Electrical 2007 GT500 electric cuts at 2000 RPM

I8A-VET

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Mar 24, 2018
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Ok, so this issue has perplexed me for over 3 years now. I picked up a rebuilt / salvage title 07 GT500 back in 2015. Everything is near perfect however when I wholeshot the car my guages, dash lights, ABS, and stereo power cycle. It's quite distracting and upsetting when it happens as it's usually when I'm trying to enjoy the power this beast has. I've taken it to the local speed shop who wants a ton of money to analyze the electronics and Dyno the car..

So I've physically checked the ground connections which seem ok (no multimeter testing though). considering it's an RPM triggered event I'm suspecting that it ISN'T a ground issue.

I've disengage the ABS because when the power cycles it instantly turns back on the ABS creating problems.

My suspicion is that the person who rebuilt the GT500 cheaped out on a replacement alternator and either installed a junk GT alternator (not GT500) or perhaps a defective one that maybe sends a surge at 2000 RPM. I just can't think of anything else that involves electronics and would be 2000 rpm sensitive.

I sure would appreciate if an expert from this forum could assist as I'm completely lost. 3 years with the car and I can't take it over 2000 without fearing the unknown...

Thank you in advance whoever you are who will be taking time out of your day to help me.

Carl
 
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Thatsweetstang

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Nov 4, 2013
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I would get the alternator tested since you think it’s a problem, but I would do the wiggle test while the car is running. Just shake and wiggle every connector and wire to a sensor. I’ve had these problems before with Honda’s and specifically our new type R’s, the under hood fuse box had bad internal sauder welds/cracked welds and would cause the cars to cut out under load and stall or throw all the lights on. But those problems took days on days and mutlipe techs to figure it out. It was a lot of wire tracing and schematic work to track it down to the fuse box.

Also you said the car is a salvage, every time some thing stupid happens that isn’t common that for me 9/10 times it’s a ground. Usually they paint the car and put the grounds right back on top of the paint and you’ll have high resistance, if you have high resistance power won’t go back and it’ll find another path back to the battery and power other sensors and cause weird problems. I would remove all the grounds, file the surfaces that they go to, and reinstall and see if that helps. That’s been my number 1 cause of problems with every salvaged car I’ve ever had to diagnose.
 

I8A-VET

New Member
Mar 24, 2018
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I would get the alternator tested since you think it’s a problem, but I would do the wiggle test while the car is running. Just shake and wiggle every connector and wire to a sensor. I’ve had these problems before with Honda’s and specifically our new type R’s, the under hood fuse box had bad internal sauder welds/cracked welds and would cause the cars to cut out under load and stall or throw all the lights on. But those problems took days on days and mutlipe techs to figure it out. It was a lot of wire tracing and schematic work to track it down to the fuse box.

Also you said the car is a salvage, every time some thing stupid happens that isn’t common that for me 9/10 times it’s a ground. Usually they paint the car and put the grounds right back on top of the paint and you’ll have high resistance, if you have high resistance power won’t go back and it’ll find another path back to the battery and power other sensors and cause weird problems. I would remove all the grounds, file the surfaces that they go to, and reinstall and see if that helps. That’s been my number 1 cause of problems with every salvaged car I’ve ever had to diagnose.

All very good suggestions. The wiggle test is easy enough but since the car runs perfectly it'll be a challenge.

Actually the car continues to run even when the electronics glitch at 2000 rpm. I guess that since it doesn't stop running the car must still be getting power to the PCM / ECU? Do you think that's correct. I never really thought about it until now as older cars would always run even without power but these newer cars are computer driven. If the power was truly cut the car would stall or at least shudder wouldn't it?

So if the above is correct we could narrow down the source to the electronics within the cabin and dash. It does power cycle my TCS traction control sensor. That is one of the more annoying issues is that when I'm jumping on it I have the TCS disengaged, once I hit 2000 RPM the electronics cycles and automatically re engauges my TCS.

I bet you are on to something with the grounds. Do you know where the ground points are for the car? I can poke and probe but I bet there is a schematic for that. I bet also there is a resistance rating that could be measured.

Thanks for taking the time to help. I very much appreciate all your thoughts as this has perplexed me for several years.

Carl
 

Thatsweetstang

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Nov 4, 2013
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The grounds look like they are mostly on the passenger side engine bay near the radiator support... I’ll take a picture from alldata on Monday and it’ll probably make more sensor lol.
 

I8A-VET

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Mar 24, 2018
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Thanks.
The grounds look like they are mostly on the passenger side engine bay near the radiator support... I’ll take a picture from alldata on Monday and it’ll probably make more sensor
The grounds look like they are mostly on the passenger side engine bay near the radiator support... I’ll take a picture from alldata on Monday and it’ll probably make more sensor lol.
Thanks! Looking forward to seeing the photo. Unfortunately with Easter and all I haven't been able to get the Stang out of storage yet. Hopefully sometime this coming week... We even had a bit of snow today in Buttalo. Endless winter this year...
 

I8A-VET

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Mar 24, 2018
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Thanks.


Thanks! Looking forward to seeing the photo. Unfortunately with Easter and all I haven't been able to get the Stang out of storage yet. Hopefully sometime this coming week... We even had a bit of snow today in Buttalo. Endless winter this year...
 

I8A-VET

New Member
Mar 24, 2018
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Thanks.


Thanks! Looking forward to seeing the photo. Unfortunately with Easter and all I haven't been able to get the Stang out of storage yet. Hopefully sometime this coming week... We even had a bit of snow today in Buttalo. Endless winter this year...

So I've ignored the issue all of 2018 with the problem worsening throughout the year. Now thankfully it is occuring when I hit bumps telling me that it is a loose ground somewhere. Does anyone know where I should look?

Here is a refresher on the issue:
You
I have an 07 Shelby GT500 that was a salvage rebuild. I purchased it rebuilt. The only problem with the car in my 4+ years of ownership is that the electric cuts out on wholeshots. I always suspected it was a poor ground somewhere but haven't ever identified it. This year I took her out of storage and now am loosing electric power (kills the engine also) every time I hit a bump. I traced the ground to the fender and it seems secure. I pulled on wires around the chassis and can't duplicate the problem unless driving over bumps or spinning the wheels. Any thoughts where to look? I will say that the cables coming off the battery seem quite hot after a bit of driving.
 

I8A-VET

New Member
Mar 24, 2018
8
0
1
50
You
I have an 07 Shelby GT500 that was a salvage rebuild. I purchased it rebuilt. The only problem with the car in my 4+ years of ownership is that the electric cuts out on wholeshots. I always suspected it was a poor ground somewhere but haven't ever identified it. This year I took her out of storage and now am loosing electric power (kills the engine also) every time I hit a bump. I traced the ground to the fender and it seems secure. I pulled on wires around the chassis and can't duplicate the problem unless driving over bumps or spinning the wheels. Any thoughts where to look? I will say that the cables coming off the battery seem quite hot after a bit of driving.
 

I8A-VET

New Member
Mar 24, 2018
8
0
1
50
I would get the alternator tested since you think it’s a problem, but I would do the wiggle test while the car is running. Just shake and wiggle every connector and wire to a sensor. I’ve had these problems before with Honda’s and specifically our new type R’s, the under hood fuse box had bad internal sauder welds/cracked welds and would cause the cars to cut out under load and stall or throw all the lights on. But those problems took days on days and mutlipe techs to figure it out. It was a lot of wire tracing and schematic work to track it down to the fuse box.

Also you said the car is a salvage, every time some thing stupid happens that isn’t common that for me 9/10 times it’s a ground. Usually they paint the car and put the grounds right back on top of the paint and you’ll have high resistance, if you have high resistance power won’t go back and it’ll find another path back to the battery and power other sensors and cause weird problems. I would remove all the grounds, file the surfaces that they go to, and reinstall and see if that helps. That’s been my number 1 cause of problems with every salvaged car I’ve ever had to diagnose.
Happy 2019. Still having these problems however now worse which is good. It's happening when I hit bumps. I say good since it has become evident that this is a ground issue just as you suspected. My question to you is, do you know the locations of all of the grounds on an 07 Shelby GT500? I wouldn't be surprised if the rebuilder neglected to reattach every ground connection. By the way, only one ride this far this year. When I got home I felt my battery cables and my ground was super hot!
 

I8A-VET

New Member
Mar 24, 2018
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Problem Solved! So I swapped the alternator with the J2 180 amp along with the Big 3 wire kit. The new alternator amplified the issue!! After about 10 hrs of testing and configuring things differently I started to mess with the data wires going into alternator connector. I de-loomed the wires, separated them and plugged it back in, problem solved!


Long story short I think the data telling the alternator how much output to produce was being corrupted from either being too close to the other wires, or just not making good enough contact.


Crazy! Now to begin worrying about breaking things as I put the power to the pavement!