TheSamba.com :: View topic

Sat Sep 20, 2008 9:24 am

Has this ever happened to anyone? I just put a new master in my car and now I have no brake lights. All of my fuses are good and the plugs to the master are not damaged. The new master cylinder was a bit different, as it didn't have the check valves that the old one had, so I put it in without the check valves just to see if it would work. Now my brakes work fine, but I have no brake lights. Do those check valves have anything to do with the lights?

Oh yeah, the pan is a 1970, I probably should have mentioned that.

Sat Sep 20, 2008 10:49 am

On AC VWs, brake fluid pressure actuates the stop light switches on the side of the master cylinder. So you either have to re-bleed the system, or unscrew the switches, wet the ends with brake fluid, re-install, and re-bleed. Traditional vehicles have a switch that actuates the brake lights when the brake pedal is pressed.

Sat Sep 20, 2008 11:13 am

^Thanks for the response. I've already done what you're talking about, though. Could the problem have anything to do with those check valves I left out?

Mon Sep 22, 2008 11:27 am

Any other ideas?

Mon Sep 22, 2008 11:38 am

Can we assume that you have checked that the switches themselves are closing electrically?

Max

Mon Sep 22, 2008 12:36 pm

What check valves are you talking about? Are you refering to the brake switches?
Try this first.
1) Turn on your ignition
2) take off one of the brake switched at the master cylinder
3) Make sure it's plugged into the connector
4) Insert a small plastic or wood tip to the hole and push in (one of those spray can extension tubes work great for this)
5) If your switches are working correctly, then the brake lights should come on.

If they don't either you have no current coming to the switches or your switches are bad.

Mon Sep 22, 2008 1:20 pm

Max Welton wrote: Can we assume that you have checked that the switches themselves are closing electrically?

Max

Yeah

Yehan73 wrote: What check valves are you talking about? Are you refering to the brake switches?
Try this first.
1) Turn on your ignition
2) take off one of the brake switched at the master cylinder
3) Make sure it's plugged into the connector
4) Insert a small plastic or wood tip to the hole and push in (one of those spray can extension tubes work great for this)
5) If your switches are working correctly, then the brake lights should come on.

If they don't either you have no current coming to the switches or your switches are bad.

My old master had what looked like check valves. I could be wrong, I'm not familiar with them, really.

But thanks for the tip, I'm going to have to try that.

Mon Sep 22, 2008 3:31 pm

zombie wrote: Max Welton wrote: Can we assume that you have checked that the switches themselves are closing electrically?

Max

Yeah
If the switches work the problem is not hydraulic, it's electrical.

Max

Mon Sep 22, 2008 5:17 pm

Yup, are all the wires back in the right place? Time to go to the bulbs in back and see if they are getting voltage....