2013 GT cold start issues

Brezick · Jan 21, 2017

My 2013 GT A6 is having issues starting every morning. It wont even turn over, but after a few key on key offs, it starts. I am thinking its a short or lose wire somewhere, but I dont know where I should look.

What happens is I get all the dash lights and ------ miles, so I know the dash is not able to communicate with the PCM. However, if i cycle the key a few times, it finally decides to start. So I do not think the PCM itself is bad because when it starts, the car is good, tune is still applied, etc.

It also only happens on cold starts. If I run the car, stop and let it sit for up to an hour, it fires right up. I only get the miscommunication after letting sit over night.

Battery and alternator tested good, all other electronics are running fine.

The car did previously have a 2 step and transbrake, so there were two wires cut on the trans harness, but they were removed and soldered back together. I triple checked these were good.

KatoS197 · Jan 21, 2017

Does it do this with both keys?

Brezick · Jan 21, 2017

Just went out and checked, both keys have the same result.

KatoS197 · Jan 21, 2017

Brezick said:
Just went out and checked, both keys have the same result.

Damn. It almost seemed like one of your keys was on the fritz. Ruled that out.

travelers · Jan 21, 2017

I would start by pulling the batt terminals and clean them.

JEWC_Motorsports · Jan 21, 2017

What kind of test was run on the battery? If you didnt do a load test, you need to.

Coosawjack · Jan 22, 2017

Sounds like a bad relay to me......check the starter related relay under hood....it's #52 on my 2014 car!! Just swap it with one of the other ones to see if it fixes it......has happened to me on older cars!! :omfg:

Good Luck!! :thumb2:

Brezick · Jan 22, 2017

travelers said:
I would start by pulling the batt terminals and clean them.

jewc75 said:
What kind of test was run on the battery? If you didnt do a load test, you need to.

Terminals are clean as can be, never had much corrosion. Battery has been load tested. Tool is pretty old, but still worked. Also as I mentioned, all other electronics and power accessories are running at full just on battery, so its got good juice.

Coosawjack said:
Sounds like a bad relay to me......check the starter related relay under hood....it's #52 on my 2014 car!! Just swap it with one of the other ones to see if it fixes it......has happened to me on older cars!!

Thanks, I will take a look. The Hellion kit moves the fuse box around, so I did not want to pull things out to get to it unless I had some things to check.

Good Luck!!

redfirepearlgt · Jan 22, 2017

First it would help to know for troubleshooting if the car is a base model GT A6 or Premium model GT A6. The instrument clusters are different.

1.) Next time you enter the car, place the key in the ignition with the door remaining open and doing NOTHING ELSE. Do you get the key ignition chime warning? If not then turn the key to run (not engine start) and observe and record what you see and hear. From there try starting the car and observe and record what you see there.
2.) Now assuming it does not start (keeping the door open) do what you normally have to do to get it to start and record your observations.
3.) Once started and warmed up, with the door still open shut the car off. Repeat step one above observing and recording what happens at each step. Omit nothing no matter how insignificant you may think it is.

Provide everything you observed in this order back.

Through this method we may be able to use some of the diagnostics through the instrument cluster of the 2011 tech manual on line to narrow the problem down. Its obviously not a power issue as you have stated.

Its presumably apparent the load test on the battery is good and we have good reliable power.

If the SJB for whatever reason does not see key in ignition (which is confirmed by the key in ignition door chime) other things will not happen such as starting the car, etc.

Brezick · Jan 22, 2017

redfirepearlgt said:
First it would help to know for troubleshooting if the car is a base model GT A6 or Premium model GT A6. The instrument clusters are different.

1.) Next time you enter the car, place the key in the ignition with the door remaining open and doing NOTHING ELSE. Do you get the key ignition chime warning? If not then turn the key to run (not engine start) and observe and record what you see and hear. From there try starting the car and observe and record what you see there.
2.) Now assuming it does not start (keeping the door open) do what you normally have to do to get it to start and record your observations.
3.) Once started and warmed up, with the door still open shut the car off. Repeat step one above observing and recording what happens at each step. Omit nothing no matter how insignificant you may think it is.

Provide everything you observed in this order back.

Through this method we may be able to use some of the diagnostics through the instrument cluster of the 2011 tech manual on line to narrow the problem down. Its obviously not a power issue as you have stated.

Its presumably apparent the load test on the battery is good and we have good reliable power.

If the SJB for whatever reason does not see key in ignition (which is confirmed by the key in ignition door chime) other things will not happen such as starting the car, etc.

Car is a base A6.

1 - I do get the key chime when the doer is open and key is in.
When I turn the key on, most of the dash lights turn on, and I get the messages Service Advancetrack, Check Charging System, and Mileage -------.

2 - I know when it will start, as when I cycle the key on, the cluster will read the mileage and will not have any service messages. This just doesnt happen until a few cycles.

3 - As soon as it starts and gets up to temp, for the following 45 minutes, i could not get it to fail, it will start every time when warm.

Edit - as an additional note, when it wont start, my SCT handheld cant even read the PCM or upload a tune. As soon as it starts, it is back to reading. However, i had SCT write their recovery file twice for me and both times that file was able to be uploaded while the car wouldnt start, and the gauges went back to normal afterwards.

redfirepearlgt · Jan 22, 2017

Okay. Thanks for that. The key chime indicates that the SJB is seeing the key and is responding accordingly as I understand it. That doesn't however rule out the SJB overall as being the cause but I am not going to just jump on that out of the gate.

I've been breezing over the SJB and power distribution wiring schematics as well as how the instrument cluster ties in looking for a common device shared by the starting circuit and the Instrument circuit. The alarms and OD dashes are puzzling me. I hope to have a free moment to read deeper on the instrument cluster section to see if there is anything significant with ------- and no start.

While looking at the schematics I began to wonder if the PCM power relay could be the culprit. It would be worth while to swap that out with another like relay from a non essential system to see if the problem goes away. Relays can become intermittent sometimes. Also inspect he socket in the Battery Junction Box (BJB not SJB) where the PCM power relay is located for corrosion when you do try the swap.

Meanwhile I will read up a little more to see if I can find anything specific about the info center advisories you are seeing and what they may all have in common aside from the CANBUS.

2013 GT cold start issues

Brezick

Yinzer

KatoS197

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Brezick

Yinzer

KatoS197

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travelers

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JEWC_Motorsports

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Coosawjack

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Brezick

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redfirepearlgt

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Brezick

Yinzer

redfirepearlgt

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