I've got a 1986 Caravan with a 2.6L engine. The electric fan pressure/temperature sensor failed, causing the engine to overheat and blow a head gasket. After replacing the head gasket, and the sensor... The fan still does not come on. When the sensor is jumped out, the fan runs.

Any ideas on what could be causing this?

 

You must have got a bad sensor.Take that one back and get another one.You could try testing the new sensor by heating a pan of water and see if the sensorcompletes a circuit.An ohmmeter or test light will be needed to dothis test.