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Architecture & Porsche's
Join Date: Jan 2006
Location: Austin, Texas
Posts: 3,189
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Brake lights no worky on '81: anyone experience this??
My brake lights on my track car have stopped working, as I drove home from work one day (wierd).
Bulbs are good (verified) Fuse is good (#10), connections to fuse are clean Contacts to both pressure sensors (under master) are clean & debris/fluid free Both pressure sensors replaced a year ago brakes work  so there's pressure for the sensors (no fluid leaks)Contacts on little brain above fuse panel are clean. Where else should I check?? Pooh... Mark
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Porsche Club Racing National Scrutineer '89 Andial 951 '82 928R '74 911 RSR 3.6 |
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05-19-2008, 08:29 AM
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Network Native
Join Date: Jan 2007
Location: SoCal
Posts: 10,349
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Use one of those hold the hood open things (broom) to hold the brake pedal down and start checking voltages. Could be the classic visually clean, electrically dirty.
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05-19-2008, 08:53 AM
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Registered
Join Date: Feb 2008
Location: El Cajon CA
Posts: 480
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When the brake pressure switches went bad on my '79, I replaced them with some cheap Brazilian imports (Autozone) and then my brake lights would only work when I stepped really HARD on the brakes.
 Picked up some switches at NAPA and been working fine since. Give the pedal a good stomp and see if that makes the brake lights come on. |
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05-19-2008, 09:05 AM
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928-Electrics Guy
Join Date: Jun 2007
Location: Phoenix AZ
Posts: 715
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Do your windshield wipers still work?
Alan
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1994 928 GTS Black/Black Manual |
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05-19-2008, 09:55 AM
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Architecture & Porsche's
Join Date: Jan 2006
Location: Austin, Texas
Posts: 3,189
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I' recently tossed the broom stick since my buddy & I bought 14 hood/trunk shocks to please the cars in our corral.
I've cleaned all the components, still no brake lights. We replaced the switches a year ago and the brakes have been working fine: I suppose that with a probe & a wiring diagram, I could complete the necessary circuits & see if I can make the brake lights work: this would pinpoint the switch(es) as being bad. I have not used the wipers in 2 weeks: will do that tonight (share the same circuit I assume?) Mark
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Porsche Club Racing National Scrutineer '89 Andial 951 '82 928R '74 911 RSR 3.6 |
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05-19-2008, 12:49 PM
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Registered
Join Date: May 2008
Posts: 104
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try replacing the fuse just a thought
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06-18-2008, 05:03 PM
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928-Electrics Guy
Join Date: Jun 2007
Location: Phoenix AZ
Posts: 715
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Well...
Quote:
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1994 928 GTS Black/Black Manual |
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06-18-2008, 08:40 PM
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928: Serial Enabler
Join Date: Sep 2007
Location: Elkhart, Indiana
Posts: 2,929
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Sounds like bulb control unit failure on the reed-switch operated little brain. Stoplight power is therefore not passing through it. Bypass.
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84,85,86 928 cars |
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06-19-2008, 01:45 AM
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Registered
Join Date: Jan 2007
Location: Atlanta
Posts: 305
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Being a track car is a good opportunity to dispose of all the wierd stuff like pressure switches and control units and wire the lights directly from a pedal switch. The only downside is that you don't get to use Alan's expertise to trouble shoot
If you do that be sure to tap power from the switched side of your master power switch (if you use one), that's a common mistake among track cars, I've seen inspectors ask to push the brake pedal with the switch off to look for that.
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Mike S. 79 928 Racer 427ci 32v 640WHP |
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06-19-2008, 03:01 AM
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Architecture & Porsche's
Join Date: Jan 2006
Location: Austin, Texas
Posts: 3,189
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I have brake lights now: one of the pressure swithes was bad, but now since the switches are of different mfrs and ages, my exclamation light flashes continuously: I need to change out the other.
Mark
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Porsche Club Racing National Scrutineer '89 Andial 951 '82 928R '74 911 RSR 3.6 |
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06-19-2008, 08:25 AM
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