GM/Detroit 6.5L – AUXILIARY COOLING FAN REPLACEMENT

The auxiliary cooling fan provides additional cooling for low-speed vehicle operations, extended idle, stop-and-go conditions, and running the air conditioning system.

The auxiliary cooling fan circuit consists of a coolant temperature sensor, relay, and auxiliary fan. When the coolant sensor reaches a predetermined temperature, it closes the circuit to the relay coil. This energizes the relay, applying 12 volts to the auxiliary fan. When the coolant temperature decreases below the setpoint of the sensor, the circuit to the relay opens and voltage is no longer applied to the auxiliary fan. The cooling fan only operates when the ignition is on and the coolant temperature sensor is above the set temperature.

Refer to figure 15 for the auxiliary cooling fan circuit diagram, and figure 16 for auxiliary cooling fan system diagnosis.

FAN RELAY
Remove or Disconnect
1. Negative battery cable. Refer to SECTION OA.
2. Wiring harness connector.
3. Fan relay.

Install or Connect
1. Fan relay.
2. Wiring harness connector.
3. Negative battery cable. Refer to SECTION OA.

ENGINE COOLANT TEMPERATURE SENSOR
Remove or Disconnect (Figure 17)
1. Negative battery cable. Refer to SECTION OA.
2. Wiring harness connector.
3. Engine coolant temperature sensor.

Install or Connect (Figure 17)
1. Engine coolant temperature sensor.

Tighten
• Engine coolant temperature sensor to 23 N-m (17 Ibs. ft.).
2. Wiring harness connector.
3. Negative battery cable. Refer to SECTION OA.

 

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