C2123

C2123-T-CASE/DIFFERENTIAL SWITCH SUPPLY VOLTAGE CIRCUIT HIGH





For a complete wiring diagram refer to diagrams.
^ When Monitored:
With the ignition on and no system undervoltage or overvoltage condition present.
^ Set Condition:
The Final Drive Control Module detects that the Locker Switch Supply voltage and the Transfer Case Position Sense voltage are greater than 5.0 volts for 10 seconds.

Possible Causes

- INTERMITTENT T-CASE/DIFFERENTIAL SWITCH SUPPLY VOLTAGE CIRCUIT HIGH
- (K77) TRANSFER CASE POSITION SENSE CIRCUIT SHORT TO VOLTAGE
- (K537) LOCKER SWITCH SUPPLY CIRCUIT SHORT TO VOLTAGE
- FINAL DRIVE CONTROL MODULE

Diagnostic Test
1. (K77) TRANSFER CASE POSITION SENSE VOLTAGE GREATER THAN 5.0 VOLTS





Turn the ignition on. Measure the voltage of the (K77) Transfer Case Position Sense circuit by backprobing the Transfer Case Position Sensor harness connector.

Is the voltage greater than 5.0 volts?
Yes >>Go to 2
No >>Go to 5

2. (K77) TRANSFER CASE POSITION SENSE CIRCUIT SHORT TO VOLTAGE





Turn the ignition off.
Disconnect the Transfer Case Position Sensor harness connector.
Disconnect the Final Drive Control Module harness connector.
Measure the voltage of the (K77) Transfer Case Position Sense circuit at the Transfer Case Position Sensor harness connector.

Is there any voltage present?
Yes >>Repair the (K77) Transfer Case Position Sense circuit for a short to voltage.
Perform the FDCM VERIFICATION TEST.
No >>Go to 3

3. (K537) LOCKER SWITCH SUPPLY CIRCUIT SHORT TO VOLTAGE





Turn the ignition off.
Disconnect the Axle Lock Switch harness connector.
Turn the ignition on.
Measure the voltage of the (T537) Locker Switch Supply circuit at the Axle Lock Switch harness connector.

Is there any voltage present?
Yes >>Repair the (K537) Locker Switch Supply circuit for a short to voltage.
Perform the FDCM VERIFICATION TEST.
No >>Go to 4

4. FINAL DRIVE CONTROL MODULE
View repair.

Repair
Replace the Final Drive Control Module in accordance with the Service information.
Perform the FDCM VERIFICATION TEST.
5. INTERMITTENT WIRING AND CONNECTORS
The conditions necessary to set this DTC are not present at this time.
Using the wiring diagram/schematic as a guide, inspect the wiring and connectors.
While monitoring the scan tool data relative to this circuit, wiggle test the wiring and connectors.
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 FDCM VERIFICATION TEST.
No >>Test complete.