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Doctor D
Doctor D, Auto Service Technician
Category: Ford
Satisfied Customers: 763
Experience:  ASE Master, 20 Years Experience,
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My battery light kept coming..lights would dim when it one

Resolved Question:

My battery light kept coming on and off and the lights would dim when it came on. Took altenator in and had checked and everything tested fine. But I bought a new one anyway. Installed the new one and the battery light would come on when I accelerated then go off. That lasted two weeks and now it's back to off and on consistently. I drove 75 miles yesterday with it on the whole time and it dimmed my headlights but didn't drain my battery. And went off at real low rpms. Any clues
Submitted: 5 years ago via
Category: Ford
Expert:  Doctor D replied 5 years ago.

Doctor D :


Doctor D :

I've had LOTS of problems with aftermarket Alternators on Fords. So much so that i will not even install them any more. I only use genuine Motorcraft Alternators. I know thats not what you might want to hear, but please install a Ford Motorcraft Alternator and watch your problem be fixed :)

I don't now what engine you have but a 4.6 takes GL497RM

Doctor D :

5.4L GL508RM

And Amazon has great deals on Motorcraft parts by the way

Doctor D :

Amazon link

Customer: The original one I took out that tested good at Napa was a Motorcraft. It tested good so I put it back in. Problem kept up. Everybody I talked to said it was still altenator so I replaced it with new one. Problem quit for a coue weeks other than spiking on the voltage gauge at 3200+ rpm till let off gas. Then started right back the way it was in the beginning.
Customer: It had the original Motorcraft I'm it that napa tested good when all these problems started. It tested good so I put it back in and light kept on and slow drainage of the battery continued. Everybody said the same thing that it has to be the altenator so I bought a new one. Problem went away for two weeks other than voltage gauge spiking at 3200+ rpm untill let of gas. Then after two weeks right back where I started.
Expert:  Doctor D replied 5 years ago.
Can I get the engine and 8th digit of your vin so I can pull a schematic?
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