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

For a complete wiring diagram Refer to Section 8W

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.

Possible Causes

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

(K77) TRANSFER CASE POSITION SENSOR INPUT CIRCUIT OPEN

(Z940) GROUND CIRCUIT OPEN

TRANSFER CASE SELECTOR SWITCH

INSTRUMENT CLUSTER (CCN)

1.P0838 DTC IS ACTIVE

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

Is the status Active for this DTC?

Yes

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.

Is the voltage less than 0.2 volts?

Yes

3.TRANSFER CASE SELECTOR SWITCH

Does the voltage display as described?

Yes

Replace the Transfer Case Selector Switch.
Perform BODY VERIFICATION TEST - VER 1. (Refer to 8 - ELECTRICAL/ELECTRONIC CONTROL MODULES - STANDARD PROCEDURE)

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

Is the resistance less than 5.0 ohms?

Yes

Repair the (K77) Transfer Case Position Sensor Input circuit for a short to ground.
Perform BODY VERIFICATION TEST - VER 1. (Refer to 8 - ELECTRICAL/ELECTRONIC CONTROL MODULES - STANDARD PROCEDURE)

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

Is the resistance greater than 5.0 ohms?

Yes

Repair the (K77) Transfer Case Position Sensor Input circuit for an open.
Perform BODY VERIFICATION TEST - VER 1. (Refer to 8 - ELECTRICAL/ELECTRONIC CONTROL MODULES - STANDARD PROCEDURE)

6.(Z940) GROUND CIRCUIT OPEN

Is the resistance above 5.0 ohms?

Yes

Repair the (Z940) Ground circuit for an open.
Perform BODY VERIFICATION TEST - VER 1. (Refer to 8 - ELECTRICAL/ELECTRONIC CONTROL MODULES - STANDARD PROCEDURE)

Replace the CCN in accordance with the Service Information.
Perform BODY VERIFICATION TEST - VER 1. (Refer to 8 - ELECTRICAL/ELECTRONIC CONTROL MODULES - STANDARD PROCEDURE)

7.INTERMITTENT WIRING AND CONNECTORS

Were any problems found?

Yes