P0838

P0838-FOUR WHEEL DRIVE (4WD) SWITCH CIRCUIT LOW





For a complete wiring diagram, refer to the Wiring Information.

- When Monitored:
With the ignition on and no system undervoltage or overvoltage or supply voltage low conditions present.

- Set Condition:
The Transfer Case Selector Switch Voltage is below a specified value for a calibrated amount of time.





1. P0838 DTC IS ACTIVE

NOTE: If any other DTCs are present they must be repaired before continuing.

1. Turn the ignition off to the lock position.
2. With the scan tool, read DTCs in the CCN.

Is the status Active for this DTC?

Yes

- Go To 2

No

- Go To 7

2. TRANSFER CASE POSITION SENSOR SWITCH VOLTAGE LESS THAN 0.2 VOLTS

NOTE: Repair any system undervoltage or overvoltage DTCs that are set in this module before proceeding.

1. Ignition on, engine not running.
2. While back probing, measure the voltage between the (K77) Transfer Case Position Sensor Input circuit in the CCN C3 harness connector and Ground.

Is the voltage less than 0.2 of a volt?

Yes

- Go To 3

No

- Go To 7

3. TRANSFER CASE SELECTOR SWITCH




1. Turn the ignition off to the lock position
2. Disconnect the Transfer Case Selector Switch harness connector.
3. Connect a jumper wire between the (K77) Transfer Case Position Sensor Input circuit and the (Z940) Ground circuit in the Transfer Case Selector Switch harness connector.
4. Ignition on, engine not running.
5. While back probing, measure the voltage between the (K77) Transfer Case Position Sensor Input circuit in the CCN C3 harness connector and Ground.
6. The switch voltage should be approximately 5.0 volts.

Does the voltage display as described?

Yes

- Replace the Transfer Case Selector Switch.
- Perform the BODY VERIFICATION TEST. Body Verification Test.

No

- Go To 4

4. (K77) TRANSFER CASE POSITION SENSOR INPUT CIRCUIT SHORTED TO GROUND




1. Turn the ignition off to the lock position
2. Disconnect the CCN C3 harness connector.
3. Measure the resistance between ground and the (K77) Transfer Case Position Sensor Input circuit.

Is the resistance less than 5.0 Ohms?

Yes

- Repair the (K77) Transfer Case Position Sensor Input circuit for a short to ground.
- Perform the BODY VERIFICATION TEST. Body Verification Test.

No

- Go To 5

5. (K77) TRANSFER CASE POSITION SENSOR INPUT CIRCUIT OPEN




1. Measure the resistance of the (K77) Transfer Case Position Sensor Input circuit between the Transfer Case Selector Switch harness connector and the CCN C3 harness connector.

Is the resistance greater than 5.0 Ohms?

Yes

- Repair the (K77) Transfer Case Position Sensor Input circuit for an open.
- Perform the BODY VERIFICATION TEST. Body Verification Test.

No

- Go To 6

6. (Z940) GROUND CIRCUIT OPEN




1. Measure the resistance of the (Z940) Ground circuit between the Transfer Case Selector Switch harness connector and the CCN C3 harness connector.

Is the resistance above 5.0 Ohms?

Yes

- Repair the (Z940) Ground circuit for an open.
- Perform the BODY VERIFICATION TEST. Body Verification Test.

No

- Replace the CCN.
- Perform the BODY VERIFICATION TEST. Body Verification Test.

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.
5. While monitoring the scan tool data relative to this circuit, move the selector switch to each position several times.
6. Look for the data to change other than as expected or for the DTC to reset.

Were any problems found?

Yes

- Repair as necessary.
- Perform the AWD Control Module VERIFICATION TEST. .

No

- Test complete.