Final Drive Control Module (FDCM)

C2100-BATTERY VOLTAGE LOW





For a complete wiring diagram, refer to the Wiring Information Electrical Diagrams.

- When Monitored:
Continuously.

- Set Condition:
The Final Drive Control Module detects that system voltage is below 8.5 volts for 10 seconds with engine RPM greater than 1500.





1. CHARGING SYSTEM DTCS PRESENT
1. Ignition on, engine not running.
2. With the scan tool, read DTCs in the Powertrain Control Module (PCM) or Engine Control Module (ECM).

Are there any Charging System or related voltage DTCs present?

Yes

- Perform the appropriate diagnostic procedure.
- For gas engine applications, Testing and Inspection.

No

- Go To 2

2. DTC IS ACTIVE
1. With the scan tool, read DTCs in the Final Drive Control Module.

Is the status Active for this DTC?

Yes

- Go To 3

No

- Go To 5

3. FINAL DRIVE CONTROL MODULE POWER CIRCUITS OPEN OR HIGH RESISTANCE




1. Turn the ignition off to the lock position
2. Disconnect the Final Drive Control Module C1 harness connector.
3. Ignition on, engine not running.
4. With a 12-volt test light connected to ground, check the Fused B+ circuits in the Final Drive Control Module C1 harness connector.

NOTE: The test light must illuminate brightly. Compare the brightness to that of a direct connection to the battery.

Does the test light illuminate brightly for each of the Fused B+ circuits?

Yes

- Replace the Final Drive Control Module.
- Perform the FDCM VERIFICATION TEST. FDCM Verification Test.

No

- Repair the Fused B+ circuit(s) for an open circuit or high resistance.
- Perform the FDCM VERIFICATION TEST. FDCM Verification Test.

4. FINAL DRIVE CONTROL MODULE

View repair.

Repair

- Replace the Final Drive Control Module.
- Perform the FDCM VERIFICATION TEST.FDCM Verification Test.

5. INTERMITTENT WIRING AND CONNECTORS
1. The conditions necessary to set this DTC are not present at this time.
2. Using the wiring diagram/schematic as a guide, inspect the wiring and connectors.
3. While monitoring the scan tool data relative to this circuit, wiggle test the wiring and connectors.
4. 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. FDCM Verification Test.

No

- Test complete.