ECM / Tune Issue

[Brezick]

Car is 2013 5.0 A6 with hellion TT kit. Custom tune has been on for over a year and running fine until recently.

So I have been having issues with my car not starting and what seems like the ECM is corrupted. All other electronic devices work just fine. Besides the Hellion Kit, which has been on for over a year and running fine, I did put a 2-step on which was already removed.

I contacted SCT and they were great in building a recovery file, which was able to unlock the computer and allowed me to return to stock and re-upload my tune. The car sat for a week and it happened again. I tested the battery and was at 89% and 12.1 volts after sitting for as week. Again SCT sent the recovery file and car was running fine. That was yesterday. Today, I check and again, the car will not start and the SCT handheld is unable to communicate withe the ECM.

I dont think the battery is bad, so buying a new one probably wont help, I am just not sure if my ECM is just messed up and needs replaced. I can't really think of anything else that would be causing this overnight.

 

[nyuk98GT]

Brezick,

Got a Mustang friend who can swap a good battery with you for a week or two? Better yet hook up a Battery Tender (or similar device) to see if the 'no start' issue goes away. That (last option) will give you a definitive answer on the health of the battery.

If there is a light drain on the battery then it may fall below the minimum capacity required to keep the multitude of computers alive in the car.

HTH,

Chris

 

[Jumpmaster2015]

Electrical troubleshooting 101

Start at the battery and work your way up from there (alternator, shorts, etc) before assuming a major component is bad. Also, has it been getting cold at night? Batteries issues tend to show up when cold weather appears.

 

[Brezick]

I have tested the battery both times the past two weeks, both times there was >85% charge and >12 volts. I know I probably should just get a new on in there anyway before I go and mess with the computer.

I have a trickle charger that I had on it from time to time and that did not help.
Alternator seems fine as when i did have it running Sunday, voltage held at 14.1-14.5 steady.

 

[Jumpmaster2015]

I have tested the battery both times the past two weeks, both times there was >85% charge and >12 volts. I know I probably should just get a new on in there anyway before I go and mess with the computer.

I have a trickle charger that I had on it from time to time and that did not help.
Alternator seems fine as when i did have it running Sunday, voltage held at 14.1-14.5 steady.

Ok, does the motor crank when it does not start? Hopefully your PCM is ok!

 

[Brezick]

The motor does not crank. The dash is all lit up like you would see when you first start to download a tune.

 

[Jumpmaster2015]

The motor does not crank. The dash is all lit up like you would see when you first start to download a tune.

Sounds like it runs fine when it wants to. This feels like something simple. Good luck!

 

[Brezick]

Thanks, i know its something dumb because when it is running, it runs. So something is causing the computer to wipe or corrupt, whether its a random loose wire, something got wet that shouldnt, etc.

I at least got the car under cover for the winter and am pulling the motor in the spring, so Im half tempted to leave it as is, get a new battery come spring and just start from there.