Installing '10 GT alternator in '06 GT: How to connect? Please help

good luck

 

I don’t remember my 07 gt having a light for the headlights only for the high beams.

I’d guess it’s that ecu plug, check it again to make sure it’s fully seated.


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Your alternator needs the following to work: 1) A ground - typically it comes from being bolted to the engine but I had to add another from the passenger strut ground to a bolt on the alternator to get a good ground. Since yours worked initially I would say your ground is okay but easy to do a continuity check from the that ground to a bolt on the alternator. You should see less than a ohm. 2) B+ cable from the alternator bolt on the back that recharges the battery through the fuseable link. 3) PCM sense lines (Gen Mon; Gen Com; PCM plug pins 1,2) from the ECU that control the alternator output. Pin 3 goes to F43/10A fuse in the BEC fuse box.

Here's a link to the online manual for electrical wiring and connections for the charging system: http://iihs.net/fsm/?d=40&f=Charging System.pdf

99 times out of a 100 it's something you changed, connected, disconnected, damaged taking it off or reinstalling or what have you. Suggest rechecking your work concentrating on the connections at the back of the alternator (cut and extend that PCM plug if you have to) and make damn sure nothing is even close to the alternator output.

If you have a VOM do continuity checks on the PCM plug from end to end and check for shorts between wires in the plug. (you can buy a replacement (plug w/pigtail) for ~$10 online if needed). If you find any issues strip away the tape as needed and repair.

If you shorted something in the alternator it may be gone. Take the alternator off and find an alternator rebuilder. They're the only ones I would trust to tell you whether it's still working correctly or not. I had two auto stores and a dealer mechanic all tell me my very expensive DOB alternator was bad while a rebuilder told me it was fine. It ended up being fine and I'm still using it today. My grounds were bad...thus the reason I always check grounds when troubleshooting electrical issues.

 

I agree with having an alternator shop do the testing... (not just an auto parts store) And definitely use a alternator-specific shop for a rebuild. Most states have a good shop, but in case anyone is looking for a good one I've used these guys a bunch of times... https://g.co/kgs/uSnrud

It does sound like the OP may have pinched a wire, popped a fuse etc. etc. If the OP is going to cut and lengthen the wires use solder, heat shrink, and the same size and quality of wire.

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Recently my battery kept dying overnight in my 09 p71. Right before it was decommissioned the agency put a new intake and Ford alternator on it. It was great until a couple months ago I’d go outside to start it and it’d be completely dead. I charged the battery and all was well until it sat over night. It could sit all day no problem. I had a good used alternator sitting in my garage I swapped in and no more issues.

Moral of the story, just because it’s new doesn’t mean it works. Good thing it fixed itself.


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I bought a used alternator from LKQ for 60 bucks for a 2010 mustang. Put it on my 08 gt with no clocking just loosened up the wiring harness from its holders and it worked fine.


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Typ u will measure 12.2 to 12.5 vdc on the battery terminals. (eng off). With eng on, you should measure 14.5 to 14.75 vdc...right at the battery terminals. If you start the eng, and battery voltage is only 12.XX your alternator is DOA.

Assuming the alternator is good, and battery voltage measures 14.5 to 14.85 vdc ( eng on), switch the DVM to read AC volts. It should read zero or close to zero. If it reads any amount of AC voltage, you have AC ripple coming out of the alternator.... which means one or more of the six diodes is toast.

 

I've had alternators bad out of the box. Last time Ford changed mine I had to wait an extra day while they got a replacement for the replacement.