Electronic Shift Module (ESM) - 8HP45

U0402-00-IMPLAUSIBLE DATA RECEIVED FROM TCM

For a complete wiring diagram Refer to the Wiring Information.

Theory of Operation

The Electronic Shift Module (ESM) performs various internal tests to verify proper controller operation. This DTC indicates there is a communication issue between the ESM and Transmission Control Module (TCM).

- When Monitored:
Continuously with the ignition in the run position.

- Set Condition:
If the ESM detects an invalid CAN BUS signal from the TCM.





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

Diagnostic Test

1. VERIFY THE DTC IS ACTIVE

NOTE: Make sure the battery voltage is between 10 and 16 volts before proceeding.

1. With the scan tool, read active DTCs.

Is this DTC active?

Yes

- Go To 2

No

- Manufacturer Code Charts and perform the STORED LOST COMMUNICATION DTCs diagnostic procedure.

2. VERIFY THE ESM IS ACTIVE ON THE BUS
1. Turn the ignition ON.
2. With the scan tool, select Network Diagnostics.
3. Verify the ESM is active on the BUS.

Is the ESM active on the BUS?

Yes

- Go To 3

No

- Manufacturer Code Charts and perform the NO RESPONSE FROM ESM (ELECTRONIC SHIFT MODULE) diagnostic procedure.

3. CYCLE IGNITION
1. Cycle the ignition from RUN to OFF three times ending with the key in the RUN position.

Does the DTC become active?

Yes

- Go To 4

No

- The 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.
- Perform the ESM VERIFICATION TEST. 8HP45 Transmission Verification Test.

4. CHECK THE CAN C BUS (+) CIRCUIT FOR A SHORT TO VOLTAGE
1. Measure the voltage between the CAN C BUS (+) circuit at the ESM connector and ground.

Is the voltage above 5.0 volts?

Yes

- Repair the short to voltage in the CAN C BUS (+) circuit.
- Perform the ESM VERIFICATION TEST. 8HP45 Transmission Verification Test.

No

- Go To 5

5. CHECK THE CAN C BUS (-) CIRCUIT FOR A SHORT TO GROUND
1. Turn the ignition OFF.
2. Measure the resistance between ground and the CAN C BUS (-) circuit at the ESM connector and ground.

Is the resistance below 10K Ohms?

Yes

- Repair the short to ground in the CAN C BUS (-) circuit.
- Perform the ESM VERIFICATION TEST. 8HP45 Transmission Verification Test.

No

- Using the schematics as a guide, check the ESM terminals for corrosion, damage or terminal push out. Pay particular attention to all power and ground circuits. If no problems are found, replace the Shift Lever Assembly. Transmission Shifter - Removal.
- Perform the ESM VERIFICATION TEST. 8HP45 Transmission Verification Test.