2007 Commander XK Factory Service Manual 9 - ENGINE

P0480-COOLING FAN 1 CONTROL CIRCUIT

For a complete wiring diagram Refer to Section 8W.

When Monitored:
With the ignition on. Battery voltage greater than 10 volts.
Set Condition:
An open or shorted circuit is detected in the radiator fan relay control circuit. One Trip Fault. Three good trips to turn off the MIL.

Possible Causes

FUSED B+ CIRCUITS

RADIATOR FAN LOW RELAY CONTROL CIRCUIT OPEN

RADIATOR FAN LOW RELAY CONTROL CIRCUIT SHORTED TO GROUND

LOW SPEED RADIATOR FAN RELAY

FRONT CONTROL MODULE

Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING).

Diagnostic Test

1. LOW SPEED RADIATOR FAN RELAY OPERATION

NOTE: If the P0480 is setting on a 5.7L engine, Refer to P1646-HYDRAULIC COOLING FAN CONTROL CIRCUIT LOW diagnostics. (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING)

Ignition on, engine not running.
With a scan tool, actuate the Low Speed Radiator Fan Relay.

Is the Cooling Fan Relay operating?

Yes

Refer to the INTERMITTENT CONDITION Diagnostic Procedure.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)

No

Go To 2

2. FUSED B+ CIRCUITS

Turn the ignition off.
Remove the Low Speed Radiator Fan Relay.
Using a 12-volt test light connected to ground, probe the Fused B+ circuits.

Does the test light illuminate brightly?

Yes

Go To 3

No

Repair the open or short to ground in the Fused B+ circuits. Inspect the related fuse and repair as necessary.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)

3. LOW SPEED RADIATOR FAN RELAY RESISTANCE

Measure the resistance of the Low Speed Radiator Fan Relay Coil.

Is the resistance between 60 to 80 ohms?

Yes

Go To 4

No

Replace the Low Speed Radiator Fan Relay.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)

4. RADIATOR FAN LOW RELAY CONTROL CIRCUIT OPEN

Disconnect the C3 FCM harness connector.
Measure the resistance of the Radiator Fan Low Relay Control circuit from the Relay to the C3 FCM harness connector.

Is the resistance below 5.0 ohms?

Yes

Go To 5

No

Repair the open in the Radiator Fan Low Relay Control circuit.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)

5. RADIATOR FAN LOW RELAY CONTROL CIRCUIT SHORTED TO GROUND

Measure the resistance between ground and the Radiator Fan Low Relay Control circuit at the Relay connection.

Is the resistance below 100 ohms?

Yes

Repair the short to ground in the Radiator Fan Low Relay Control circuit.

Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)

No

Go To 6

6. FRONT CONTROL MODULE

NOTE: Before continuing, check the FCM harness connector terminals for corrosion, damage, or terminal push out. Repair as necessary.

Using the schematics as a guide, inspect the wire harness and connectors. Pay particular attention to all Power and Ground circuits.

Were there any problems found?

Yes

Repair as necessary.

Perform BODY VERIFICATION TEST. (Refer to 8 - ELECTRICAL/ELECTRONIC CONTROL MODULES - STANDARD PROCEDURE)

No

Replace Front Control Module per Service Information.
Perform BODY VERIFICATION TEST. (Refer to 8 - ELECTRICAL/ELECTRONIC CONTROL MODULES - STANDARD PROCEDURE)