[Clarky]

This is the test procedure for C1438 (copy & paste), very time consuming.

C1438-TRANSFER CASE DIFFERENTIAL CLUTCH WORN

(For a complete wiring diagram, refer to the Wiring Information)


When Monitored:

The ignition on, engine running. No Under/Overvoltage, and/or encoder error DTCs present. When shifted into 4-Low or in 4-high.

Set Condition:

The Final Drive Control Module (FDCM) is unable to fully lock the T-Case (in Either High or Low) because the T-Case clutch is worn.


Possible Causes

(K504) DRIVETRAIN 5 VOLT SUPPLY CIRCUIT OPEN OR HIGH RESISTANCE
(T313) MODE SENSOR SIGNAL CIRCUIT OPEN OR HIGH RESISTANCE
(K594) DRIVETRAIN SENSOR RETURN CIRCUIT OPEN OR HIGH RESISTANCE
TRANSFER CASE CLUTCH
FINAL DRIVE CONTROL MODULE (FDCM)


1.DTC IS ACTIVE

NOTE: Diagnose and repair any system voltage or Transfer Case related DTCs in the FDCM before continuing with this test.

1. Ignition on, engine running.

2. With the scan tool, clear stored DTCs.

3. Test drive the vehicle.

4. During the test drive, move the Transfer Case Selector Switch to each position several times in accordance with the Service Information.

5. With the scan tool, read DTCs.

Does this DTC reset?

Yes

Go To 2

No


Go To 7

2.TRANSFER CASE POSITION SENSOR VOLTAGE

1. Turn the ignition off to the lock position.

2. Disconnect the Transfer Case Motor harness connector.

3. Connect a jumper wire between the (T313) Mode Sensor Signal circuit and the (K594) Drivetrain Sensor Return circuit.

4. Ignition on, engine running.

5. With the scan tool, read the T-Case Position Sensor voltage.

6. The displayed voltage should be approximately 0.0 volts with the jumper wire in place.

Does the voltage display as described?

Yes

Replace the Transfer Case Clutch in accordance with the Service Information.

Perform the TRANSFER CASE VERIFICATION (Refer to 28 - DTC-Based Diagnostics/MODULE, Final Drive Control (FDCM) - Standard Procedure)

No

Go To 3

3.TRANSFER CASE POSITION SENSOR VOLTAGE

1. Turn the ignition off to the lock position.

2. Connect a jumper wire between the (T313) Mode Sensor Signal circuit and the (K504) Drivetrain 5 Volt Supply circuit in the Transfer Case Motor harness connector.

3. Ignition on, engine running.

4. With the scan tool, monitor the T-Case Position Sensor voltage in the FDCM.

Is the voltage between 4.8 volts and 5.2 volts?

Yes

Replace or Repair the Transfer Case Clutch in accordance with the Service Information.

Perform the TRANSFER CASE VERIFICATION (Refer to 28 - DTC-Based Diagnostics/MODULE, Final Drive Control (FDCM) - Standard Procedure)

No

Go To 4

4.(K504) DRIVETRAIN 5 VOLT SUPPLY CIRCUIT HIGH RESISTANCE

1. Turn the ignition off to the lock position

2. Disconnect the Final Drive Control Module C2 harness connector.

3. Measure the resistance of the (K504) Drivetrain 5 Volt Supply circuit between the Transfer Case Motor harness connector and the Final Drive Control Module C2 harness connector.

Is the resistance above 5.0 ohms?

Yes

Repair the high resistance in the (K504) Drivetrain 5 Volt Supply circuit.

Perform the TRANSFER CASE VERIFICATION (Refer to 28 - DTC-Based Diagnostics/MODULE, Final Drive Control (FDCM) - Standard Procedure).

No

Go To 5

5.(T313) MODE SENSOR SIGNAL CIRCUIT HIGH RESISTANCE

1. Turn the ignition off to the lock position

2. Disconnect the Final Drive Control Module C2 harness connector.

3. Measure the resistance of the (T313) Mode Sensor Signal circuit between the Transfer Case Motor harness connector and the Final Drive Control Module C2 harness connector.

Is the resistance above 5.0 ohms?

Yes

Repair the high resistance in the (T313) Mode Sensor Signal circuit.

Perform the TRANSFER CASE VERIFICATION (Refer to 28 - DTC-Based Diagnostics/MODULE, Final Drive Control (FDCM) - Standard Procedure).

No

Go To 6

6.(K594) DRIVETRAIN SENSOR RETURN CIRCUIT HIGH RESISTANCE

1. Measure the resistance of the (K594) Drivetrain Sensor Return circuit between the Transfer Case Motor harness connector and the Final Drive Control Module C2 harness connector.

Is the resistance below 5.0 ohms?

Yes

Replace the Final Drive Control Module (FDCM) in accordance with the Service Information.

Perform the TRANSFER CASE VERIFICATION (Refer to 28 - DTC-Based Diagnostics/MODULE, Final Drive Control (FDCM) - Standard Procedure).

No

Repair the high resistance in the (K594) Drivetrain Sensor Return circuit.

Perform the TRANSFER CASE VERIFICATION (Refer to 28 - DTC-Based Diagnostics/MODULE, Final Drive Control (FDCM) - Standard Procedure).

7.INTERMITTENT WIRING AND CONNECTORS

1. The conditions necessary to set this DTC are not present at this time.

2. Using the wiring diagram/schematic as a guide, inspect the wiring and connectors.

3. While monitoring the scan tool data relative to this circuit, wiggle test the wiring and connectors.

4. Look for the data to change or for the DTC to reset during the wiggle test.

Were any problems found?

Yes

Repair as necessary.

Perform the TRANSFER CASE VERIFICATION (Refer to 28 - DTC-Based Diagnostics/MODULE, Final Drive Control (FDCM) - Standard Procedure).

No

Test complete.