P0480

P0480-COOLING FAN 1 CONTROL CIRCUIT

P0480 - Cooling Fan 1 Control Circuit:

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
- (A16) Fused B+ circuits
- (K173) Cooling fan no.1 relay control circuit open
- (K173) Cooling fan no.1 relay control circuit shorted to ground
- LOW Speed radiator fan relay
- PCM

Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding.

Diagnostic Test

1. COOLING FAN RELAY OPERATION
Ignition on, engine not running.
With a scan tool, actuate the Cooling Fan Relay.

Q: Is the Cooling Fan Relay operating?

YES: Refer to the INTERMITTENT CONDITION Diagnostic Procedure. Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
NO: Go To 2

2. (A16) FUSED B+ CIRCUITS





Turn the ignition off.
Remove the Cooling Fan Relay.
Using a 12-volt test light connected to ground, probe the (A16) Fused B+ circuits.

Q: Does the test light illuminate brightly?

YES: Go To 3
NO: Repair the open or short to ground in the (A16) Fused B+ circuits. Inspect the related fuse and repair as necessary. Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test

3. COOLING FAN RELAY RESISTANCE
Measure the resistance of the Cooling Fan Relay Coil.

Q: Is the resistance between 60 to 80 ohms?

YES: Go To 4
NO: Replace the Cooling Fan Relay. Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test

4. (K173) COOLING FAN NO.1 CONTROL CIRCUIT OPEN





Disconnect the C3 PCM harness connector.

CAUTION: Do not probe the PCM harness connectors. Probing the PCM harness connectors will damage the PCM terminals resulting in poor terminal to pin connection. Install Miller Special Tool #8815 to perform diagnosis.

Measure the resistance of the (K173) Cooling Fan No.1 Relay Control circuit from the Relay to the appropriate terminal of special tool #8815.

Q: Is the resistance below 5.0 ohms?

YES: Go To 5
NO: Repair the open in the (K173) Cooing Fan No.1 Relay Control circuit. Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test

5. (K173) COOLING FAN NO.1 CONTROL CIRCUIT SHORTED TO GROUND





Measure the resistance between ground and the (K173) Cooling Fan No.1 Relay Control circuit at the Relay connection.

Q: Is the resistance below 100 ohms?

YES: Repair the short to ground in the (K173) Cooling Fan No.1 Relay Control circuit. Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
NO: Go To 6

6. PCM

NOTE: Before continuing, check the PCM 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.

Q: Were there any problems found?

YES: Repair as necessary. Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
NO: Replace and program the Powertrain Control Module per Service Information. Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test