No Response From FDCM (Final Drive Control Module)

For a complete wiring diagram, refer to appropriate SYSTEM WIRING DIAGRAMS article  .

Fig 1: Final Drive Control Module Circuit Diagram

Courtesy of CHRYSLER GROUP, LLC

1. TEST FOR INTERMITTENT CONDITION 
   NOTE: Check for any TSB(s) related to the condition. If a TSB applies, perform the procedure outlined in the TSB before continuing. 
   1. Turn the ignition on.
      NOTE: Make sure the battery voltage is between 10.0 and 16.0 volts. 
   2. With the scan tool, read the module status.
      NOTE: Check the BCM for any active CAN DTCs and perform the appropriate diagnostics before proceeding. Refer to  BODY CONTROL MODULE (BCM) - DIAGNOSTIC CODE INDEX - 2500 HD & 3500 HD  . 

      Does the scan tool indicate that the module is active on the bus? 

      Yes 

      • The no response condition is not present at this time. Using the wiring diagrams as a guide, check all related splices and connectors for signs of water intrusion, corrosion, pushed out or bent terminals, and correct pin tension.

      No 

      • Go To  2
2. CHECK THE (A959) FUSED B(+) CIRCUIT FOR AN OPEN OR SHORT 
   1. Turn the ignition off.
   2. Disconnect the FDCM harness connector.
   3. Turn the ignition on.
   4. Using a 12-volt test light connected to ground, check the (A959) Fused B(+) circuit.

      Does the test light illuminate brightly? 

      Yes 

      • Go to  3

      No 

      • Repair the (A959) Fused B(+) circuit for an open or short.
      • Perform the BCM VERIFICATION TEST. Refer to BODY VERIFICATION TEST .
3. CHECK THE (F946) FUSED IGNITION SWITCH OUTPUT (RUN-START) CIRCUIT FOR AN OPEN OR SHORT 
   1. Using a 12-volt test light connected to ground, check the (F946) Fused Ignition Switch Output (Run-Start) circuit.

      Does the test light illuminate brightly? 

      Yes 

      • Go to  4

      No 

      • Repair the (F946) Fused Ignition Switch Output (Run-Start) circuit for an open or short.
      • Perform the BCM VERIFICATION TEST. Refer to BODY VERIFICATION TEST .
4. CHECK THE (Z904) GROUND CIRCUIT FOR AN OPEN 
   1. Turn the ignition off.
   2. Using a 12-volt test light connected to 12-volts, check the (Z904) Ground circuit.

      Does the test light illuminate brightly? 

      Yes 

      • Go to  5

      No 

      • Repair the (Z904) Ground circuit for an open.
      • Perform the BCM VERIFICATION TEST. Refer to BODY VERIFICATION TEST .
5. CHECK THE (D303) CAN C(+) BUS CIRCUIT FOR AN OPEN 
   1. Disconnect the Star Can C Dash C2 harness connector.
   2. Measure the resistance of the (D303) CAN C Bus (+) circuit between the Star Can C Dash C2 harness connector and the FDCM harness connector.

      Is the resistances below 5.0 Ohms? 

      Yes 

      • Go to  6

      No 

      • Repair the (D303) CAN C(+) Bus circuit for an open.
      • Perform the BCM VERIFICATION TEST. Refer to BODY VERIFICATION TEST .
6. CHECK THE (D304) CAN C(-) BUS CIRCUIT FOR AN OPEN 
   1. Measure the resistance of the (D304) CAN C Bus (-) circuit between the Star Can C Dash C2 harness connector and the FDCM harness connector.

      Are the resistances below 5.0 Ohms? 

      Yes 

      • Replace the Final Drive Control Module (FDCM) in accordance with the Service Information. (Refer to 02 - Front Suspension/Front, Link and Coil/ACTUATOR, Stabilizer Bar/Removal).
      • Perform the BCM VERIFICATION TEST. Refer to BODY VERIFICATION TEST .

      No 

      • Repair the (D304) CAN C(-) Bus circuit for an open.
      • Perform the BCM VERIFICATION TEST. Refer to BODY VERIFICATION TEST .