LameS4

I have a 2001 S4 that has some funky electrical issues. Not sure if this is relevant, it may be, but - the car was sitting for about 4 months and the battery died.

1. Brake lights on either side are not working and all bulbs are good. The light in the rear window works and always has. Prior to the car sitting, the driver side brake light always worked but the passenger side randomly stopped. I replaced the brake switch but no change. Signals work, and when I turn on my headlights the running lights or whatever work.

2. My wipers just started to act up. This morning I hit my wipers to spray and clean off my windshield, after they just kept going for a while then stopped. I could hear the relay clicking but havent checked it to see what the issue is. Could it be the relay or part of the arm or something?

Wipers are less of a concern since I'm not trying to get a ticket for no brake lights. Any insight on this would be greatly appreciated.

Redd

No idea about your wipers but most cars have a "brake light controller" or relay module and I'd guess with all Audi's there's a little computer in there. If that module was bad, it could explain brake failures and power drain. Sounds like time for diagnostics.

LameS4

If you are referring to the brake light switch, that has been replaced.

It is strange because the light in the rear window works, but the rears do not..perhaps some moisture got into the sockets or something when it sat..must investigate after work.

Redd

No, usually the switch is physically on the brake pedal, and usually the switch only supplies power (hot or ground) to a brake light RELAY, or a computer, which is installed under the rear floor, or the rear quarter panel, or someplace equally invisible. The last time I had a brake switch that actually directly turned on the brake lights was, well, in a time when computers couldn't FIT in cars.

And then there are some truly bizarre threads about VW and Audi products that have bad coolant temperature sensors. Huh? Yea, apparently if the seal on the sensor fails, it can lead to a section of the harness wiring--including the brake lights--being flooded with coolant.

You just couldn't make this stuff up if you tried. COOLANT in the brake lights, creeping down the wiring harness from the engine.