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I have a 2005 C6 which I have owned from new. It has recently developed a series of electrical problems.
The first is that the external door realease switches will not work periodically. This normally occurs after the trunk lid has been opened. I can get into the car with the key and manual door release but this triggers the alarm. To disable the alarm I press the brake pedal!
The second problem is with the power supply to the driver's seat adjustment and the steering column adjustment. We have traced this back to the panel in the passenger footwell and there is no power feed. All the fuses are fine and the passenger seat works.
The third problem is an intermittent power failure to the dashboard instruments. This only happens whilst driving which can be a bit scary. This is fixed by disconnecting and reconnecting the battery. This was happening about once a week but has not happened now for about 2 months.
The car is used daily and covers about 1000 miles a month.
Intermittent problems are the most difficult to solve. Keeping track of the issues involved should help point the way. The first thought I had while reading this was a bad connection somewhere. Maybe a loose ground. Is the battery voltage near 13.8 before starting the car? Are the battery terminals clean and tight?
I started having issues like this on my C5 and it ended up being the battery. Battery voltage was in the 12's and climbed after starting the car.
No clue about the brake pedal silencing the alarm...thats a new one for me. I would think you need to pull the codes with a code reader to start looking at things. The telescoping steering wheel probably gets its power from the seat control module therefore I would be looking at the seat to car interface connectors at the bottom of the seat. Check them for moisture contamination, clean as needed. Also check every fuse in both fuse boxes.
There have been bad "new" batteries, so measure the voltage across the battery with the ignition off. You need to see a minimum of 12.5vdc for things to work correctly. Check all battery connections and the connections at the starter solenoid which is where the battery, alternator, fuse boxes and of course the starter, all come together. Remember that the solenoid is electrically hot.
My company mechanic has just checked my "new" battery and the voltage is 12.3. The charging system is working fine so it sounds like a warranty claim on the battery. Thanks for your help.
My company mechanic has just checked my "new" battery and the voltage is 12.3. The charging system is working fine so it sounds like a warranty claim on the battery. Thanks for your help.
Glad to hear you found the culprit. Low battery voltage on these cars creates some weird problems.
12.3 VDC is normal for a battery that is sitting idle. If the engine is on and alternator is charging it should be around 14.3-14.6 depending on the state of charge of the battery
I had a very simular issue with the IPC. I also had a NO START issue at the same time....
When I pressed the START button, the IPC went DEAD (excepy for the check eng light) and the car would NOT crank.
My issue ended up being a bad ignition switch. Popped in a new one and its been 100% ever since.