P1DB1

P1DB1-TCM SYSTEM VOLTAGE EXCESSIVELY LOW

For a complete wiring diagram Refer to the Wiring Information.

Theory of Operation

The purpose of the diagnostic is to monitor the system voltage level at the Transmission Control Module (TCM). If the TCM supply voltage drops below a calibrated level that is lower than the system voltage, then the high side switch is not activated then DTC P1DB1 is set.

- When Monitored:
When the ignition switch is turned to the run position and the high side switch is activated with the shifter in Park or Neutral.

Engine speed via CAN or input speed signal greater than a threshold with the shifter in Drive or Reverse.

- Set Condition:
The read value does not match the written value in any RAM location.





Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. 8HP45 Pre-Diagnostic Troubleshooting Procedure

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

Are any Engine Charging System DTCs present?

Yes

- Repair Charging System DTCs before proceeding. Charging System.
- Perform the TRANSMISSION VERIFICATION TEST. Verification Tests.

No

- Go To 2

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

Is the transmission system voltage above 9.0 volts?

Yes

- Go To 3

No

- Go To 4

3. INTERMITTENT 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 any problems found?

Yes

- Repair as necessary.
- Perform the TRANSMISSION VERIFICATION TEST. Verification Tests.

No

- Go To 4

4. CHECK THE BATTERY CIRCUIT
1. Ignition ON, Engine Not Running.
2. Using a 12-volt test light connected to ground, check the battery circuit at the Transmission Control Module Assembly (TCMA) 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

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

No

- Repair the battery circuit for an open or high resistance.
- Perform the TRANSMISSION VERIFICATION TEST. Verification Tests.