This afternoon, I performed the famous Electric Fan Conversion on a '91 Volvo 240. I tested the car, at idle, and everything worked OK. I drove the car 15 minutes to a friend's house, and it was running fine. The car sat for 1 hour. When I cranked the engine to return home, the CHECK ENGINE light came on! Now it will not go off! All electrical connections are OK, radiator is not leaking, fan is working, coolant temp guage is OK, other fluid levels are normal, no broken wires visible. Any suggestions??? What gives???

Here are the details of the Electric Fan conversion:
- CAR: 1991 Volvo 240, B230F engine, 109k miles
- REMOVED: loosened the alternator/water pump belt; unbolted the fan shroud; unbolted and removed the Volvo primary fan/clutch assembly; removed front grill and removed a broken auxiliary fan.
- ADDED: AC DELCO primary electric fan assembly from Pontiac Grand Am ($20); drilled screw holes in shroud; mounted fan to radiator; wired positive to Ignition Coil +15V post (terminal hot when ignition is ON); wired negative to good ground bolt in engine bay. No fuse added yet.

What could cause the CHECK ENGINE light to come on after driving 15 minutes? An electical problem? Loose belts? How dangerous is it to drive this car tomorrow?

Also, do I need to add a fuse or relay? What type? What advantage does a relay switch have over an small in-line fuse?

[[ southern fried volvo ]]