Diagnostic Test
- COOLING FAN OPERATION (LOW SPEED)
- COOLING FAN OPERATION (HIGH SPEED)
- With a scan tool, actuate the cooling fans in high speed operation.NOTE:
During high speed actuation the Cooling Fan Motors are easily audible.
Are both Cooling Fan Motors operating?
Yes
- The Cooling Fan Motors are operating properly.
No, Cooling Fan Motor 1 is inoperative
- Go To Step 8
No, Cooling Fan Motor 2 is inoperative
- Go To Step 11
- With a scan tool, actuate the cooling fans in high speed operation.
- CHECK THE (A16) COOLING FAN 12 VOLT SUPPLY CIRCUIT
- Turn the ignition on.
- Remove the Hi-Med. Fan Relay.
- Using a 12-Volt test light connected to ground, probe the (A16) Cooling Fan 12 Volt Supply circuit at the Relay connector.NOTE:
The test light should be illuminated and bright. Compare the brightness to that of a direct connection to the battery.
Is the test light illuminated and bright?
Yes
- Go To Step 4
No
- Repair the (A16) Cooling Fan 12 Volt Supply circuit for an open.
- Perform the PCM VERIFICATION TEST. Refer to the appropriate Testing & Diagnostics article in Engine Performance .
- CHECK THE (N23) COOLING FAN MOTOR 1 OUTPUT VOLTAGE
- Disconnect the Cooling Fan Motor 1 harness connector.
- Using a Voltmeter connected to ground, probe the (N23) Cooling Fan Motor 1 Output circuit at the Cooling Fan Motor 1 harness connector.NOTE:
The voltage reading should be approximately Battery voltage.
Is the voltage reading equal to Battery voltage?
Yes
- Go To Step 5
No
- Repair the (N23) Cooling Fan Motor 1 Output circuit for an open or high resistance.
- Perform the PCM VERIFICATION TEST. Refer to the appropriate Testing & Diagnostics article in Engine Performance .
- CHECK THE COOLING FAN MOTOR 2 OUTPUT VOLTAGE
- Reconnect the Cooling Fan Motor 1 harness connector.
- Disconnect the Cooling Fan Motor 2 harness connector.NOTE:
Cooling Fan Motor 1 must be connected before checking for voltage at the (N24) circuit.
- Measure the voltage of the (N24) Cooling Fan Motor 2 Output circuit at the Cooling Fan Motor 2 harness connector.NOTE:
The voltage reading should be approximately Battery voltage.
Is the voltage reading equal to Battery voltage?
Yes
- Go To Step 6
No
- Go To Step 7
- CHECK THE (Z901) GROUND CIRCUIT
- Using a 12-Volt test light connected to 12 Volts, probe the (Z901) Ground circuit at the Cooling Fan Motor 2 harness connector.NOTE:
The test light should be illuminated and bright. Compare the brightness to that of a direct connection to the battery.
Is the test light illuminated and bright?
Yes
- Replace the Cooling Fan Motor 2 in accordance with the service information.
- Perform the PCM VERIFICATION TEST. Refer to the appropriate Testing & Diagnostics article in Engine Performance .
No
- Repair the (Z901) Ground circuit for an open.
- Perform the PCM VERIFICATION TEST. Refer to the appropriate Testing & Diagnostics article in Engine Performance .
- Using a 12-Volt test light connected to 12 Volts, probe the (Z901) Ground circuit at the Cooling Fan Motor 2 harness connector.
- CHECK THE COOLING FAN MOTOR 2 SUPPLY
- Turn the ignition off.
- Disconnect the Cooling Fan Motor 1 harness connector.
- Measure the resistance from the (N210) Cooling Fan Lo-Hi Control circuit at the Cooling Fan Motor 1 harness connector and the (N24) Cooling Fan Motor 2 Output circuit at the Cooling Fan Motor 2 harness connector.
Is the resistance below 5.0 Ohms?
Yes
- Replace the Cooling Fan Motor 1 in accordance with the service information.
- Perform the PCM VERIFICATION TEST. Refer to the appropriate Testing & Diagnostics article in Engine Performance .
No
- Repair the open or high resistance in the circuit or circuits. Try switching the Hi-Lo Fan Relay with a known good relay and rechecking the circuit before checking the (N210) and (N24) circuits for an open.
- Perform the PCM VERIFICATION TEST. Refer to the appropriate Testing & Diagnostics article in Engine Performance .
- CHECK THE (A16) COOLING FAN 12 VOLT SUPPLY CIRCUIT
- Turn the ignition on.
- Remove the Hi-Med. Fan Relay.
- Using a 12-Volt test light connected to ground, probe the (A16) Cooling Fan 12 Volt Supply circuit at the Relay connector.NOTE:
The test light should be illuminated and bright. Compare the brightness to that of a direct connection to the battery.
Is the test light illuminated and bright?
Yes
- Go To Step 9
No
- Repair the (A16) Cooling Fan 12 Volt Supply circuit for an open.
- Perform the PCM VERIFICATION TEST. Refer to the appropriate Testing & Diagnostics article in Engine Performance .
- CHECK THE (N23) COOLING FAN MOTOR 1 OUTPUT VOLTAGE
- Connect a jumper between the (A16) Cooling Fan 12 Volt Supply circuit and the (N23) Cooling Fan Motor 1 Output circuit at the Hi-Med. Fan Relay.
- Disconnect the Cooling Fan Motor 1 harness connector.
- Using a Voltmeter connected to ground, probe the (N23) Cooling Fan Motor 1 Output circuit at the Cooling Fan Motor 1 harness connector.NOTE:
The voltage reading should be approximately Battery voltage.
Is the voltage reading equal to Battery voltage?
Yes
- Go To Step 10
No
- Repair the (N23) Cooling Fan Motor 1 Output circuit for an open or high resistance.
- Perform the PCM VERIFICATION TEST. Refer to the appropriate Testing & Diagnostics article in Engine Performance .
- CHECK THE GROUND CIRCUIT
- With a scan tool, actuate the cooling fans in high speed operation.
- Using a 12-Volt test light connected to 12 Volts, probe the (N210) Cooling Fan Lo-Hi Control circuit at the Cooling Fan Motor 1 harness connector.NOTE:
The test light should be illuminated and bright. Compare the brightness to that of a direct connection to the battery.
Is the test light illuminated and bright?
Yes
- Replace the Cooling Fan Motor 1 in accordance with the service information.
- Perform the PCM VERIFICATION TEST. Refer to the appropriate Testing & Diagnostics article in Engine Performance .
No
- Repair the open or high resistance in the circuit or circuits. Try switching the Hi-Lo Fan Relay with a known good relay and rechecking the circuit before checking the (N210) and (Z901) circuits for an open.
- Perform the PCM VERIFICATION TEST. Refer to the appropriate Testing & Diagnostics article in Engine Performance .
- CHECK THE (A16) COOLING FAN 12 VOLT SUPPLY CIRCUIT
- Turn the ignition on.
- Remove the Series-Parallel Fan Relay.
- Using a 12-Volt test light connected to ground, probe the (A16) Cooling Fan 12 Volt Supply circuit at the Relay connector.NOTE:
The test light should be illuminated and bright. Compare the brightness to that of a direct connection to the battery.
Is the test light illuminated and bright?
Yes
- Go To Step 12
No
- Repair the (A16) Cooling Fan 12 Volt Supply circuit for an open.
- Perform the PCM VERIFICATION TEST. Refer to the appropriate Testing & Diagnostics article in Engine Performance .
- CHECK THE (N24) COOLING FAN MOTOR 2 OUTPUT VOLTAGE
- Connect a jumper between the (A16) Cooling Fan 12 Volt Supply circuit and the (N24) Cooling Fan Motor 2 Output circuit at the Series-Parallel Fan Relay.
- Disconnect the Cooling Fan Motor 2 harness connector.
- Using a Voltmeter connected to ground, probe the (N24) Cooling Fan Motor 2 Output circuit at the Cooling Fan Motor 2 harness connector.NOTE:
The voltage reading should be approximately Battery voltage.
Is the voltage reading equal to Battery voltage?
Yes
- Go To Step 13
No
- Repair the (N24) Cooling Fan Motor 2 Output circuit for an open or high resistance.
- Perform the PCM VERIFICATION TEST. Refer to the appropriate Testing & Diagnostics article in Engine Performance .
- CHECK THE (Z901) GROUND CIRCUIT
- Using a 12-Volt test light connected to 12 Volts, probe the (Z901) Ground circuit at the Cooling Fan Motor 2 harness connector.NOTE:
The test light should be illuminated and bright. Compare the brightness to that of a direct connection to the battery.
Is the test light illuminated and bright?
Yes
- Replace the Cooling Fan Motor 2 in accordance with the service information.
- Perform the PCM VERIFICATION TEST. Refer to the appropriate Testing & Diagnostics article in Engine Performance .
No
- Repair the (Z901) Ground circuit for an open or high resistance.
- Perform the PCM VERIFICATION TEST. Refer to the appropriate Testing & Diagnostics article in Engine Performance .
- Using a 12-Volt test light connected to 12 Volts, probe the (Z901) Ground circuit at the Cooling Fan Motor 2 harness connector.
Diagnose and repair any Cooling Fan Relay control circuit DTCs before proceeding with this test.