RacerDave
Expert
Overheat light came on from low snow conditions. Fan would not come on. Shouldn't the cooling fan come on before or with the over heat light? The fan will work by pulling the relay and jumping the correct terminals. The relay works fine on a bench test. Does the temp switch trigger the fan relay through the ecm? Is this temp switch normally open till it reachs xx temp and then the relay gets closed turning on fan, or does the temp switch have a variable resistor sending a signal to the ecm and then the ecm triggers the fan relay at xx temp?