I thought I'd answer your question here, just 'cause it might help someone else. The alternator wiring looks to be this way:

Chassis/Alternator connector
Black-white/Black-white ... Ignition (might be black-yellow since it's very dirty)
White/White ... 12 V battery
White-Green/White-Red ... measures 86 ohms - charge relay

Hope that helps.
Is your relay and temperature switch a one-piece unit?


1991 Isuzu Bighorn LWB 2.8TD 4JB1-TC