warning light to stay on? I remember reading somewhere about if the warning sensor on top of the diverter valve is removed there's some sort of rod with a notch in it in there - and if the rod was moved manually to the center of the valve the light would go out. Does this ring any bells for any of you? Also, if the sensor is removed that will allow air into the system, yes?

All thoughts and advice are welcome.

Thanks!

 

[dklawson]

I believe you're referring to the Pressure Differential Warning Valve (PDWV).

From the MOSS web site:
"The pressure differential warning valve will cause the brake warning light to light after almost any work on the brake system such as bleeding the brakes. To reset the switch, remove the wire from the switch, unscrew the switch body and center the small piston in the housing with a piece of stiff wire or similar object. With everything re-assembled, the warning light should be off unless there is a front to rear imbalance in the system."

I hope that helps.

 

[Musicman]

Doug,

Thank you for response. Will unscrewing the switch body allow air into the system, or not?

Thanks.

 

[danmas]

Maybe this will help. https://members.aol.com/danmas6/

Unscrewing the switch will not let air in. Each side of the PDWA is isolated from each other and the switch by the O-rings. However, if your O-rings are bad, you could get leakage. If that's the case, you should repair the unit anyway, and it's pretty simple to do. The hardest part is getting the brake lines off and back on.

 

[Musicman]

Problem fixed!

I did what's recommended at the Moss site and everything is now as it should be.

Thanks to all!

 

[dklawson]

I'm glad it helped.