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Discussion Starter #1
I bought an 09 G6 last year. It had been in an accident (which may or may not have anything to do with the issues I am having with it). The car drove perfect for about a month - no issues. Then...

Problem 1 - While sitting at a stop light, all the gauges on my dash went off. The low fuel light comes on (probably because the gas gauge is at 0), No Traction Control light, Check Engine Light, etc. In other times that this has happened, I was able to notice that speed-sensitive sounds goes off, as does the A/C. The radio and 'blower' are still on, but just 'basic'. The car is still running and is driveable (if you can guess your speed), but it shifts very rough.
Sometimes, everything comes back up on it's own. Sometimes I have to hit a big bump (and I mean a BIG BUMP) and everything will work. Sometimes I just go home and shut it off. If I shut it off with the gauges not working, the car will not restart...unless I set off the car alarm - which will work as a fix 98% off the time.
The first time it happened and the gauges came back up, we had the codes read at AutoZone. I don't recall what they were (something to do with communication bus?), but if I get this issue again soon, I will post what they are. Took it to the dealer the second time it happened and after hours of diagnostics, they had me replace a connector that plugs in to the front of the computer - they said it was damaged (likely from the crash). My father-in-law (a retired mechanic) replaced it and I had no issues for about a month.

I just found this thread on the forum,
http://www.g6ownersclub.com/forum/showthread.php?t=11062
so I will have my husband check to see if that helps, but any other ideas would be appreciated.


Problem 2
- Sometimes when I go to start my car, it won't start. Not even trying to crank at all. The relays are clicking over (according to my husband), but nothing. Completely by accident, we discovered that if you honk the horn while trying to start the car (begin honking, turn key, stop honking) the car will start and run like a champ. Although this 'fixes' our problem, it is a bit annoying to have to your car not start and then lay on the horn to get it to work.


I used to only have one of these problems about once a month, so I just kind of dealt with it. Lately I have had a problem with it about 50% of the time I go to drive it.

Any insight on where to start to get a permanent fix (or at least one better than honking the horn or setting off the car alarm) to either of these problems would be greatly appreciated.
 

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Do to accident, I would check for a ground not connected. Electrical will do strange things searching for a ground.
 

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Discussion Starter #3 (Edited)
I found the invoice from the first trip to the dealership. The codes they read were:

P0700 Transmission Control System Malfunction

U0073 Control Module Communication Bus OFF

U2105 Lost Comm with Engine Control System

U2106 Loss of Communication with Transmission Control System

U2107 Lost Communications with Body Control System

U2108 CAN Bus Error ABS (4L30-E Transmission) Conditions

U0198 Lost Communication With Telematic Control Module
 

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Did you ever find a solution to this? I have the same symptoms, though it has only happened once so far. I was in an accident as well. I found if I let the car sit for 5 minutes then restart it, it started fine. The problem hasnt come back yet, but I would really like to know what it is. Thanks!
 

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Those codes taken together indicate a problem with the high speed GMLAN bus (the digital control circuits). It could be (& often is) an intermittent problem. If intermittent, this is often caused by an intermittent short to ground somewhere on the GMLAN bus. Restarting the car is essentially the same as rebooting your computer. The codes will be stored in nonvolatile memory & the bus function is restored until the next occurrence of the short circuit. You'd need to look at the freeze frame data with a tech 2 to get more details. This is not a DIY repair issue.
 

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is it possible to just replace the control board?
There are several "control boards". Think of your car as a distributed network of computers all connected by high speed data cables. The computers are constantly communicating with each other. If one of the data lines gets interrupted, the network figures that out pretty quickly & sets codes.
 

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Discussion Starter #8
Did you ever find a solution to this? I have the same symptoms, though it has only happened once so far. I was in an accident as well. I found if I let the car sit for 5 minutes then restart it, it started fine. The problem hasnt come back yet, but I would really like to know what it is. Thanks!
No solution yet. I've been driving our spare car pretty much everywhere for the past few weeks so I don't get stranded somewhere. Saving up $$$ for what I expect to be an expensive trip to the shop. Hoping the dealership will be able to get the problem fixed this time around. I should be bringing it in within the next week - when I hear something from the mechanics, I'll let you know.
 
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