by isuzurob » Sun Nov 15, 2015 6:51 am
I just had the same fualt in my 89 bighorn, and that is a complex system, best way is to find a wiring diagram, mine has 2 inline fuses by the steering colum, a resister in the heater box and 4 relays the charge relay is one of them, then to a relay behind passenger headlamp the is earthed by the oil pressure sensor on the engine (this relay was faulty on mine) have ac and blower fan again, then i had a high speed relay and mid speed, The systm works on constant power to the fan and resists the earth for fan speeds, well thats how mine was