Walked out of work yesterday, got in the car, pushed the start button, everything shuts off, click, no start. I let go of the button, and after a few seconds, 4 or 5, the dash lights back up, all the gauge needles flip over and back, just like when you start it up, air starts blowing, and the radio comes back on. Its NOT in accessory mode. Hmmm. Push the buttton again, same thing, everything dead, then after a few seconds, everything pops on like accessory mode. Third time, no start, I get out of the car, everything pops on again, and now I can't get back in the car to stop it, I'm locked out. I walk away a good distance, I can STILL hear the radio, walk back, now it opens.

I give up and call Security, who come over to give it a jump. I hook it up (and did it correctly), push button, nothing, try again, try again, the third try, it starts! So I unhook, drive it home. When I pull in, shut it off, then restart it, no problem. Hmmm, maybe dead short, bad battery?

Get up this morning, it is again doing the Crazy. No start, count 3 or 4 seconds, then everything pops on. And now it won't open the door to let me out. Thankfully, I'd put the top down the night before, so I just climbed out. Well, hmmm, maybe battery, so I go get a new one and load it. And the old battery was completely dead, they said. Try to start it, same issue. Except, on the third or fourth try, I first put it in Accessory mode, that lights up just fine, then I hit the start button, and it fires up.

Ring a bell for anyone? Start button shorting, maybe?

 

Don't know how old your battery is, but if battery cables are clean & tight, change the battery. I manage an auto repair shop and you would not believe the issues that we see from bad battery's. I just changed the battery in my wifes 07 malibu, the o.e. battery was swelled and acid was starting to form on the holdown bolt in the bottom of the battery case. you got nothing to lose by replacing the battery on a high dollar car, you won't be happy when it needs to get towed.
Good luck

 

My '07 did almost the same thing. First the dealer changed the alternator then a week later, same thing. They ordered another alternator, put it in and it "burned up", their words. After some more troubleshooting they found a short in the harness from the battery to the starter. I was also getting the service charging system message along with low voltage that would recover to normal as soon as I started driving. Check your starter connection. It may be loose and causing the intermittent starting. Hope this helps.

 

I'd do both of the above posts, but you could be right with the starter button OR it could be the battery. You might also check that HUD add, and see if everything's a-ok there, too. I see your car's an '09; it really shouldn't be having batt. issues, but who knows?

 

I'd be looking at the solenoid as that is where all of the electrical comes together. Battery, fuse boxes, alternator and of course the starter

 

I have a 06 MN6 Coupe. I had the exact same thing happen to me. My OEM Ignition Switch had a cracked front cover so, I ordered a new Ignition Switch. The day it wouldn’t start, I removed the old cracked switch and during the removal to install the new one, the dash came back to life. Hmmmmm....

I installed the new switch because I already had the old one ready to remove. Heres what an Ignition switch looks like inside:









Some months after switch replacement, the same no start/dash issue happened again.

You most likely do NOT have a battery or alternator issue. My battery was brand new at the time and the connections were pristine clean and tight. The charging system works perfectly.

The problem seems to center around a START SEQUENCE ISSUE. There are THREE schematics that this problem centers around. Having an understanding of each one is important to be able to troubleshoot this problem. To figure out what part of the circuit is failing, working backward from the starter to see what voltage or relay signal is not happening would most likely be the easiest way to figure out what is bad.

The Start Switch causes a start sequence to initiate. Its fairly complex but not impossible to understand. Here is the start/ignition schematic:



Next is the Crank 1 circuit:



Next is the Crank 2 circuit:



For those of you that had C5s and thought the starter/crank circuit was complex This is a nightmare!!!!!! This makes the C5 look cave man simple!!!!

That said, sooner or later, we will have this circuit all figured out and the problem figured out. It may take a little time but, we will solve it.

BC

 

Examining this circuit a little closer, take a look at the CRANK RELAY #43. The BCM and the ECU have to be happy to supply the crank relay a supply voltage and return path to make contact and initiate the starter solenoid.

If the required LOGIC anywhere in the circuits between the BCM and ECU are not correct, it will NOT allow the starter to crank the engine. It will however cause the IPC to do all the stuff it suppose to do during the start sequence.

BC

 

I had no idea the starter switch had that much inside. Obviously there is a lot more to the start systems on the C-6 than that of the C-5

 

Me either till I opened I up. If yours ever cracks, the crack will NOT cause issues with swich operation.
BC

 

Bill, you are truly an asset to this forum with all your posts with great information.

But you have incessant electrical problems...do you live on top of a radioactive Love Canal or something?

 

Come ON! I only live in the SALT ENCRUSTED, CT Tundra! That couldn't have ANY thing to do with a little electrical issue, could it????

With the C6,,, I think i comes with the territory. Ive been pretty lucky with the 06. Only a few issues and I solved most all of them. I sold it and told the person that I sold it to that I would not leave him in the ditch on things that might go wrong so, were staying in touch. Like I said, its not acted up since I fixed it and I will stand behind my word.

I have an 11 Grand Sport MN6 Vert now. Hope it stays trouble free!!!! WE WILL SEE!

BC

 

That's right...you live near the ocean, I'd forgotten. I've been following your electrical threads for years and forgot about that. I used to work on the ocean, that salt air rots stuff in odd places for sure.

Thanks again for your posts. And congrats on the new ride!!

I'm a GS vert fan myself....

 

Thanks to everyone for the responses, some good information. On Saturday afternoon, I took it over to the dealer and dropped it off. Monday lunchtime, they call and say its ready. They say, the battery is fine, the alternator is fine, they tightened a "cable", and that was that, it works just fine now. They didn't say which cable, or where. I suppose it could have been the hot down at the solenoid, but how that would have gotten loose?? The terminals were all clean and nice and tight to begin with.

I've got 43K miles on my baby already, 2.5 years, so I suppose I could understand a dead battery, though in fact it may have been alright and just needed charged. Ah well.

In any case, I will see how it does, and will try not to act shocked if it turns up again. Damn gremlins

 

If it happens again, press the OFF button and see if it turns OFF and then press the ACC button and see if it will enter ACC.

If it enters ACC, then press START and see if it will start. I'm trying to figure out what LOGIC works and what doesnt.

Bill

 

there is a lever to open your doors that is beside the driver and passenger seats on the floor...use these to get out when there is no power.

but hey, nothing wrong with getting out it in style..

 

Yeah, I knew about the lever, but I don't know how it works, didn't know if it would have any negative consequences to the electronic locks. I'm sure it doesn't, but I dunno.

 

It absolutely doesn't. Try it before you need it! Also good idea to find the door release in the hatch area before you need it.

 

You also need to know that there is a KEY LOCK for the rear hatch. If the battery dies, you use it to open the hatch. Once the hatch is open, you pull the DOOR RELEASE cable on the rear of the drivers side wheel well. The release cable sticks out of a slot in the carpet The manual gas door release is there also.

Look up under the area where the lisense plate is. You will also see a rubber button that will open the rear hatch/trunk.

 

Damn it, I did not know about the door latch in the trunk. Sigh. Next you'll tell me I have to change the oil once in a while, or somethin'.