Charging Issue caused by Faulty IDM

zankof

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I appoligize in advance, this could get kinda long.

OKay, so about a month ago I was in a 5 car accident (not my fault) and I got damage on both ends of my truck. (which I guess I should say is a 2003 f350 7.3l)

2 days later, my alternator died. Fine, didn't think anything of it. Replaced it, instantly started reading 14.6 volts.

2 days after this, my alternator starts jumping all over the place, reading low in the morning, then jumping way up and going over 15.9 V (not sure exactly how high it is going because that is as high as my AIC reads volts). When it does this the dash turns off, the gauges go dead, the radio turns off, the windows don't work, but the engine runs fine. Back off a little, the volts come back down, everything turns back on. It did this 16 times in 30 minutes while I was on my way to the parts store to get it replaced. I had thought that it was the alternator, so I replaced it. I had the batteries tested just to be sure and they both checked out fine.

all was well for about a week, then it started doing the crazy high voltage again. turned everything off and back on 6 times in 6 blocks. So I dig out the volt meter and start checking things. find that the voltage sensing wire is reading exactly what the batteries are reading. check resistance on all the wires connecting the batteries to the alternator, all good. Pulled everything apart and cleaned all the connections really good and put it back together. Now it seems to be running right, but the battery light on the dash won't go out.

Anyways, fast forward to this week, finally get my truck into the body shop. I have them have a look at this because I can't figure out what is wrong and I am sure it is related to the accident. I get a call today saying that my Check engine light was on because of having a faulty IDM. I ask him if he means the battery light, and he says, while the light that was on.

So after all that, here is my question, has anybody heard of a Fault IDM causing the battery light to be on?

Second, anybody have any idea what might be causing my issues?
 

F350-6

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... finally get my truck into the body shop. I have them have a look at this because I can't figure out what is wrong

I don't know of too many body shops I would trust to diagnose an IDM issue.


So after all that, here is my question, has anybody heard of a Fault IDM causing the battery light to be on?

No.

Second, anybody have any idea what might be causing my issues?

I'd guess because you went back to the same store and got another alternator from the same batch as the first bad one. If you're checking voltage at the alternator itself and getting the high readings, it's just time for another new alternator. The 2nd to last "lifetime" alternator I put in my truck didn't make it 2 miles before the battery light came on again.
 

zankof

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I don't know of too many body shops I would trust to diagnose an IDM issue.




No.



I'd guess because you went back to the same store and got another alternator from the same batch as the first bad one. If you're checking voltage at the alternator itself and getting the high readings, it's just time for another new alternator. The 2nd to last "lifetime" alternator I put in my truck didn't make it 2 miles before the battery light came on again.

Body shop and mechanics are attached in same building.

and the alternator came from two different stores (both autovalue) in the same city.
 

F350-6

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Body shop and mechanics are attached in same building.

and the alternator came from two different stores (both autovalue) in the same city.

OK, so how did they determine the IDM was at fault? Did they get a P1316 code and assume the IDM had to be replaced? IDM codes mean there is an issue with injector solenoids or wiring between the PCM - IDM - Injectors.

IDM codes also throw a CEL, not just a battery light. I don't think your alternator issues are related to the IDM.
 

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