Hi,
i'm Alessandro from Italy, i have the nth problem with my XJ 4.0 89' (Renix powered)...
Some days ago the alternator was overcharging the battery, until it wind out the acid...i was tripping to home from work and scared to the battery explosion i disconnected the battery at started engine, to continue the travel without charging... but after some km the engine shut down because the alternator don't work anymore.

Now i have replaced the delco alternator with an used one but it don't want charge anymore the battery....anyone can help me on what i have to check?

Best regards

Are you sure used ones good ? Try installing another battery ...

Maybe the battery went out of acid as you mentioned.

How's the connector plug at the alternator? Do you have a meter to test voltage with?

I have already change the battery because the old one was damaged by the high voltage, and yes i have the meter to test the voltage, i know that there is a +12V under key that have to eccitate the alternator to make it working, anybody know if this +12V is protected by any fuse? I have tried to check in the fuse box diagram but i don't find it. Tomorrow i'll try to check if this +12V is on the alternator wire by the meter...

Red wire is battery voltage. There is a fusible link in that circuit.

Yellow wire is voltage from ignition switch ON.