Charging problem

[Rande]

Guys, the alternator in my '80 J10 is not charging the battery. I run the engine and the ammeter shows a slight discharge. Rev the engine and it gets no better. Turn on the headlights and the discharge gets worse. Revving the engine doesn't help.

So, the alternator isn't doing its job. Swapped a good one from my friends Cherokee and still no worky.

Engine to chassis wire is good with good contact. I just swapped the engine and cleaned off the contact points for that wire. Alternator is hooked up properly. Belt is good, tight, alternator spins fine. Battery cables are good, battery posts and cable ends were cleaned. Little wire from negative battery cable to inner fender is good with good contact.

So, fusible link? Seems to me that is next to check. I don't know where this link is or how to recognize it if I saw it. Anyone have a charging system wiring diagram you could email me?

I brought the original alternator back home with me (the truck is at my friends farm, about 60 miles away) to have the local shop test it for me. I don't think the alternator itself is the trouble since we swapped in a known good one and it still won't work, but I thought I would have it checked out and possibly rebuilt anyway just for peace of mind.

[ March 23, 2003, 07:54 PM: Message edited by: Rande ]

[Rande]

Btt

[Brown Bear]

I'd take both alternator and battery to the shop and have both load tested. A bad batt. can give you the same symptoms as a bad alt.

[Rande]

Battery is good.

Basically, I need to know where that fusable link is. How to recognize it. How to test it. Where to get a replacement if its bad. Also, a scan of the wiring diagram would be helpful.

[Bob Barry]

It's a thicker piece of wire within the first foot or so of the charging wire running off the back of the alternator, or the yellow wire running off the starter solenoid.

Check for continuity between the charging wire and the (+) post on the starter relay. If it's not there, then trace it to the firewall bulkhead connector, then to the big-splice, and then to the back of the ammeter.

You'll find the break somewhere in there.