Without A/C

When ECT temperature is less than 212°F (100°C), all relays and fan is off. When ECT temperature is 212-226°F (100-108°C), relay No. 1 is on and fan is on low speed. When ECT temperature is more than 226°F (108°C), all relays are on and fan is on high speed.

Ensure engine is at ambient temperature. Connect scan tool. Turn ignition on. Select PID/DATA MONITOR AND RECORD function. Select A/C SW, A/CP SW and ECT PIDs. Start engine. Monitor all PIDs and cooling fan operation under following conditions:

1. If ECT is less than 212°F (100°C) fan should be off. If fan is on, check the following:
   • Short to ground on Green/Black wire or Blue/Orange wire between relay No. 1 and PCM terminal No. 12.
   • Short to ground on Yellow/Red wire or Green/Black wire between relay No. 2, relay No. 3 and PCM terminal No. 45.
   • Relay No. 1, relay No. 2 or relay No. 3 contacts stuck closed.
   • Short to power on Black/Yellow wire between relay No. 1, relay No. 2 and fan motor.
2. If fan motor does not operate, check the motor.
3. If fan motor low speed is okay, but high speed does not operate, check the following:
   • Open power circuit for relay No. 2 or relay No. 3.
   • Fan relay No. 2 or relay No. 3 contacts stuck open.
   • Faulty fan motor.
   • Open circuit on White/Red wire between relay No. 2 and fan motor.
   • Open circuit on White/Green wire between fan motor and relay No. 3.
   • Open circuit on Black wire between relay No. 3 and ground.
   • Open circuit on Yellow/Red wire between relay No. 2, relay No. 3 and PCM terminal No. 45.
4. If fan motor high speed is okay, but low speed does not operate, check the following:
   • Relay No. 1 contacts stuck open.
   • Open circuit on Black/Yellow wire between relay No. 1 and fan motor.
   • Faulty fan motor.
   • Open circuit on Black wire between fan motor No. 1 and ground.