NR8 wrote:ever checked or changed the thermostat switch?
isn't the coolant temperature sensor the thermostat switch? thats what i always thought
nope...if you unplugged something and the fan came on, then you unplugged the fan switch - it goes to open circuit when a particular threshold temperature is achieved
your coolant temperature sensor is something completely different - it communicates with the ECU, not the fan circuit
The fact that the fan came on when you unplugged it suggests to me that the circuit is fine and either the switch itself or the fan may be at fault...or you're not letting it warm up enough.
How did you determine that it's not working? When you start up and just let it idle, it takes a long while to come on. Mine takes in excess of half hour to get up to normal operating temperature if it's just sitting there idling.