hot-J

The altenator on the car is not charging. Exciter wire had power when in the on position, and goes up when cranking, and no power in the off position. grounds are clean via die grinder....... Tried a altenator I had on the shelf with about 500 mi on it, and same results. The car is an 86, has no alarm, but the factory jumper plug in place where the alarm box should be, so thats good. I am quickly running out of ideas. BTW batt is new.

Ronin-951

Since you've tried a different, thought to be good Alternator, you should run the other Alt. by a Part Store for a check. For free, I'd hit the Grounds on the Block, Firewall and at the Battery, and the Positive main line from the Alt. at the Starter.

hot-J

Going to autozone in a minute with the low mi one, starter wires were cleaned up last week, and I did take a peek... they look fine. the car runs, so the main ground is unlikely the suspect, but ill try it. This one has seriously got me stumped.

hot-J

ALT is good, this one I really need help with. How much voltage is suppose to be at D+ aka the little blue wire?

Ronin-951

Battery Voltage [slightly under] on the Exciter Wire. Since the Alt. checked out, can ONLY be Wire or Connections. BTW, sometimes the output leaves a bit to be desired till the RPM's reach 1500, a blip of the Throttle at first start-up will generaly get things going.

hot-J

Ok, I think I was getting 0.9 to 1.5v......... Time to double check that.

hot-J

I have 12v at exciter wire with the car running, and 11.85 at B+ wire. Now what?

Ronin-951

Check the Output Wire [big one] at the Alternator, should be 14.2 - 14.5 volts with the Engine running. My thought is that your wire's are corroded and the connections are fowl, - not so much at the Alternator, but somewhere in route to the Battery. Two sides to every story, so check both the Positive and Negative path with an Ohm Meter and Engine off, 0 ohm's is what to strive for.

hot-J

Ughhhh its charging. All connections are clean, I noticed the big power wire to the battery is getting HOT. Could the starter be causing this? It started charging after I put a new ignition switch in, while under the dash the old one crumbled in my hands.

hot-J

I am not sure if the power wire is hot because the alt is basicly charging the dead batt, or there is resistance inbetween. I can say without a doubt the resistance, if its that is not corroded connections.

Ronin-951

Wire itself can increase in resistance, use the Ohm Meter, 0 is unattainable, but should be 1 Ohm or less. And yes, a battery that has 12 volts can still be faulty, a 'Load Test' is what to use for the Battery check, - free test at most Part Stores, or HF has test units for cheap. Batteries generally only last 5 years, borrowed time after that.

hot-J

Found some of those smaller power wires near the terminal frayed and most likely shorting. Hopefilly this will solve most of the issues. Thank you for your help!