Disconnect the electrical connector at the fan and run 12volts directly to the fan. If it runs at least you know it is good.
The cooling fan is protected by a 25 amp fuse. Is it OK
The radiator fan temperature switch (closing temperature)...... 199 +/-5 F
Engine coolant temperature light switch(closing temperature)....232 +/- 5 F
The radiator fan is switched via a relay.
There are two coolant switches. One for fan and the other is for the dash light.
1. Are you getting 12 volts at the coolant sensor when above its trip point? If yes the coolant sensor is OK
2. Is there 12 volts on the red relay supply wire from the fuse block? If yes, fuse is OK. If no, check the 25 amp fuse or corrosion at the fuse block.
3. Is there 12 volts at the red fan supply wire when engine is above trip point? If yes fan motor is suspect. If no and the other two above are ok, likely to be the relay.
2012 JD855D OPS Black Poly Roof, Deluxe Cargo Box, Front and Rear Protection, Power Lift, Front Hood Rack, Rear Screen (homemade), 800 Watt Inverter, 2500lb Winch installed in cargo bed, Front and Rear LED auxiliary lighting (4" square 27 watt), Front and Rear CV Guards, Koplin Side Mirrors
Last edited by 200mph; 11-19-2016 at 03:23 PM.
Reason: Added detail