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


G036535E02


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)
A066060E37

  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)
G039048E02

  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)
G034917E02

  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