AUTOMATIC TRANSAXLE SYSTEM, Diagnostic DTC:U0100

DTC Code DTC Name
U0100 Lost Communication with ECM / PCM "A"

DESCRIPTION

The engine control unit communicates with the TCM using the Controller Area Network (CAN).

If there is a problem in this communication, the TCM sets a DTC.

DTC No. DTC Detection Condition Trouble Area
U0100

Following conditions are met for 1.25 seconds (1 trip detection logic):


  • Engine switch on (IG)

  • Battery voltage is 10.5 V or more

  • No communication between the engine control ECU (ECM) and TCM

  • Harness and connector

  • ECM

  • TCM

MONITOR STRATEGY

Related DTCs U0100: Verify communication
Required Sensors/Components (Main) TCM
Required Sensors/Components (Related) -
Frequency of Operation Continuous
Duration 1.25 seconds
MIL Operation Immediate
Sequence of Operation None

TYPICAL ENABLING CONDITIONS

Monitor runs whenever following DTCs not present None
Battery Voltage 10.5 V or more
Engine switch on (IG)
Starter OFF

TYPICAL MALFUNCTION THRESHOLDS

Communication between TCM and ECM No communication

WIRING DIAGRAM

A01HQPKE01

INSPECTION PROCEDURE

Note

Perform the universal trip to clear permanent DTCs Click here.

Tech Tips


  • Refer to inspection procedure for CAN communication system.

  • If the CAN communication malfunctions, the TCM cannot receive the current data from the ECM. In this case, the freeze frame data output from the TCM has not been updated, so the data will not be useful for the inspection. However, reading the Data List as the first step in troubleshooting is effective to find malfunctions.

  • The malfunction area can be checked using the Bus Check function on the Techstream Click here.

PROCEDURE


  1. CHECK ECU TERMINAL VOLTAGE (+B AND E1 TERMINALS)


    1. A01HP5ME67
      Text in Illustration
      *a

      Front view of wire harness connector

      (to TCM)

      Disconnect the TCM connector.

    2. Turn the engine switch on (IG).

    3. Measure the voltage according to the value(s) in the table below.

      Standard Voltage
      Tester Connection Switch Condition Specified Condition
      E7-18 (+B) - E7-8 (E1) Engine switch on (IG) 9 to 14 V

    4. Turn the engine switch off.

    5. Measure the resistance according to the value(s) in the table below.

      Standard Resistance
      Tester Connection Condition Specified Condition
      E7-8 (E1) - Body ground Always Below 1 Ω

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  2. CHECK HARNESS AND CONNECTOR (TCM - ECM)


    1. Disconnect the TCM connector.

    2. Disconnect the ECM connector.

    3. Measure the resistance according to the value(s) in the table below.

      Standard Resistance
      Tester Connection Condition Specified Condition
      E7-6 (CAN+) - E26-31 (CAN+) Always Below 1 Ω
      E7-7 (CAN-) - E26-1 (CAN-) Always Below 1 Ω
      E7-6 (CAN+) or E26-31 (CAN+) - Body ground and other terminals Always 10 kΩ or higher
      E7-7 (CAN-) or E26-1 (CAN-) - Body ground and other terminals Always 10 kΩ or higher

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  3. CHECK IF DTC OUTPUT RECURS


    1. Connect the Techstream to the DLC3.

    2. Clear the DTCs.

    3. Replace the TCM.

      Tech Tips

      Replace the TCM with a TCM from a normally functioning vehicle of the same model.

    4. Start the engine.

    5. Read the DTCs.

      Result
      Display (DTC Output) Proceed to
      U0100 A
      No DTC B

    B

    REPLACE TCM Click here

    A

    REPLACE ECM Click here