Inspection procedure 3

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






















CIRCUIT OPERATION

- The fan control module is powered from fusible link number 2.
- 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:

- MB991223: Harness Set
- MB992006: Extra Fine Probe
- MB991923: Power Plant ECU Check Harness

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





(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.

Refer to Fan Control Relay Continuity Check.

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.

Refer to Testing and Inspection.

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 2 and fan control relay connector A-12X (terminal 4).





Q. Are the harness wires between fusible link number 2 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).









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.





Q. Are the connectors and terminals in good condition?

YES Go to Step 7.

NO Repair or replace the damaged components. Harness Connector Inspection.

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





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.





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).





(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.





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.





(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.









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).





(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.