Uncontrolled voltage 2017 GT350R

[sublime1996525]

I am sympathetic, but the car was tuned, brought in for diagnostics and troubleshooting, a repair attempted, and didn't fix the problem.

What are the terms and conditions when you bring a car to a dealership? I image there is a diagnostic fee applied, but absorbed by the repair. What happens if the car isn't repaired by the repair?

I'll throw out the obvious that has probably been addressed. I would have started with a new battery along with an immediate BMS reset via forscan. I've seen these same symptoms, but the battery has to be topped off with a fresh charge along with an immediate BMS reset.

What's left? New battery, New alternator.... done.

Beyond that, you are looking at a PCM or a wiring issue.

Agreed. I just went through this. New battery, alternator, and pigtail. Problem solved.

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[RobeRob]

Thanks for the help Cobra Jet. Imma dial it in. I went to the auto electrical shop today that's near me but they don't speak any english.They are supposed to be really good so Im gonna take one of my kids back over there to tell them what I need because they grew up speaking spanish and are fluent.

 

[RobeRob]

ok I read the thread. So if Im reading it correctly what was done is just remove the alternator connector and the car will run perfectly. Is that correct?

 

[Cobra Jet]

ok I read the thread. So if Im reading it correctly what was done is just remove the alternator connector and the car will run perfectly. Is that correct?

Based on the FF thread, if your alt has that 3-wire harness, it seems those users were disconnecting it and finding that the charging went back to normal spec.

This is the direction they were given by Ford Performance. So you wouid have to check your alt, it if has that harness, disconnect it and see what happens.

I do not know what will happen… The way it was discussed in that thread is that harness is the communication link between the PCM and alternator for what was causing the voltage spikes.

If anyone else has any input, please feel free to speak up.

I don’t have any schematics to even review or confirm if all S550’s have that 3-wire alt harness or not.

 

[Egparson202]

Based on the FF thread, if your alt has that 3-wire harness, it seems those users were disconnecting it and finding that the charging went back to normal spec.

This is the direction they were given by Ford Performance. So you wouid have to check your alt, it if has that harness, disconnect it and see what happens.

I do not know what will happen… The way it was discussed in that thread is that harness is the communication link between the PCM and alternator for what was causing the voltage spikes.

If anyone else has any input, please feel free to speak up.

I don’t have any schematics to even review or confirm if all S550’s have that 3-wire alt harness or not.

So, let me get this straight… The conclusion of the FF thread was that the super-fragile 3 wire harness can be just… unplugged?! If true that would be equal parts ironic and joyous for those of us who have struggled with this gremlin.

@RobeRob, if you can confirm this please share it back here. What a silly and wonderful find this would be.

 

[RobeRob]

I sure will. I wish I would have used you guys' expertise several thousand earlier buuuuuut. I will buy some jack stands and unplug the control connector. If it works I will definitely pass it forward. I dont want anybody else to go through this BS. I also read in another thread that guys have installed a jumper from Gencom to Genmon. So i will remove the plug first then get back to you guys after the holidays. I cant thank you guys enough.

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