ranchos

94 g.k. 200000 ml, v-8, alternator bench tested ok (puts out >15v) when hooked up in jeep puts out <12v, (previously removed 60pin wire connector to computer/cleaned/wiggled) no luck this time to get amp guage to indicate alternator is charging. what is the small black box on top of alternator? (activator?) were should i take voltage reading? and what volts should i see? can the black box be causing this?---any help appreciated (one of my kids college commute car)----thanks

OverlandZJ

I recently had an alternator that was occasionally not charging.. por low charge.

Remove the + batt cable as she's running. If it stalls replace the alt.

The black box would be the voltage regulator i believe.

trucker

The most common reason for failing the alt is the small wire going to alt. It get corroded or crack and do not supply "start-up" voltage to alt. I will start from there.

swarney1

try taking a wire hook it up to the back of altenator and run it to the battery. This will bypass all wiring, then check the voltage at the battery and the altenator. If the battery voltage matches the altenator then you could have a bad wire in there somewhere. Or just hook it up like that permatly.