Dtc U0100/A2 Lost Communication With Ecm/Pcm A


DESCRIPTION

WIRING DIAGRAM

INSPECTION PROCEDURE

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

CHECK TCM (IG2 VOLTAGE, E1 GROUND)

CHECK WIRE HARNESS (ECM - TCM)

CONFIRM DTC

DTC U0100/A2 Lost Communication with ECM/PCM "A"


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 the intake air and 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 Code
DTC Detection Condition
Trouble Area
U0100/A2
No communication from ECM continues (1 trip detection logic)
  1. Open or short in TCM and ECM circuit
  2. TCM
  3. ECM

WIRING DIAGRAM


Toyota Fortuner. Ggn50, 60 Kun51, 61 Tgn51 Lan50.A340E Automatic Transmission.Automatic Transmission System. Dtc U0100/A2 Lost Communication With Ecm/Pcm A


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 moving or stationary, 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.
1.CHECK ECM (VC, +B VOLTAGE, E1 GROUND)
Toyota Fortuner. Ggn50, 60 Kun51, 61 Tgn51 Lan50.A340E Automatic Transmission.Automatic Transmission System. Dtc U0100/A2 Lost Communication With Ecm/Pcm A

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

    Standard Voltage:
    Tester Connection
    		Switch Condition
    		Specified Condition
    E4-1 (+B) - Body ground
    		Ignition switch ON
    		11 to 14 V
    E7-18 (VC) - Body ground
    		Ignition switch ON
    		4.5 to 5.5 V
    Standard Resistance:
    Tester Connection
    		Condition
    		Specified Condition
    E6-7 (E1) - Body ground
    		Always
    		Below 1 Ω


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


2.CHECK TCM (IG2 VOLTAGE, E1 GROUND)
Toyota Fortuner. Ggn50, 60 Kun51, 61 Tgn51 Lan50.A340E Automatic Transmission.Automatic Transmission System. Dtc U0100/A2 Lost Communication With Ecm/Pcm A

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

    Standard Voltage:
    Tester Connection
    		Switch Condition
    		Specified Condition
    T37-6 (IG2) - Body ground
    		Ignition switch ON
    		11 to 14 V
    Standard Resistance:
    Tester Connection
    		Condition
    		Specified Condition
    T19-1 (E1) - Body ground
    		Always
    		Below 1 Ω


NG
INSPECT IG2, E1 CIRCUIT (TCM POWER SOURCE CIRCUIT)
OK


3.CHECK WIRE HARNESS (ECM - TCM)
Toyota Fortuner. Ggn50, 60 Kun51, 61 Tgn51 Lan50.A340E Automatic Transmission.Automatic Transmission System. Dtc U0100/A2 Lost Communication With Ecm/Pcm A

  1. Disconnect the E5 ECM connector.

  1. Disconnect the T37 TCM connector.

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

    Standard Resistance:
    Tester Connection
    		Condition
    		Specified Condition
    E5-22 (CAN+) - T37-21 (CAN+)
    		Always
    		Below 1 Ω
    E5-21 (CAN-) - T37-20 (CAN-)
    		Always
    		Below 1 Ω
    E5-22 (CAN+) or T37-21 (CAN+) - Body ground
    		Always
    		10 kΩ or higher
    E5-21 (CAN-) or T37-20 (CAN-) - Body ground
    		Always
    		10 kΩ or higher


NG
REPAIR OR REPLACE HARNESS OR CONNECTOR
OK


4.CONFIRM DTC

  1. Clear the DTC.

  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.

    Result:
    Result
    		Proceed to
    U0100/A2 is output
    		A
    U0100/A2 is not output
    		B


B
REPLACE TCM
A

REPLACE ECM