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Home >> Dodge and Ram >> 2025 >> Durango R/T Plus >> Repair and Diagnosis (Single Page) >> Transmission >> Transmission Control Systems >> (Electronic Shift Module (ESM) - Electrical Diagnostics - 8HP70 Automatic Transmission) >> DTC Troubleshooting >> U0101-08 Lost Communication With TCM-Bus Signal / Message Failures >> Diagnostic Test
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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 

  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 

  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. Refer to: ELECTRONIC SHIFT MODULE (ESM) VERIFICATION TEST  .
  4. CHECK THE CAN C BUS (+) CIRCUIT FOR A SHORT TO VOLTAGE 
    1. Measure the voltage between the CAN C BUS (+) circuit and ground.

      Is the voltage above 5.0 volts?

      Yes 

      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.

      Is the resistance below 10K Ohms?

      Yes 

      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 in accordance to the Service Information. Refer to SHIFTER, TRANSMISSION, REMOVAL .
      • Perform the ESM VERIFICATION TEST. Refer to: ELECTRONIC SHIFT MODULE (ESM) VERIFICATION TEST  .