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 for more than 2.7 seconds. One Trip Fault. Three good trips to turn off the MIL.

POSSIBLE CAUSES
- Internal (A16) fused B+ circuit
- Internal (F1) fused ignition switch output circuit
- (N201) Cooling fan no.1 relay control circuit open
- (N201) 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. LOW SPEED RADIATOR FAN RELAY OPERATION
Ignition on, engine not running.
With a scan tool, actuate the Low Speed Radiator Fan Relay.

Q: Is the Cooling Fan Relay operating?

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

2. (A16) FUSED B+ CIRCUIT




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

Q: Does the test light illuminate brightly?

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

3. (F1) FUSED IGNITION SWITCH OUTPUT CIRCUIT




Ignition on, engine not running.
Using a 12-volt test light connected to ground, probe the (F1) Fused
Ignition Switch Output circuit.

Q: Does the test light illuminate brightly?

YES: Go To 4
NO: Repair the open or short to ground in the (F1) Fused Ignition Output circuit. Inspect the related fuse and repair as necessary.
Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test

4. LOW SPEED RADIATOR FAN RELAY RESISTANCE
Turn the ignition off.
Measure the resistance of the Low Speed Radiator Fan Relay Coil.

Q: Is the resistance between 60 to 80 ohms?

YES: Go To 5
NO: Replace the Low Speed Radiator Fan Relay.
Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test

5. (N201) 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 (N201) 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 6
NO: Repair the open in the (N201) Cooing Fan No.1 Relay Control circuit.
Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test

6. (N201) COOLING FAN NO.1 CONTROL CIRCUIT SHORTED TO GROUND




Measure the resistance between ground and the (N201) 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 (N201) Cooling Fan No.1 Relay Control circuit.
Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
NO: Go To 7

7. 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 Powertrain Control Module.
Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test