Uncontrolled voltage 2017 GT350R

[RobeRob]

Hi guys I have a 2017 GT350R. It has about 8300 miles on it. I haven't been able to drive the car because the charging system voltage is sometime as high as 16VDC. I 've been told I have an open A, B signal which I believe are the comm wires from ECU to alternator and vice versa. Anyway the car has been to three dealerships and two electrical shops and no one has been able fix the car. Has any of you guys experienced anything like this. Also I started the car today and I saw 16VDC during idle. Any thoughts???

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[MiamiGT350]

What fixes have they tried that didn't resolve the issue?

 

[RobeRob]

Three different alternators, alternator wiring checked supposedly.

 

[MiamiGT350]

Three different alternators, alternator wiring checked supposedly.

Assuming these things are fine... the PCM manages the voltage, so I would be asking the dealer to re-flash/re-program the PCM or replace it.

Also probably doesn't hurt to do a BMS reset: https://www.mustang6g.com/forums/threads/bms-reset-no-tools-required.151602/#post-3091806

 

[Postal Bob]

Original battery?

 

[RobeRob]

Yeh, that's gonna be a problem. The car has a lund tune and is supercharged. Not sure if they reflash the ECU I'll be able to upload the Lund tune back. Also what is the correct BMS reset for the GT350

 

[Postal Bob]

Yeh, that's gonna be a problem. The car has a lund tune and is supercharged. Not sure if they reflash the ECU I'll be able to upload the Lund tune back. Also what is the correct BMS reset for the GT350

Here is the BMS reset procedure. But it's used when replacing the battery. How old is the battery in the car? And if replaced, did you ever do a BMS reset?

Procedure must be carried out within 10 seconds:

1. Switch ignition on (engine off)
2. Pull and release high beam 5 times.
3. Press and release brake pedal 3 times.
4. If successful the battery light will flash 3 times within the next 15 seconds
5. BMS reset completed.

 

[RobeRob]

Yeh I have a new battery. And I have reset the BMS a few times. I asked because I wasn't sure I was doing it right.

 

[Kobi Addiction]

Exactly what type of battery is on the vehicle?

I had these types of voltage issues when I installed an aftermarket battery with a “restart” (jumpstart) feature that was not playing nice. Once I removed it for one without the feature, the car has been running normal.

 

[RobeRob]

yeah I had an agm battery but went to ford and got the battery that goes in the GT which is a better battery. I was looking at alldata and it looks like the command signal wire go to a connector before they go to the ecu. Im gonna check that connector and keep you guys posted.

 

[RobeRob]

Hey guys. Just an update. The cars voltage was spiking up to 16vdc. So I flatbedded the car to the dealership. So now the car is at the dealership again. Now I'm being told that its the PCM and the gateway module. Total 2K. And because the car has been supercharged I had to take my handheld to them so that they can download the tune. Anyway at lease these guys seem to know what they are doing. Second summer in a row I haven't driven the car. I hope this works.

 

[RobeRob]

Q. Has anybody had a PCM go bad? I contacted Lund and was told that dont use the SCT devices anymore so now I'm forced to try the SCT hand held device that has the original tune which they are saying may be locked to the original PCM. WTF!!!!

 

[RobeRob]

Update: So the PCM was changed out and the gateway module. Reflashed and the Lund tune was uploaded.During the drive home the battery light came on twice. Called them to let them know. I was told they would get back to me. NO CALLS BACK SINCE TEN DAYS AGO. The car is worst now than when I gave it to them. And I got charged $2300 and $200 for the tow. WTF is goin on with the lack of expertise at these Ford dealership!!!! So now I have contacted FORD corporate and made a claim. Never thought something as simple as a charging system issue would be soo hard that Ford service techs couldn't fix this kind of issue. I believe I may have to get a lawyer involved.

 

[sublime1996525]

Aw man I’m sorry to hear about this. Dealer techs are very hit or miss. More so miss, unfortunately. I hope Ford will do something to help out. Have they tried replacing the plug on the harness that plugs into the alternator? It’s essentially made of fairy dust so it’s very sensitive to any forces movement.

 

[RobeRob]

Yeah, I'm learning this unfortunately.
So I go back to the dealership and let them know that I have put in a claim at Ford corporate. Now they are mad at me, but from my perspective they just charged me $2300 and assured me it was the gateway and PCM modules only to have the car do the exact same thing.
I always wanted a shelby and waited until all the kids went through college and figured now was my time to finally get something I wanted to drive. Silly me cause I'm still thinking old school. SATISFY THE CUSTOMER. Well the jokes on me. Thanks for the paperweight Ford!!!!

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