1999 Dodge Grand Caravan charging system fluxuation

DAVIDBURDICK4

MEMBER
1999 DODGE CARAVAN
6 CYL
2WD

My battery light comes and goes, the battery is not getting properly charged. It is losing power. I had the system tested 5 times. I cleaned the connectors and terminals and replaced the battery. I had the Alternator checked, all this is good. Yet I still get a power drop and my battery is getting drained? Any ideas?

5 Replies

DOCFIXIT

MECHANIC
18,828 POSTS

PCM controls field circuit as to output so PCM maybe faulty. Check engine light on? Has PCM been checked for codes?

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Thursday, January 13th, 2011 AT 5:12 PM

DAVIDBURDICK4

MEMBER
3 POSTS

No they only tested the system. The check engine light is not on. Only the battery light.

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Thursday, January 13th, 2011 AT 5:36 PM

CARADIODOC

MECHANIC
33,864 POSTS

Common too for brushes to be worn and intermittent. On many Chrysler products they can be replaced without removing the alternator from the engine. Any testing has to be done while the problem is occurring. No problem will be found when the system is working because no problem exists at that time.

(Hi Docfixit)
caradiodoc

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Thursday, January 13th, 2011 AT 5:44 PM

DAVIDBURDICK4

MEMBER
3 POSTS

Ok on that model, is there more than one PCM? And where is it located? Also which one is responsible for the alternator?

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Thursday, January 13th, 2011 AT 5:59 PM

CARADIODOC

MECHANIC
33,864 POSTS

Engine computer is the Powertrain Control Module. It has the voltage regulator built in.

When the problem acts up, measure the voltages on the two small terminals on the back of the alternator. They could be two plugged-in wires or two small nuts next to a black plastic block. One of those will have full battery voltage when the engine is running. The secret to diagnosing this system is the voltage on the other nut. If it is 0 volts, the brushes are open. If it is the same as the first terminal, the voltage regulator in the PM could be bad but more likely the wire going to it is open. If that part of the system is working the voltage will be less than the first terminal.

Caradiodoc