Diagnostic Test

WARNING: This page is about a different car, the 2018 RAM 2500 HD. However, it is still accessible from the selected car via links, so may be relevant.

VERIFY THE DTC IS ACTIVE
CAUTION:
Before removing the FDCM harness connector, clean the connector and locking cam area of dirt and debris. Failure to do so can result in the connector being jammed or damage to the locking cams on the harness connector or module. Do not force the assist arm when releasing or installing the harness connector.
1. Ignition on, engine not running.
2. With the scan tool, read DTCs.
  Is the DTC active at this time?
  
  Yes
  - Go To 2
  No
  - Go To 5
REAR DIFFERENTIAL POSITION SENSOR OPERATION
NOTE:
Before continuing with the below diagnostic test, ensure the FDCM harness connector seal is installed correctly. Inspect the terminals on both harness connector and the module for damage. Failure to do so can result in misdiagnoses of the system.
1. Using the scan tool, ignition on, monitor the Rear Locker Sensor state.
2. Disconnect the Rear Locker Solenoid harness connector.
  Does the state change on the scan tool from Locked to Unlocked?
  
  Yes
  - Replace the Rear Locker Solenoid.
  - Perform FDCM VERIFICATION TEST. Refer to STANDARD PROCEDURE .
  No
  - Go To 3
(T527) REAR LOCKER SENSOR SENSE CIRCUIT SHORTED TO GROUND
1. Turn the ignition off.
2. Disconnect the FDCM harness connector.
3. Measure the resistance of the (T527) Rear Locker Sensor Sense circuit in the FDCM harness connector.
  Is the resistance below 5.0 ohms?
  
  Yes
  - Repair the short to ground in the (T527) Rear Locker Sensor Sense circuit.
  - Perform FDCM VERIFICATION TEST. Refer to STANDARD PROCEDURE .
  No
  - Go To 4
FINAL DRIVE CONTROL MODULE (FDCM)
NOTE:
Before continuing, check the FDCM harness connector terminals for corrosion, damage, or terminal push out. Repair as necessary.
1. Using the schematics as a guide, inspect the wire harness and connectors. Pay particular attention to all Power and Ground circuits.
  Were there any problems found?
  
  Yes
  - Repair as necessary.
  - Perform FDCM VERIFICATION TEST. Refer to STANDARD PROCEDURE .
  No
  - Replace the Final Drive Control Module (FDCM) in accordance with the Service Information. Refer to REMOVAL . .
  - Perform FDCM VERIFICATION TEST. Refer to STANDARD PROCEDURE .
INTERMITTENT WIRING AND CONNECTORS
1. The conditions necessary to set this DTC are not present at this time.
2. Using the schematics as a guide, inspect the wiring and connectors specific to this circuit.
3. Wiggle test the wiring harness and connectors while checking for shorted and open circuits.
4. Using the scan tool, monitor the data related to this circuit while performing the wiggle test. Look for the data to change or for the DTC to reset.
  Were there any problems found?
  
  Yes
  - Repair as necessary.
  - Perform FDCM VERIFICATION TEST. Refer to STANDARD PROCEDURE .
  No
  - Test Complete.