por917

Hey guys, I've been looking through the various threads about Stop lamp warning issues. I have a couple avenues I'm going to look into tomorrow. That being said my exact problem has not been addressed that I could find. The issue I have is every time I press my brake peddle the stop lamp warning comes on with the ! I have to reset every time I touch the brakes. The other thing to throw in there is the normal sequence of when you start the car and all the warnings on the dash come on. The stop lamp should come on and extinguish when I depress the brakes. This is no longer coming on during start up. But as soon as I touch the brakes the warning comes on and triggers the (!).

I was also having the tail lamp warning coming on when I would turn on the lights. So I figured that I was having a problem with possibly aging lamps. I have replaced all tail lamps and side markers with the correct voltage bulbs. The tail lamp problem went away but the stop lamp warning is lingering.

After looking in the forums the two directions that I'm going to look into are the 2 brake switches under the master and if I have to the ground point in the RR quarter panel. Although I was only there just a few years ago and cleaned up that area really well.

Is there a way to test the lamp control unit that is located in the pass side above the fuse Relay panel?

Any other suggestions?

soontobered84

When you last replaced your brake light bulbs, did you replace both at the same time? The car measures one side vs. the other side. If one side of the car uses different amount of amps(?), it will kick on that warning. Also, check your marker bulbs on each side.

davek9

I'm assuming you meant Wattage not Voltage, as they are all 12v, it's the wattage that matters, did you clean the connections and unplug the sockets as corrosion will also cause this?

GlenL

For debugging only: if you disconnect one of the connectors on the bottom of the master the warning light will not come on due to a of a switch there. If you've left a bad switch connected up, the brake light will just not come on. Check that before proceeding.

Also, the brake switches come in several levels of cost and quality. These parts went into millions of cars so are made worldwide for cheap. Get a reputable brand and pay the $10+ apiece.

jpitman2

Try the disconnecting of the switches one at a time to see what happens with the warning light. Note that getting the connector back on can be a challenge. My warning used to come on for BRK ?? to do with one circuit failing. Pulled one switch and its wiring was twisted up very tightly, fixed that, problem seemed to go away. The switches are cheap Audi/VW items. I swapped one - remove reservoir cap, cover with gladwrap, refit cap - minimizes fluid loss; remove switch (24mm), fit new one CAREFULLY - too tight can crack m/cyl. Remove gladwrap, kick pedal around, you shouldnt need to do any bleeding.
OR, it could be a sign that one circuit has a problem!
jp 83 Euro S AT 57k

por917

Well after further troubleshooting I went ahead and found a replacement Lamp control module. Installed yesterday and whaa laaa problem fixed! Thanks for the information guys. This forum is indispensable if you are a 928 owner. I appreciate the wealth of help you guys provide!

Rich

928Collector

I'm having TAIL LIGHT and STOP LAMP warning lights come on.
Also when I put the car in reverse, the reverse lights do not come on. All other lights work.
I saw a forum discussion where a 928 owner replaced their Lamp Control Module and his issues were resolved.
Is this where the lamp control module is located?
I'm thinking of removing mine for a cleaning/Deoxit
Any advice/heads up and/or instructions as I don't want to create more electrical issues/complications around the fuse box.

Lamp Control Module removal?

Mrmerlin

yes thats the LCM
NOTE the bottom of the blower box can leak and then water will damage the electrical components.

If you find corroded fuses, relays or other electrical connections are corroded,
then water intrusion has happened .

IF so then removal of the blower motor then the blower box should be performed so the putty seal can be replaced

928Collector

Thanks.
Is it an easy/mid level fix to remove the Lamp Control Module?
I'd like to inspect and Deoxit for starters.
But i dont want to get in over my skil/experience level and create a bigger electrical problem.
Please advise

coachsteve

Right after a heavy rain both TAIL LIGHT and STOP LAMP warnings came on, and both stop lamps stopped working, while tail light is still working. Seems to be the exact blower box leak issue that you're describing. Can you point – where do I locate the blower box? Thanks