sleepy hollow

My wife's 2005 CLK320 Cabriolet has 110K miles on it. We had a very humid rainy weekend and the car was parked on the driveway instead of in the garage as usual since I was working in there.

When I pulled the car back into the garage late in the day and pulled the key from the ingnition, she shut down apparently normally, but a few seconds later the radio came on and the cluster came on as well. It appeared to be cycling through something as the gauge would blink every 20 seconds or so. After turning off the radio, it came back on again within a minute. I tried various modes and none stayed off (e.g., CD mode).

I wonder if this could be a bad relay. I have been disconnecting the neg batt cable to shut down power between drives (until I can get time to diagnose or get to repair shop).

Any ideas?

Very strange indeed.

Thanks.

Rudeney

Its not a relay. These devices are always powered, and respond to wake-up commands send over the CAN bus. I;d check your vehicle battery voltage. Low voltage can cause weird electrical issues. It should be 12.6v at rest, no less than 11v during cranking, and 14v at idle.

sleepy hollow

Thank you, Rodney, for your advice. I will check it today. It's a fairly new battery, but so what? Time to eliminate it as the cause if possible.

sleepy hollow

Ok, the problem mysteriously went away until last week and is back again. Here are the symptoms:

• remove key after shutoff, flickering begins about every 5-6 seconds on radio "dash" backlight
• Eventually the radio will come on tuned to the lowest FM freq with one of the flashes
• Radio will not stay off. Push power off button, turns off, flashing cycle starts again and radio comes back on within a minute or less
• Only way to drive it is to disconnect battery after shutdown
• One time this week the symptoms were different - fog lights began flashing. I believe this could be low battery in siren.
• Wonder if low battery in siren could be causing this whole mess?

Thoughts? Anyone ever see this problem?

Rudeney

I doubt it's the siren battery. If you suspect it's bad, I'd unplug it (it's located behind the front passenger wheel - remove the fender liner for access). It may, however, be the vehicle battery. What's the voltage at rest/start/idle? Should eb 12.6v/no less than 11v/14v.