No Response From FDCM (Final Drive Control Module)

NO RESPONSE FROM FDCM (FINAL DRIVE CONTROL MODULE)

No Response From FDCM (Final Drive Control Module):

POSSIBLE CAUSES
- (A926) (A909) (A927) fused B(+) circuit open or shorted
- (Z901) (Z902) (Z913) ground circuit open
- (F921) fused run relay 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 FCM 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. FUSED B(+) CIRCUIT OPEN OR SHORTED

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

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

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




3. GROUND CIRCUIT OPEN

Using a 12-volt test light connected to 12-volts, check each Ground circuit.

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

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




4. (F921) FUSED RUN RELAY OUTPUT CIRCUIT OPEN OR SHORTED

Turn the ignition on.
Using a 12-volt test light connected to ground, check the (F921) Fused Run Relay Output circuit.

Q: Does the test light illuminate brightly?

YES: Go To 5
NO: Repair the (F921) Fused Run Relay 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 FCM C1 harness connector.
Measure the resistance of the (D65) CAN C Bus (+) circuit between the FCM 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 FCM 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