C43 - Strange problem with flashing lights

[e harmon]

I'm having a strange problem with flashing lights on my 1999 C43. Occasionally, while the car is parked, the fog lights, blinkers, and tail lights will start flashing and the interior lights turns on. It's almost as if the alarm was triggered, but the siren does not turn on. This happens even when no one is near the car. The lights stop flashing when I press the unlock button on the remote.

I experimented with the tow protection defeat switch, and even with this active, the flashing lights still happen sometimes. I also tried triggering the alarm with the panic button and by arming the car and opening the hood from inside. The alarm responds to both of these things, and the siren works.

To the best of my knowledge, the car is electrically stock except for a replaced head unit using the VW harness and pnsji's instructions elsewhere on this board. This problem occured both before and after the HU was changed.

Anyone have any ideas or information? Thanks very much in advance.

e harmon

[LGDBenzo]

I have the same problem with my c280 (99). did you ever find out what the problem was?

[e harmon]

Unfortunately, I never learned what was causing that problem. It seemed to come and go, sometimes for weeks at a time. Over time, it seemed more likely to happen if I used the trunk (thereby opening and closing the trunk lid), but this may have been coincidence.

I wish I had better information for you. Good luck with it.

e harmon

[therock2689]

Thats weird man. I dont know what to say other then you car is insane. you havent done anything other then the HU, where would it go wrong. IT could be something in teh alarm system that may be causeing it beacause everthing goes off except teh siren. i would say to pull teh fuses on teh alarm and see what happens then. Other then that, i dont know, just something weird you might have to deal with.


Rock

[Proven Guilty]

first thing i would have checked was the ground for the alarm system, and changed the batteries in the key fob. hell, even as a test run, take the batteries out of it for a week when its parked for the night to see if the panic was somehow being triggered repeatedly.

afaik he sold the car about 5 months ago. that thing was so badass

[LGDBenzo]

I figured it was the anti tow alarm sensor, which is in the trunk. I had noticed a few days earlier there was a damp smell coming from the trunk ( some water had spilt from an old water bottle I was carrying). It must have gotten into the electronics. I disconnected the sensor and as it dried out it never happened again. The car is fine now. wierd!