Transmission Control Module (TCM)

P0562-BATTERY VOLTAGE LOW





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

Theory of Operation

The Transmission Control Module (TCM) monitors ignition voltage. The DTC will set if the monitored battery voltage drops below 8.5 Volts and a temporary limp in will be activated. If the voltage rises above 9.0 Volts, normal operations is resumed and the TCM will record the DTC as a one trip fault. The DTC will only mature to a full DTC if the voltage is less than 8.5 Volts with a engine speed greater than 2000 RPM for a least 60 seconds.

- When Monitored:
Continuously with the ignition on.

- Set Condition:
When monitored battery voltage drops below 8.5 Volts.





Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. . Testing and Inspection

1. CHECK FOR ENGINE CHARGING SYSTEM DTCS
1. Using the scan tool, read Engine DTCs.

Are there any Engine Charging System DTCs present?

Yes

- For Diesel engine, Testing and Inspection Perform the appropriate charging system diagnostic procedure.
- For Gas engine, Testing and Inspection Perform the appropriate charging system diagnostic procedure.
- Perform the NAG1 TRANSMISSION VERIFICATION TEST. NAG1 Transmission Verification Test.

No

- Go To 2

2. CHECK SYSTEM VOLTAGE
1. Start the engine.
2. Using the scan tool, under transmission, check system voltage.

Is the transmission system voltage above 9.0 volts?

Yes

- Go To 7

No

- Go To 3

3. CHECK (F942) FUSED IGNITION SWITCH OUTPUT (RUN-START) CIRCUIT




1. Turn the ignition off to the lock position.
2. Remove the Transmission Control relay.
3. Ignition on, engine not running.
4. Using a 12-volt test light connected to ground, check the (F942) Fused Ignition Switch Output (Run-Start) circuit in the Transmission Relay 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?

Yes

- Go To 4

No

- Repair the (F942) Fused Ignition Switch Output (Run-Start) circuit for high resistance.
- Perform the NAG1 TRANSMISSION VERIFICATION TEST. NAG1 Transmission Verification Test.

4. CHECK THE (F946) TRANSMISSION RELAY OUTPUT CIRCUIT




1. Turn the ignition off to the lock position.
2. Remove the Transmission Relay.
3. Connect a jumper wire between the (F942) Fused Ignition Switch Output (Run-Start) circuit and the (F946) Transmission Relay Output circuit in the Transmission Relay connector.
4. Start the engine.
5. Using the scan tool, under transmission, check system voltage.

Is the transmission system voltage above 9.0 volts?

Yes

- Replace the Transmission Relay.
- Perform the NAG1 TRANSMISSION VERIFICATION TEST. NAG1 Transmission Verification Test.

No

- Go To 5

5. CHECK THE (F946) TRANSMISSION RELAY OUTPUT CIRCUIT




1. Turn the ignition off to the lock position.
2. Disconnect the TCM C1 harness connector.
3. Ignition on, engine not running.
4. Using a 12-volt test light connected to ground, check the (F946) Transmission Relay Output circuit in the TCM 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?

Yes

- Go To 6

No

- Repair the (F946) Transmission Relay Output circuit for high resistance.
- Perform the NAG1 TRANSMISSION VERIFICATION TEST. NAG1 Transmission Verification Test.

6. CHECK (Z904) GROUND CIRCUIT




1. Turn the ignition off to the lock position.
2. Using a 12-volt test light connected to 12-volts, check the (Z904) Ground circuit in the TCM C1 harness connector.

Does the test light illuminate brightly?

Yes

- Using the schematics as a guide, check the Transmission Control Module (TCM) terminals for corrosion, damage, or terminal push out. Pay particular attention to all power and ground circuits. If no problems are found, replace the TCM. . Transmission Control Module - Removal
- Perform the NAG1 TRANSMISSION VERIFICATION TEST. NAG1 Transmission Verification Test.

No

- Repair the (Z904) Ground circuit for high resistance.
- Perform the NAG1 TRANSMISSION VERIFICATION TEST. NAG1 Transmission Verification Test.

7. CHECK THE WIRING AND CONNECTORS
1. The conditions necessary to set this DTC are not present at this time.
2. Using the schematics as a guide, inspect the wiring and connectors specific to this circuit.
3. Wiggle the wires while checking for shorted and open circuits.

Where there any problems found?

Yes

- Repair as necessary.
- Perform the NAG1 TRANSMISSION VERIFICATION TEST. NAG1 Transmission Verification Test.

No

- Test Complete.