Inspection Procedure 3

INSPECTION PROCEDURE 3: Radiator Fan and Condenser Fan do not Operate [3.8L Engine]

Radiator Fan and Condenser Fan Drive Circuit Connectors: A-12X, B16X, A-15:

Connectors: A22, A22-1, A-01:

CIRCUIT OPERATION
^ The fan control module is powered from fusible link number 23.
^ The ECM [M/T] or PCM [A/T] judges the required revolution speed of radiator fan motor and condenser fan motor using the input signals transmitted from A/C switch, automatic compressor controller, vehicle speed sensor and engine coolant temperature sensor. The ECM [M/T] or PCM [A/T] activates the fan control module to drive the radiator fan motor and condenser fan motor.

TECHNICAL DESCRIPTION
^ The cause could be a malfunction of the fan control module power supply or ground circuit.
^ The cause could also be a malfunction of the fan control module or the ECM [M/T] or PCM [A/T].

TROUBLESHOOTING HINTS
^ Malfunction of fusible link
^ Malfunction of fan control relay
^ Malfunction of MFI relay
^ Malfunction of fan control module
^ Malfunction of ECM [M/T] or PCM [A/T]
^ Damaged wiring harness or connector

DIAGNOSIS

Required Special Tools:
^ MB992006: Extra Fine Probe
^ MB991223: Harness Set
^ MB991923: Power Plant ECU Check Harness

STEP 1. Check the circuit at fan control module connector A-22 (terminal 3).

Connector: A-22:

(1) Disconnect fan control module connector A-22, and measure at the harness side connector.





(2) Measure the voltage between terminal number 3 and ground.
^ When the ignition switch is turned to the "ON" position, voltage should measure battery positive voltage.

Q: Is there voltage battery positive voltage when the ignition switch is turned to the "ON" position?
YES: Go to Step 8.
NO: Go to Step 2.

STEP 2. Check the fan control relay.
Q: Is the fan control relay in good condition?
YES: Go to Step 3.
NO: Replace it, then go to Step 1.

STEP 3. Check the MFI relay.
Q: Is the MFI relay in good condition?
YES: Go to Step 4.
NO: Replace it, then go to Step 1.

STEP 4. Check for harness damage between fusible link number 23 and fan control relay connector A-12X (terminal 4).

Connector: A-12X:

Q: Are the harness wires between fusible link number 23 and fan control relay connector A-12X damaged?
YES: Repair or replace them, then go to Step 14.
NO: Go to Step 5.

STEP 5. Check for harness damage between fan control relay connector A-12X (terminal 2) and fan control module connector A-22 (terminal 3).

Connector: A-12X:

Connector: A-22:

Q: Are the harness wires between fan control relay connector A-12X (terminal 2) and fan control module connector A-22 (terminal 3) damaged?
YES: Repair or replace them, then go to Step 14.
NO: Go to Step 6.

STEP 6. Check intermediate connector A-15 for loose, corroded or damaged terminals, or terminals pushed back in the connector.

Connector: A-15:

Q: Are the connectors and terminals in good condition?
YES: Go to Step 7.
NO: Repair or replace the damaged components. Refer to Harness Connector Inspection.

STEP 7. Check for harness damage between MFI relay connector B-16X and fan control relay connector A-12X.

Connector: A-12X, B-16X:

Q: Are the harness wires between MFI relay connector B-16X (terminal 4) and fan control relay connector A-12X (terminal 1) damaged?
YES: Repair or replace them, then go to Step 14.
NO: Go to Step 8.

STEP 8. Check for harness damage between fan control relay connector A-12X (terminal 3) and ground.

Connector: A-12X:

Q: Are the harness wires between fan control relay connector A-12X (terminal 3) and ground damaged?
YES: Repair or replace them, then go to Step 14.
NO: Go to Step 9.

STEP 9. Check the circuit at fan control module connector A-22 (terminal 1).

Connector: A-22:

(1) Disconnect fan control module connector A-22, and measure at the harness side connector.





(2) Measure the resistance between terminal number 1 and ground.
Q: Is the resistance less than 2 ohms?
YES: Go to Step 11.
NO: Go to Step 10.

STEP 10. Check the harness wire between fan control module connector A-22 (terminal 1) and ground.

Connector: A-22:

Q: Are the harness wires between fan control module connector A-22 (terminal 1) and ground damaged?
YES: Repair or replace them, then go to Step 14.
NO: Go to Step 11.

STEP 11. Measure the output circuit voltage at ECM [M/T] or PCM [A/T] connector B-18 (terminal 10) by using check harness special tool MB991923.

Connector: B-18:

(1) Disconnect all the connectors from the ECM [M/T] or PCM [A/T].





(2) Connect special tool MB991923 (check harness) between the ECM [M/T] or PCM [A/T] and the body-side harness connector.
(3) Start the engine and allow it to idle.





(4) Measure the voltage between terminal number 10 and ground.
Q: Is the voltage 0.7 volt or more when the radiator fan is operating?
YES: Go to Step 13.
NO: Go to Step 12.

STEP 12. Check the harness wire between ECM [M/T] or PCM [A/T] connector B-18 and fan control module connector A-22.

Connector: A-22:

Connector: B-18:

Q: Are the harness wires between ECM [M/T] or PCM [A/T] connector B-18 (terminal 10) and fan control module connector A-22 (terminal 2) damaged?
YES: Repair or replace them, then go to Step 14.
NO: Go to Step 13.

STEP 13. Check the fan control module at ECM [M/T] or PCM [A/T] connector B-18 (terminal 10).

Connector: B-18:

(1) Do not disconnect ECM [M/T] or PCM [A/T] connector B-18.
(2) Pull out terminal number 10.
(3) Turn the ignition switch to the "ON" position.
Q: Do the radiator fan motor and condenser fan motor operate?
YES: Replace the ECM [M/T] or PCM [A/T]. Then go to Step 14.
NO: Replace the radiator fan motor. Then go to Step 14.

STEP 14. Check the symptoms.
Q: Do the radiator fan and condenser fan operate correctly?
YES: The procedure is complete.
NO: Return to Step 1.