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DTC    U0104    Lost Communication with Driving Support ECU

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DESCRIPTION


DTC No.
DTC Detection Condition
Trouble Area
U0104
No communication from the driving support ECU continues.
  1. Driving support ECU branch wire or connector
  2. Power source circuit of driving support ECU
  3. Driving support ECU

HINT:
The diagnosis procedure is for when DTC U0104 is output by the power management control ECU (Intelligent tester display: Power Management1).


WIRING DIAGRAM


C210447E04


INSPECTION PROCEDURE

NOTICE:
  1. Turn the power switch off before measuring the resistances between CAN bus main wires and between CAN bus branch wires.
  2. Turn the power switch off before inspecting CAN bus wires for a ground short.
  3. After the power switch is turned off, check that the key reminder warning system and light reminder warning system are not operating.
  4. Before measuring the resistance, leave the vehicle as is for at least 1 minute and do not operate the power switch, any other switches or the doors. If any doors need to be opened in order to check connectors, open the doors and leave them open.

HINT:
  1. Operating the power switch, any other switches or a door triggers related ECU and sensor communication on the CAN. This communication will cause the resistance value to change.
  2. Even after DTCs are cleared, if a DTC is stored again after driving the vehicle for a while, the malfunction may be occurring due to vibration of the vehicle. In such a case, wiggling the ECUs or wire harness while performing the inspection below may help determine the cause of the malfunction.

1.RECONFIRM DTC OUTPUT

  1. Reconfirm DTCs.

    HINT:
    If CAN No. 2 bus DTC U1002 is output from the power the management control ECU (Intelligent tester display/Power Management1), troubleshoot for U1002 and check for malfunctions in the CAN No. 2 main bus circuit.

    Result:
    Result
    		Proceed to
    U1002 is not output from power management control ECU (Intelligent tester display/Power Management1)
    		A
    U1002 is output from power management control ECU (Intelligent tester display/Power Management1)
    		B



B
GO TO CIRCUITS INDICATED BY OUTPUT DTCS (Click here)
A


2.CHECK CAN BUS WIRE FOR DISCONNECTION (DRIVING SUPPORT ECU BRANCH WIRE)

  1. Turn the power switch off.



    E178930E18

  1. Disconnect the driving support ECU connector.

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

    Standard Resistance:
    Tester Connection
    		Switch Condition
    		Specified Condition
    L60-39 (CA2H) - L60-17 (CA2L)
    		Power switch off
    		54 to 69 Ω

    Text in Illustration 
    *1
    		Front view of wire harness connector
    (to Driving Support ECU)



NG
REPAIR OR REPLACE CAN BUS BRANCH WIRE OR CONNECTOR (DRIVING SUPPORT ECU BRANCH WIRE)
OK


3.CHECK HARNESS AND CONNECTOR (POWER SOURCE TERMINAL)

  1. Turn the power switch on (IG).



    E178930E19

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

    Standard Voltage:
    Tester Connection
    		Switch Condition
    		Specified Condition
    L60-30 (B) - Body ground
    		Power switch on (IG)
    		11 to 14 V

    Text in Illustration 
    *1
    		Front view of wire harness connector
    (to Driving Support ECU)



NG
REPAIR OR REPLACE HARNESS OR CONNECTOR (POWER SOURCE CIRCUIT)
OK


4.CHECK HARNESS AND CONNECTOR (GROUND TERMINAL)


    E178930E20

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

    Standard Resistance:
    Tester Connection
    		Condition
    		Specified Condition
    L60-25 (GND) - Body ground
    		Always
    		Below 1 Ω

    Text in Illustration 
    *1
    		Front view of wire harness connector
    (to Driving Support ECU)



NG
HARNESS OR CONNECTOR (GROUND CIRCUIT)
OK

REPLACE DRIVING SUPPORT ECU (Click here)