ISB/ISBe Series Engines – 019-045   Fan Control Circuit

The electronic control system can control the fan clutch activation. The ECM can send 12 VDC or 0 VDC to energize the fan clutch or air valve solenoid.

Refer to vehicle manufacturer’s publications for more information on troubleshooting and repair of the fan clutch’s wiring.

The fan clutch resides in the OEM harness. The circuit consists of the signal from pin 5 of the OEM harness connector to pin 1 of the 2-pin Weather-Pack connector, and return from pin 2 of the 2-pin Weather-Pack connector to pin 10 of the OEM harness connector.

CAUTION  To reduce the possibility of damage to the connector pins, do not use probes or leads other than Part Numbers 3164112 and 3823995. The leads must fit tightly in the connector without expanding the pins of the connector.

Check the OEM harness to the fan clutch solenoid for an open circuit. Disconnect the 2-pin connector and OEM harness 89-pin connector.

Insert the appropriate test lead into pin 5 of the OEM harness connector, and attach the lead to the multimeter probe.

Insert the other appropriate test lead into pin 1 of the fan clutch solenoid connector, and attach it to the other multimeter probe. Measure the resistance. The multimeter

must show a closed circuit (10 ohms or less). If the circuit is closed, it

must still be checked for short circuits from pin to pin. If the circuit is

not closed, there is a connection problem or an open circuit in the wiring harness.

Insert the test lead into pin 10 of the OEM harness connector.

Insert the other test lead into pin 2 of the fan clutch solenoid connector.

Measure the resistance.

The multimeter

must show a closed circuit (10 ohms or less). If the circuit is

not closed, there is an open circuit in the OEM wiring to the fan clutch solenoid. Repair or replace the OEM harness. Refer to Procedure

019-323
or

019-071.

Check for a short circuit between pin 5 and all other pins in the OEM harness connector.

Insert the appropriate test lead into pin 10 of the OEM harness connector, and attach it to the multimeter probe. Insert the other appropriate test lead into all other pins of the OEM harness connector.

Measure the resistance.

The multimeter

must show an open circuit (more than 100k ohms).

If the circuit is

not open, there is a short circuit between pins 5 or 10 and any pin which measured a closed circuit.

Repair or replace the OEM harness. Refer to Procedure

019-323 or

019-071.

Connect the OEM harness 89-pin connector and the fan clutch solenoid after completing the repairs.