Chrysler Repair: diagnostic fault code 41, inner fender, plymouth acclaim

Question
Thank you Roland

So, if that is the case if the alternator is replaced would that fix the problem? or does something need to be done with the coils.  I don't want to buy an alternator if that is not going to fix the problem.

The car stopped running on me this Saturday and the mechanic that helped said it was the alternator.  The check engine light came on several weeks ago and a friend did the ignition switch diagnostic to determine the diagnostic code which was 41.  

Thanks again for your prompt response.

S
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Followup To

Question -
what is diagnostic code 41 for 93 plymouth acclaim

Answer -
Hi S,
The 41 code means that there is some flaw in the circuit for the field coils of the altenator that probably also means that the alternator is not putting out voltage or current necessary to keep the battery charged. For the alternator to put out current and voltage there must be an electical voltage applied across the field coils. If not it would cause the battery to run down over time. It is fairly simple to verify if it is wiring or the field coils themselves that are at fault:
If you go to the alternator and find  the dark blue wire you should be able to measure (using a voltmeter or neon glow light placed between that wire and the engine block) 12v at the dark blue wire for about 1 second after you turn the ignition key to the run position, and after you start the car the 12V should be there all the time. The dark green wire should be connected to pin 20 of the 60-pin plug on the engine controller that is mounted on inner fender shield on the left side. If those connections seem to be o.k. then I would remove those two wires from the alternator and measure for continuity (using an ohmmeter = 0 ohms) between the two posts that held those wires onto the alternator. If there is no continuity (infinity ohms) then there is an internal break in the field coil of the alternator which prevents it from creating the electric field so you you have to replace the alternator. The charging light would likely be 'on' when the car is running under these conditions.
Roland

Answer
Hi S,
The field coil is internal to the alternator so a rebuilt alternator will mean a changeout of the field coil. I mentioned the other possibility, that there is an open in one of the two wires that connect the field coil to the control circuit, for completeness. The chances are 90% that replacing the alternator will fix it, but if you have a friend with a meter you could do the wiring checks so as to avoid disappointment and expense on the outside chance that it is not the field coil that is the cause of the non-function.
Roland