Alternator/ Voltage Regulator

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Dec 5, 2013 | 05:32 PM

Namu Mac

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Joined: Oct 2008

Posts: 15

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Model: Cherokee

Alternator/ Voltage Regulator

I have a 91 Cherokee w/ 4.0L. I getting an intermitent Alt. idiot light. I would suspect the regulator. Question is. Is the reg internal in the alternator or is it in the computer?

Dec 5, 2013 | 05:38 PM

PocketsEmpty

CF Veteran

Joined: Dec 2012

Posts: 4,169

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From: York, PA

Year: 1998

Model: Cherokee

Engine: 4.0

Quote:

Originally Posted by Namu Mac

I have a 91 Cherokee w/ 4.0L. I getting an intermitent Alt. idiot light. I would suspect the regulator. Question is. Is the reg internal in the alternator or is it in the computer?

It is in the computer. May want to get your alternator checked. Also a point of interest could be the battery temperature sensor located in the battery tray underneath of the battery. I'm not sure if the 1991 models have that.

Dec 5, 2013 | 08:33 PM

5-90

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Joined: May 2008

Posts: 3,018

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Year: 1988

Model: Cherokee

Engine: AMC242

1991 used the Nippondenso alternator, which is externally regulated. Regulator circuit is integral to the PCM.

Fortunately, failure is rather rare - check wiring and remove alternator for test at a local shop (not a parts house - those benches are worthless. Take it in the a dedicated alternator/starter house.)

The battery temperature sensor appeared in 1996, with OBD-II.