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 60 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.

Are there any Charging System or related voltage DTCs present?

Yes

- Perform the appropriate Charging System DTC diagnostic procedures before continuing with this test 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. (Z910) GROUND CIRCUIT OPEN OR HIGH RESISTANCE




1. Turn the ignition off to the lock position
2. Disconnect the FDCM C1 harness connector.
3. Disconnect the FDCM C2 harness connector.
4. Ignition on, engine not running.With a 12-volt test light connected to B+, check the (Z910) Ground circuit in the FDCM C2 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 Ground circuits?

Yes

- Go To 4

No

- Repair the (Z910) Ground circuit for an open circuit or high resistance.
- Perform the TRANSFER CASE VERIFICATION TEST Transfer Case Verification Test.

4. POWER CIRCUITS OPEN OR HIGH RESISTANCE




1. With a 12-volt test light connected to ground, check the (F943) Fused Ignition Switch Output circuit in the FDCM C1 harness connector and the (A115) Fused B+ circuit in the FDCM C2 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 circuits?

Yes

- Replace the Final Drive Control Module (FDCM).
- Perform the TRANSFER CASE VERIFICATION TEST Transfer Case Verification Test.

No

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

No

- Test complete.