No Response From FDCM (Final Drive Control Module) (Power Wagon Only)

NO RESPONSE FROM FDCM (FINAL DRIVE CONTROL MODULE) (POWER WAGON ONLY)

No Response From FDCM (Final Drive Control Module) (Power Wagon Only):

POSSIBLE CAUSES
- (A121) fused B(+) circuit open or shorted
- (Z935) ground circuit open
- (F21) fused ignition switch output circuit open or shorted
- (D65) CAN C BUS (+) circuit open
- (D64) CAN C BUS (-) circuit open
- Final drive control module

DIAGNOSTIC TEST

1. TEST FOR INTERMITTENT CONDITION
Turn the ignition on.

NOTE: Ensure the IOD fuse is installed and battery voltage is between 10.0 and 16.0 volts.

With the scan tool, select ECU view.

NOTE:
- A red X will be next to the module that is not communicating, indicating that the module is not active on the Bus network. A green check indicates that the module is active on the Bus network.
- Check the TIPM for any active CAN C hardware DTCs, perform DTC before proceeding.

Q: Does the scan tool display a red X next to the module?

YES: Go To 2
NO: The no response condition is not present at this time. Using the wiring diagram/schematic as a guide,inspect the wiring for chafed, pierced, pinched, and partially broken wires and the wiring harness connectors for broken, bent, pushed out, and corroded terminals.

2. (A121) FUSED B(+) CIRCUIT OPEN OR SHORTED




Turn the ignition off.
Disconnect the Final Drive Control Module harness connector.
Using a 12-volt test light connected to ground, check the (A121) Fused B(+) circuit.

Q: Does the test light illuminate brightly?

YES: Go To 3
NO: Repair the (A121) Fused B(+) circuit for an open or short.
Perform the FDCM VERIFICATION TEST. FDCM Verification Test

3. (Z935) GROUND CIRCUIT OPEN




Using a 12-volt test light connected to 12-volts, check the (Z935) Ground circuit.

Q: Does the test light illuminate brightly for each circuit?

YES: Go To 4
NO: Repair the (Z935) ground circuit for an open.
Perform the FDCM VERIFICATION TEST. FDCM Verification Test

4. (F21) FUSED IGNITION SWITCH OUTPUT CIRCUIT OPEN OR SHORTED




Turn the ignition on.
Using a 12-volt test light connected to ground, check the (F21) Fused Ignition Switch Output circuit.

Q: Does the test light illuminate brightly?

YES: Go To 5
NO: Repair the (F21) Fused Ignition Switch Output circuit for an open or short.
Perform the FDCM VERIFICATION TEST. FDCM Verification Test

5. (D65) CAN C BUS (+) CIRCUIT OPEN




Turn the ignition off.
Disconnect the TIPM C6 harness connector.
Measure the resistance of the (D65) CAN C Bus (+) circuit between the TIPM connector and the FDCM connector.

Q: Is resistance below 5.0 ohms?

YES: Go To 6
NO: Repair the (D65) CAN C Bus (+) circuit for an open.
Perform the FDCM VERIFICATION TEST. FDCM Verification Test

6. (D64) CAN C BUS (-) CIRCUIT OPEN




Measure the resistance of the (D64) CAN C Bus (-) circuit between the TIPM connector and the FDCM connector.

Q: Is resistance below 5.0 ohms?

YES: Replace the Final Drive Control Module.
Perform the FDCM VERIFICATION TEST. FDCM Verification Test
NO: Repair the (D64) CAN C Bus (-) circuit for an open.
Perform the FDCM VERIFICATION TEST. FDCM Verification Test