Here is the problem guys. The last owner of my car grounded the fan to the frame with a relay so that the fan would go on when the car is started. I have no idea why he did this. I thought maybe there was something wrong with the computer and was too cheap to fix it. Today I bought a new PROM. I installed it and now the fan won't run with the new PROM in there. The fan will go on for a couple of seconds when I start it, but thats it. I know there is not anything wrong with the fan itself, because it works when i put the old PROM back in. Does anyone know if the fan has anything to do with the computer and why would someone ground it like that. Please let me know how to fix this problem also. Thank you.

 

The fan relay is part of the stock setup. Many guys ground the fan relay to keep the fan on all the time which is a waste of time and energy. The fan on your setup should kick in about 220-230 degrees. The fan according to my schematics is controlled by the ECM or computer. To test the fan operation put in a jumper like you would do to get trouble codes, then turn on the key but do not start the engine. The fan should come on and run, that tells you the computer, the fan relay and everything is OK. Also turning on the AC should also kick it on. If is turning on momentarily then it is probably OK as far as wiring is concerned. As I said it will not turn on until the engine reaches about 225 degrees, so be careful and let it idle and get hot. It should kick on a little past the halfway point on the temp guage. Many people try to fix problems with the cooling system by keeping the fan on all the time, however it's just a band-aid fix. Make sure the cooling system is properly serviced and good coolant is in it and you should be OK with the fan control returned to the computer.