Test D: The Cooling Fans Are Inoperative

Pinpoint Test D: The Cooling Fans Are Inoperative

Normal Operation
Low speed operation: Voltage is supplied to the cooling fan relay coils through circuit 361 (RD). The PCM grounds the low and high speed cooling fan relay coils through circuit 639 (LG/VT). The PCM grounds the engine cooling fan relay coil through circuit 232 (LG/YE) and the cooling fan brake relay coil through circuit 386 (LB). Voltage is provided to the cooling fan brake relay switch through circuit 225 (DB). When the cooling fan brake relay is energized, voltage is sent to the cooling fan relay switch through circuit 3850 (LG/VT). When the cooling fan relay is energized, voltage is sent to the LH cooling fan motor through circuit 229 (RD/OG). Voltage is sent from the LH cooling fan motor to the high speed fan relay switch through circuit 57 (BK). When the high speed fan relay is energized, voltage is sent to the RH cooling fan motor through circuit 228 (DB). The RH cooling fan motor is grounded through circuit 57 (BK).

Medium speed operation: Voltage is supplied to the cooling fan relay coils through circuit 361 (RD). The PCM grounds the cooling fan brake relay coil through circuit 386 (LB). When the cooling fan brake relay is energized, voltage is sent to the engine cooling fan relay through circuit 3850 (LG/VT) and then to the cooling fan resistor through circuit 228 (DB). The voltage is sent from the cooling fan resistor to the cooling fan motor and the low speed fan relay switch through circuit 229 (RD/OG). The LH cooling fan motor is grounded through the high speed fan relay and circuit 57 (BK). Voltage is sent from the low speed fan relay to the RH cooling fan motor through circuit 228 (DB). The RH cooling fan motor is grounded through circuit 57 (BK).

High speed operation: Voltage is supplied to the cooling fan relay coils through circuit 361 (RD). The PCM grounds the engine cooling fan relay coil through circuit 232 (LG/YE) and the cooling fan brake relay coil through circuit 386 (LB). When the cooling fan brake relay is energized, voltage is sent to the engine cooling fan relay through circuit 3850 (LG/VT). When the cooling fan relay is energized, voltage is sent to the LH cooling fan motor through circuit 229 (RD/OG). The LH cooling fan motor is grounded through the high speed fan relay and circuit 57 (BK). Voltage is sent from the low speed fan relay to the RH cooling fan motor through circuit 228 (DB). The RH cooling fan motor is grounded through circuit 57 (BK).

Possible causes
^ Open fuse
^ An open in circuit 228 (DB), 3850 (LG/VT), 229 (RD/OG) or 57 (BK)
^ Fan braking relay
^ HEDF relay
^ Resistor relay
^ EDF relay
^ Cooling fan(s)

D1:

D2-D5:

D5-D8:

D8-D11:

D11-D13:

D14-D16: