sulu911

Brake lights on my 997c4s dont work. No current warning. Just replaced the water pump and indy shop actually saw the issue. The Brake switch was replaced but did not solve the problem. They don't have the Porsche computer to check, but the durametric says something about it going to the ABS. I have no ABS code either. ????

Macster

Only time brakes lights failed to work was a bad switch. But the switch was replaced... It could be bad out of the box...

Let's see... I sort of kind of remember hearing from the techs sometimes a burned out bulb can cause a problem with both sides. If not a burned out bulb then a bad light bulb socket or circuit. Maybe water has leaked in and caused some corrosion to start?

You'll have to remove the light bulb carriers and check the things for any signs of water, corrosion or anything amiss.

Also, check the fuses. The brake lights might be on a fused circuit by themselves or with some other electrical system that also doesn't work you just don't know it yet. (The fuse in the spoiler circuit of my Turbo also is the fuse for the electric engine compartment lid latch release.)

sulu911

The shop checked all the bulbs and sockets, but i will double check. Thanks for that info. Blower fan is not working either, but this has been a problem for over 4 months or so. Also, last week the PSM light came on and went off after restart, this happened about 4-5 times during a 7-9 day period.

Macster

Starting to read like electrical gremlins.

What is the history of the car?

Any chance mice are afoot?

What about water in the cabin, or doors even? Water drains can get plugged up and back up water when it rains or you wash the car. Door seals can leak and allow water to collect in the doors. Generally this manifests door/window electrical gremlins but who knows?

Other electrical problems can be a weak battery or alternator.

Yet another possible cause is the ground connection between the battery and the car can develop corrosion. I've been advised to just take a wrench and loosen the fastener a bit then retighten which scrapes away the surface corrosion.

sulu911

No known water issues. Funny thing is when I looked at the fuse diagram, rear fog, tail lights and brake lights on on the same fuse. Rear fog and taillights work just fine so it has to be something with the brake pedal on?

Dadio

Remove the plug from the brake switch and short the wires. If the brake lights come on the switch is the problem. If the backup and running lights work it's not the harness which points to the switch again. If they don't light up the problem is somewhere in the wiring harness or harnesses.

sulu911

Thanks I'll try that

sulu911

Took It to the dealer today. Turned out to be the break light switch, the one Indy shop put in must have been bad. Also for reference PSM light was coming on intermittently, brake light switch has solved the problem for now.

Dadio

Now you need to find a new indy. Testing a switch takes about 10 seconds with even a cheap VOM. Don't think I'd want the guy to replace my clutch if a simple on-off switch poses an insurmountable challenge.

TommyV44

That's why I go to the dealer

Tom