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zombie
Samba Member
Joined: June 17, 2004
Posts: 1177
Location: Pothole City, CT
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 Posted: Sat Sep 20, 2008 9:24 am Post subject: New master cylinder = no brake lights? |
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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.
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I run two fuel filters in my engine bay. |
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Cusser
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Joined: October 02, 2006
Posts: 33086
Location: Hot Arizona
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| Posted: Sat Sep 20, 2008 10:49 am Post subject: |
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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.
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1970 VW (owned since 1972) and 1971 VW Convertible (owned since 1976), second owner of each. The '71 now has the 1835 engine, swapped from the '70. Second owner of each. 1988 Mazda B2200 truck, 1998 Frontier, 2014 Yukon, 2004 Frontier King Cab. All manual transmission except for the Yukon. http://www.thesamba.com/vw/forum/album_page.php?pic_id=335294 http://www.thesamba.com/vw/forum/album_page.php?pic_id=335297 |
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zombie
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Joined: June 17, 2004
Posts: 1177
Location: Pothole City, CT
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| Posted: Sat Sep 20, 2008 11:13 am Post subject: |
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^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?
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zombie
Samba Member
Joined: June 17, 2004
Posts: 1177
Location: Pothole City, CT
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| Posted: Mon Sep 22, 2008 11:27 am Post subject: |
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Any other ideas?
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I run two fuel filters in my engine bay. |
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Max Welton
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Joined: May 19, 2003
Posts: 11045
Location: Black Forest, CO
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Yehan73
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Joined: June 18, 2008
Posts: 649
Location: Fort Collins, CO
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| Posted: Mon Sep 22, 2008 12:36 pm Post subject: |
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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. |
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zombie
Samba Member
Joined: June 17, 2004
Posts: 1177
Location: Pothole City, CT
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| Posted: Mon Sep 22, 2008 1:20 pm Post subject: |
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| 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.
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I run two fuel filters in my engine bay. |
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Max Welton
Samba Member
Joined: May 19, 2003
Posts: 11045
Location: Black Forest, CO
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jugglerkevin
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Joined: January 15, 2007
Posts: 118
Location: Kokomo, IN
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| Posted: Mon Sep 22, 2008 5:17 pm Post subject: |
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| 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.... |
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