GSIC - Global Service Information Center

### DTC U0001/A2 High Speed CAN Communication Bus

## for Preparation Click here

## DESCRIPTION

The Transmission Control Module (TCM) and ECM perform 2-way communications with each other via the Controller Area Network (CAN). The TCM sends signals to the ECM concerning required engine rpm, required engine torques, warning indicators in the combination meter, DTCs and other data. The ECM sends signals to the TCM concerning engine rpm, opening angles of the throttle valve, temperature of intake air, temperature of engine coolant, engine torques and other data.
If the TCM cannot communicate with the ECM, the TCM will conclude that there is a malfunction in the CAN system, illuminate the MIL and set a DTC.

DTC No. | DTC Detection Condition | Trouble Area

U0001/A2

No communication from TCM continues

1. Open or short in TCM and ECM circuit
2. TCM
3. ECM

## WIRING DIAGRAM

## INSPECTION PROCEDURE

HINT:

  Read freeze frame data using the intelligent tester. Freeze frame data records the engine conditions when a malfunction is detected. When troubleshooting, freeze frame data can help determine if the vehicle was running or stopped, if the engine was warmed up or not, and other data from the time the malfunction occurred.

NOTICE:

  If the ECM is replaced, the new ECM needs initialization (Click here).

1.CHECK ECM (VC, +B VOLTAGE, E1 GROUND)

1. Measure the voltage and resistance of the ECM connectors.

   Standard voltage:

     Tester Connection | Ignition Switch Position | Specified Condition
     E5-1 (+B) - Body ground | ON | 9 to 14 V
     E8-18 (VC) - Body ground | ON | 4.5 to 5.5 V

   Standard resistance:

     Tester Connection | Ignition Switch Position | Specified Condition
     E7-7 (E1) - Body ground | - | 10 kΩ or higher

| OK |

INSPECT +B, E1 CIRCUIT (ECM POWER SOURCE CIRCUIT OR VC CIRCUIT)

OK |

2.CHECK TCM (IG2 VOLTAGE, E1 GROUND)

1. Measure the voltage and resistance of the TCM connectors.

   Standard voltage:

     Tester Connection | Ignition Switch Position | Specified Condition
     T17-6 (IG2) - Body ground | ON | 9 to 14 V

   Standard resistance:

     Tester Connection | Ignition Switch Position | Specified Condition
     T19-1 (E1) - Body ground | - | 10 kΩ or higher

| NG |

INSPECT IG2 , E1 CIRCUIT (TCM POWER SOURCE CIRCUIT)

OK |

3.CHECK WIRE HARNESS (ECM - TCM)

1. Disconnect the E6 ECM connector.

1. Disconnect the T17 TCM connector.

1. Measure the resistance of the wire harness side connectors.

   Standard resistance:

     Tester Connection | Specified Condition
     E6-22 (CAN+) - T17-21 (CAN+) | Below 1 Ω
     E6-21 (CAN-) - T17-20 (CAN-) | Below 1 Ω
     E6-22 (CAN+) or T17-21 (CAN+) - Body ground | 10 kΩ or higher
     E6-21 (CAN-) or T17-20 (CAN-) - Body ground | 10 kΩ or higher

| NG |

REPAIR OR REPLACE HARNESS AND CONNECTOR

OK |

4.CHECK IF DTC OUTPUT RECURS

1. Clear the DTC (Click here).

1. Replace the TCM.

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

1. Start the engine.

1. Read the DTCs (Click here).

   Result:

     Display (DTC Output) | Proceed to
     U0001/A2 | A
     No DTC | B

| B |

REPLACE TCM

A |

REPLACE ECM