924Board.org

[Blas]

Hello All,
I appear to have lost my brake lights. Bulbs are good as are the grounds. All other lights work fine. No power to the rear light assembly for the brake sockets. Which fuse is related to the brake lights? This is a 1979 924. I know that some of the fuse panels are different for the earlier cars...
Thanks....

[Benino]

I posted the fuse panel page from the factory manual for the 1977 n/a and the 1980 turbo here:
http://924board.org/viewtopic.php?t=16545&highlight=fun&sid=4502028a46b1cfdf5eb65489e85dff01
I didn't notice the brake lights there though. :-/

You might want to check the brake lights switch. On my 1980 cars its on the brake master cylinder, but I think on your car there is a switch on the brake pedal itself. I've never seen this setup in person though so I can't say exactly where it is or what it looks like.
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1980 Porsche 924 N/A USA
1980 Porsche 924 turbo USA
1987 Porsche 944S USA

[Blas]

There is power to the switch on the master cyclinder...
Anyone with the PET CD have the part number for the switch? Or a replacement part number? I assume it can be replaced without rebleeding the braking system....
I "HAD" a PET CD but I borrowed it to another owner who was fixing his car up to sell. And he included it with the car...go figure....???

[924RACR]

The catalog should be accessible through Porsche's website.

Another option would be to install and wire in a generic brake pedal switch - we did this on my racecar when we switched over to a MC without a pressure switch.
_________________
Vaughan Scott
Webmeister
'79 924 #77 SCCA H Prod racecar
'82 931 Plat. Silver
#25 Hidari Firefly P2 sports prototype

[Blas]

I was hoping there was a NAPA autoparts reference number or something since it's Sunday...
Why are there 2 pressure switches on the master cylinder?

Thanks

[gohim]

1980 and later model year cars use a mechanical brake light switch mounted on the pedal cluster inside of the car.

You could pull the wires for the brake light switch that run from the passenger compartment into the engine compartment (to the brake light switch on the brake master cylinder) back into the passenger compartment. Then simply buy the later model 924/931 brake light switch, mount it on the pedal culster (the mounting hole will already be there), and connect the wires.

You do not have to remove the dead brake light switch from the master cylinder, or bleed the brakes.

[gohim]

1980 and later model year cars use a mechanical brake light switch mounted on the pedal cluster inside of the car.

You could pull the wires for the brake light switch that run from the passenger compartment into the engine compartment (to the brake light switch on the brake master cylinder) back into the passenger compartment. Then simply buy the later model 924/931 brake light switch, mount it on the pedal culster (the mounting hole will already be there), and connect the wires.

You do not have to remove the dead brake light switch from the master cylinder, or bleed the brakes.

[Blas]

Both pressure switches were bad...replaced them both and lights have returned...They must be redundant switches, one may have been out for a while and the other just died lately...

[Smoothie]

Those 2 switches work together to operate the brake warning light. If there's something wrong with the brakes, like a leaking caliper or cylinder, one of the MC switches will move while the other doesn't. This causes current to flow both to the rear brake lights and to the brake warning light in the dash.
When both switches move as they should when brakes are applied, all current is routed to the rear lights and none to the warning light.
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"..it's made in Germany. You know the Germans always make good stuff."


'82 924T, US version, dark green metallic, 5 speed Audi 016G gearbox