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Chris, Shop Foreman
Category: Jeep
Satisfied Customers: 3379
Experience:  Jeep Certified Master Tech
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What can I troubleshoot if I have a second alternator that

Customer Question

What can I troubleshoot if I have a second alternator that appears not to be charging the battery, what loose fuses and other connection issues can I troubleshoot? Have a battery charger and have charged battery in car fully, all is fine on that end. Not getting any increase beyond 12v at battery from alternator when car is on, simply draining battery when car is running then check engine light comes on. This is a 1991 (YJ) with a 4.0l (straight 6), manual 5 speed (presume AX15) transmission.Any easy way to check for partial grounds or partial connections without going through hours of detail, maybe checking individual circuits?
Submitted: 1 year ago.
Category: Jeep
Expert:  Chris replied 1 year ago.

Hello and welcome to just answer. This may be a problem with the PCM because it is responsible for regulating the charging system voltage. The PCM is the engine computer. The other thing that it may be is a broken fuse link between the alternator and the battery. Let's check that first. With the engine off, measure the voltage at the large alternator post. It should be the same as the battery. Let me know what you find.