1992 4JB1T Charging Issue

[IsuzuCamper]

1992 Isuzu Rodeo Camper Turbo Diesel. I'm getting only 12.25 at the most when at idle at the battery. Changed the grounds and and other cables possible. Tested the Charging relay (BLue) tested good but ordered another. I pulled the alternator to get tested tomorrow from a shop that is familiar with that type if Isuzu Alternator with the vacuum pump. Any thing else I should be looking at? Been working on 7.3's and Cumins for years, This is a new one. Happy to learn.

Cheers Mates,

Patrick

Boulder Colorado

[geeves]

Unless the battery is completly charged that reading at idle isnt wrong. Test it at at least 1500 rpm. Below that the losses in the battery prevent it showing full voltage. Otherwise the regulator, diode pack or stator coils might be faulty.
I trust you have verified your multimeter is correct?

[IsuzuCamper]

Thanks Geeves for the quick reply. Yes. I tested 2 other vehicles with the multi-meter. Both were charging correctly and multi-meter was working. I tried to drive it at night and the light dies and was losing power. Something isn't right. Hopefully the alternator test gives me a start tomorrow. I'll be posting back right away. Otherwise, it drives so good. Runs smooth. No smoke. Very happy once I get this fixed.

Cheers

Patrick

[IsuzuCamper]

Pulled the alternator this morning and got it tested. Alternator is good. All connections coming out of the alternator test good. So moving on up the ladder. Next the connection and wire feeding the main power distributor. Any thing else I should check?

Cheers,

Patrick

[IsuzuCamper]

After some more internet research, I found some information on the connection from the ignition to the alternator. "idiot light" I've heard of it but never had to diagnose it. I'll post back if this is it. I hope so.

[PhilthyPhil]

I have a similar issue now too :/ My alternator is charging but only when you rev it up to 2 minimum, when the revs drop to idol, my engine/fuel and some other light pops up. Fully charged the battery so that eliminated it but it draining the battery and not getting good charge basically.
Happened after a trip to Muriwhai Beach...hmmm
Swapped the charge relay with the relay for the headlights which is the same it seems and that didn't fix it.
Gave the alternator a good clean and crc as I thought maybe some shit in there...didn't fix it so far.
Next looking at the earth wires.
Someone mentioned hard wiring it using jumper cables direct to the battery just to see if it charging and potentially eliminate bad connections / earth?

Probably an alternator out situ now im thinking..

[geeves]

Water normally dries but muddy or salty water can leave crud on the slip rings causing bad charge. It can also cause the brushes to sick. Salt can also short the regulator and diodes. Alterator apart and clean should fix