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Dodge Repair/electrical voltage unstable


QUESTION: Head lights and interior lights dim and get brighter and battery gauge reads over the half way mark over time but rises at stop light.What could it be?

ANSWER: Hi Zack,
It may be that the alternator is in the process of "going", or possibly that there is some sort of an electrical short circuit/"drain" on the system. When you say "dim and get brighter" how does changing of the rpm of the engine correlate to the dimming/brightening?
The other possibilities are: that the battery is getting old. How long ago since it was bought? Or, if none of those are the cause then the voltage control of the alternator (done by the powertrain control module) is flakey.

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sitting at idle 600 rpm
sitting at idle 600 rp  
QUESTION: I can be driving and my lights will dim for a second or 2 then they will go back to normal,the rpm really don't effect it any,my battery is less than a year old duralast gold.

ANSWER: If the voltage gauge changes in synchrony with the brightness of the lights, then that suggests the voltage coming out of the alternator is not stable. That could be a sign that the alternator is wearing out, or possibly that the alternator field coil control wire from the alternator to the powertrain control module is flakey and thus causing the alternator to work/not work randomly. So look at the wires you find at the alternator to see if any of those look damaged and if not then I would suspect the alternator itself is going 'out'. If you write back tell me the year/model/body style of the vehicle.

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QUESTION: There is a blue/white wire coming off the top of the alternator that goes from the alternator to the pcm wire harness that I don't know what it belongs to. But 2006 dodge ram 1500 5.7 hemi

Hi Zack,
Is the 5.7L called an SRT-10 or not?
My '06 manual for the Ram doesn't show a blue/white wire at the alternator but rather three possible wires: one is thin brown/gray that go to the pcm, and then a thin brown/dark green or brown/black depending upon whether it is a regular Ram or an SRT Ram model which go either the pcm or to ground, and finally a thicker wire that is either light blue or brown/red that goes to the battery + post. So how thick is the blue/white wire and are you saying it is not connected to anything?

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Roland Finston


Get a Free Fast answer to your repair question about a Chrysler/Dodge/Plymouth car, minivan, SUV, or truck. Problems with electronically controlled engines and transmissions as well as body wiring problems are my specialty. This free troubleshoot advice forum helps you diagnose faults, minimize repair costs or do-it-yourself.

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I have do-it-yourself experience (50+ years) and a library of 100 1982-2012 Chrysler factory shop manuals and 20 multi-manual Chrysler Corp. CD's.

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