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I have a 2008 very clean LS3 with 31K miles. It was a "water damaged" car and had 17K miles with damaged/ recovered title when I got it for cheap. It runs like a watch and perfect in every way... except- the park shift lock solenoid (good solenoid) does not get juice until about 30-120 seconds of having your foot on the brake. Then all the sudden "click" (sound of solenoid engaging) then OK. Pretty sure the Microswitch is bad under the console. I am afraid to take the plastic cover off!
Next issue now. 2 years ago, can't connect to computer port (ECM) for inspections, etc. Connect ANY scanner and SOMETIMES, LOCK symbol sometimes comes on and car goes into a "limp mode" won't shift gears. Solution- RANDOM: turn car off. Click FOB to lock and unlock a few times. Clears- PERFECT - for a while. Or just wait 10 minutes for LOCK (yellow security lock on left lower side of cluster, BTW). ALSO of note, when this happens, the shifter lock solenoid can be heard clicking on and off.
Now it has gotten worse. Lock symbol appears RANDOMLY like a turn to the right under acceleration may cause this. Or going from Drive to reverse and back with a little acceleration. Car shuts down and won't start, door solenoids stick. Can't shut doors (or open). ALL gauges ZERO out (except Alternator gauge is OK). Try to start and NADA, ZIP except light ACCY in push start button light. SOLUTION: lock/ unlock repetitively with key FOB. (Door lock unlock buttons do not appear to respond. And if the door is open, the door solenoids (driver and passenger) are in CLOSE position and an attempted door close and BAM! strike pin HITS the closed solenoid captivating C latch. Turn signals stop working. Seat belt reminder does not work. Alarms sequence through the display - Antilock Brake failure (with red brake light lit), Service Vehicle, Fuel system, Low fuel, but mostly BCM items (?) with the exception of those power train ones. I have a loose ground or bad computer. Another thing, the exhaust cutout activates every time this happens. The "BMW Limp mode" where it stays in 1st or second gear does NOT always happen. I drove it 20 miles like this yesterday. You have to pull the manual door lock release to get in and out (windows work but the window crack feature does not work). Loose ground or bad computer? I wonder if the computer connectors are bad from the Hurricane Sandy flood event.
There is a loose ground SOMEWHERE! Anyone know where it might be? Or BCM/ and or ECM going bad- corroded connectors from Hurricane Sandy flood damage... car was partially submerged. ECM/PCM or whatever you call it is down low behind passenger side fender which makes it appear to be a pain it the butt to get to it. But! maybe I should start there. Disconnect battery and pull the connectors and inspect for corrosion? ARE THERE ANY MULTI JUNCTION GROUND POINTS that are easier to get to that may cause random electrical issues?
With any water intrusion into an electrical system, there will be corrosion at connectors, grounds, etc.
Since the C6 is a ground activated system. finding and cleaning those are of paramount necessity. That will be a task in itself, as you will have to remove some interior trim, etc. to get at some of these. The BCM connectors will likely have to be checked, cleaned, etc to assure that you can stop any further corrosion creepage.
You should add dielectric grease to all the pins, and grounds that you clean.
I tried to insert the electrical grounding section from the service manual, but it is too large to go in this post. It will include ground locations with diagrams, Connector locations, Electrical Splice locations, etc. PM me your e-mail, and I'll send it to you.
I have taken a snapshot of the grounds and location that is in the section, but the diagrams are numerous so I have not done those.
C6 random intermittent electrical BCM issues
