Inspection procedure 4

INSPECTION PROCEDURE 4: Radiator Fan and Condenser Fan do not Change Speed or Stop [3.8L Engine]

NOTE:
If the engine coolant temperature reaches 110°C (230°F) or higher, the radiator fan control runs the radiator fan for up to 5 minutes even after the ignition switch is turned to the "LOCK" (OFF) position [the fan stops its rotation when the engine coolant temperature decreases to 110°C (230°F) or lower.]

RADIATOR FAN AND CONDENSER FAN DRIVE CIRCUIT

Refer to Inspection procedure 3.

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 fan controller has variable control of the radiator fan motor and the condenser fan motor speeds using signals transmitted from the ECM [M/T] or PCM [A/T].

TROUBLESHOOTING HINTS

- Malfunction of fan control relay
- Malfunction of fan control module
- Malfunction of ECM [M/T] or PCM [A/T]

DIAGNOSIS

Required Special Tools:

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

STEP 1. 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 2.
NO Replace the part, then go to Step 7.
STEP 2. Check the harness wire 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 and fan control module connector A-22 damaged?

YES Repair or replace the part, then go to Step 7.

NO Go to Step 3.

STEP 3. 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 run it at idle. [Engine coolant temperature: 80°C
(176°F) or less]





(4)Measure the voltage between terminal number 10 and ground.

Q. Is the voltage 0 to 0.3 volt when the radiator fan is not operating?

YES Go to Step 7.

NO Go to Step 4.

STEP 4. Check fan control module connector A-22 and ECM [M/T] or PCM [A/T] connector B-18 for loose, corroded or damaged terminals, or terminals pushed back in the connector.









Q. Are the connectors in good condition?

YES Go to Step 5.

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

STEP 5. Check the harness wire between ECM [M/T] or PCM [A/T] connector B-18 (terminal 10) and fan control module connector A-22 (terminal 2).









Q. Are the harness wires between ECM [M/T] or PCM [A/T] connector B-18 and fan control module connector A-22 damaged?

YES Repair or replace them, then go to Step 7.

NO Go to Step 6.

STEP 6. Check the fan control module at ECM [M/T] or PCM [A/T] connector B-18.





(1)Disconnect ECM [M/T] or PCM [A/T] connector B-18.
(2)Pull out the pin 10 and connect it to the body ground.





(3)Reconnect ECM [M/T] or PCM [A/T] connector B-18 with pin 10 still removed.
(4)Turn the ignition switch to the " ON" position.

Q. Do the radiator fan motor and condenser fan motor stop?

YES Replace the ECM [M/T] or PCM [A/T].
Then go to Step 7.

NO Replace the radiator fan motor. Then go to Step 7.

STEP 7. Check the symptoms.

Q. Do the radiator fan and condenser fan operate correctly?

YES The procedure is complete.
NO Return to Step 1.