CAN COMMUNICATION SYSTEM, Diagnostic DTC:U1002

DTC Code DTC Name
U1002 Lost Communication with Gateway Module (Parking Assist Bus)

DESCRIPTION

The driving support ECU will store this DTC when no signals can be received from the ECUs that have been memorized as those that are connected to the parking assist bus.

DTC No. DTC Detection Condition Trouble Area
U1002 Driving support ECU cannot receive signals from all ECUs that have been memorized as those connected to the parking assist bus.

  • Open or short in parking assist bus main wire or connector

  • Open or short in parking assist bus branch wire or connector

  • Driving support ECU

  • CAN No. 5 junction connector

Tech Tips

The diagnosis procedure is for when DTC U1002 is output by the driving support ECU (Intelligent tester display: Pre-Crash2).

WIRING DIAGRAM

A01JBHYE01

INSPECTION PROCEDURE

Note


  • Turn the power switch off before measuring the resistances between CAN bus main wires and between CAN bus branch wires.

  • Turn the power switch off before inspecting CAN bus wires for a ground short.

  • After the power switch is turned off, check that the key reminder warning system and light reminder warning system are not operating.

  • 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.

Tech Tips


  • 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.

  • 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.

PROCEDURE


  1. CHECK CAN BUS WIRE


    1. Turn the power switch off.

    2. A01J8IAE12
      Text in Illustration
      *1

      Component with harness connected

      (Driving Support ECU)

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

      Standard Resistance
      Tester Connection Switch Condition Specified Condition Result
      L60-40 (CA1P) - L60-18 (CA1N) Power switch off 54 to 69 Ω

      Below 54 Ω:

      Short circuit between bus lines

      70 Ω or more:

      Open circuit in a main bus line
      L60-40 (CA1P) - L60-25 (GND) Power switch off 200 Ω or higher

      Below 200 Ω:

      CANH ground short
      L60-18 (CA1N) - L60-25 (GND) Power switch off 200 Ω or higher

      Below 200 Ω:

      CANL ground short

    3. Disconnect the cable from the negative (-) battery terminal.

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

      Standard Resistance
      Tester Connection Condition Specified Condition Result
      L60-40 (CA1P) - L60-30 (B) Cable disconnected from negative (-) battery terminal 6 kΩ or higher

      Below 6 kΩ:

      CANH +B short
      L60-18 (CA1N) - L60-30 (B) Cable disconnected from negative (-) battery terminal 6 kΩ or higher

      Below 6 kΩ:

      CANL +B short
      Result
      Result Proceed to
      OK A

      • Open circuit in CAN main bus line

      • Short circuit between bus lines

      		 B

      • Ground short

      • +B short

      		 C

    B

    CHECK FOR OPEN IN CAN BUS WIRE (DRIVING SUPPORT ECU) Click here

    C

    CHECK FOR SHORT IN CAN BUS WIRES (DRIVING SUPPORT ECU) Click here

    A

  2. CHECK CAN BUS BRANCH WIRE (MILLIMETER WAVE RADAR SENSOR)


    1. Check for a millimeter wave radar sensor communication malfunction Click here.


    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

    REPLACE DRIVING SUPPORT ECU Click here

  3. CHECK FOR OPEN IN CAN BUS WIRE (DRIVING SUPPORT ECU)


    1. A01J93RE21
      Text in Illustration
      *1

      Front view of wire harness connector

      (to Driving Support ECU)

      Disconnect the driving support ECU connector.

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

      Standard Resistance
      Tester Connection Switch Condition Specified Condition
      L60-40 (CA1P) - L60-18 (CA1N) Power switch off 108 to 132 Ω

    NG

    CHECK FOR OPEN IN CAN BUS WIRE (MILLIMETER WAVE RADAR SENSOR) Click here

    OK

    REPLACE DRIVING SUPPORT ECU Click here

  4. CHECK FOR OPEN IN CAN BUS WIRE (MILLIMETER WAVE RADAR SENSOR)


    1. Reconnect the driving support ECU connector.

    2. A01J9FEE01
      Text in Illustration
      *1

      Front view of wire harness connector

      (to Millimeter Wave Radar Sensor)

      Disconnect the millimeter wave radar sensor connector.

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

      Standard Resistance
      Tester Connection Switch Condition Specified Condition
      A2-4 (CA1P) - A1-3 (CA1N) Power switch off 108 to 132 Ω

    NG

    CHECK FOR OPEN IN CAN BUS WIRE (CAN NO. 5 J/C) Click here

    OK

    REPLACE MILLIMETER WAVE RADAR SENSOR ASSEMBLY Click here

  5. CHECK FOR OPEN IN CAN BUS WIRE (CAN NO. 5 J/C)


    1. Reconnect the millimeter wave radar sensor connector.

    2. A01JAQEE24
      Text in Illustration
      *1

      Front view of wire harness connector

      (to CAN No. 5 Junction Connector)
      *2 to Millimeter Wave Radar Sensor
      *3 to Driving Support ECU

      Disconnect the CAN No. 5 junction connector.

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

      Standard Resistance
      Tester Connection Switch Condition Specified Condition Connected to
      L102-1 (CANH) - L102-12 (CANL) Power switch off 108 to 132 Ω Millimeter wave radar sensor
      L102-3 (CANH) - L102-14 (CANL) Power switch off 108 to 132 Ω Driving support ECU
      Result
      Result Proceed to
      OK A
      NG (to driving support ECU) B
      NG (to millimeter wave radar sensor) C

    B

    REPAIR OR REPLACE CAN BUS MAIN WIRE (CAN NO. 5 J/C - DRIVING SUPPORT ECU)

    C

    REPAIR OR REPLACE CAN BUS MAIN WIRE (CAN NO. 5 J/C - MILLIMETER WAVE RADAR SENSOR)

    A

    REPLACE CAN NO. 5 JUNCTION CONNECTOR

  6. CHECK FOR SHORT IN CAN BUS WIRES (DRIVING SUPPORT ECU)


    1. Disconnect the driving support ECU connector.

    2. A01J93RE30
      Text in Illustration
      *1

      Front view of wire harness connector

      (to Driving Support ECU)

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

      Standard Resistance
      Tester Connection Switch Condition Specified Condition Purpose
      L60-40 (CA1P) - L60-25 (GND) Power switch off 200 Ω or higher

      Below 200 Ω:

      CANH ground short
      L60-18 (CA1N) - L60-25 (GND) Power switch off 200 Ω or higher

      Below 200 Ω:

      CANL ground short
      L60-40 (CA1P) - L60-30 (B) Cable disconnected from negative (-) battery terminal 6 kΩ or higher

      Below 6 kΩ:

      CANH +B short
      L60-18 (CA1N) - L60-30 (B) Cable disconnected from negative (-) battery terminal 6 kΩ or higher

      Below 6 kΩ:

      CANL +B short

      Tech Tips


      • It is only necessary to perform the inspection in the above table for the result (short circuit) that was obtained in the Check CAN Bus Wire inspection.

        Find the necessary inspection from the Purpose column that matches the result in the Result column from the Check CAN Bus Wire inspection.

      • If the resistance changes to normal when the connector is disconnected from the ECU, there may be a short in the ECU.


    NG

    CHECK CAN BUS WIRE (MILLIMETER WAVE RADAR SENSOR) Click here

    OK

    REPLACE DRIVING SUPPORT ECU Click here

  7. CHECK CAN BUS WIRE (MILLIMETER WAVE RADAR SENSOR)


    1. Disconnect the millimeter wave radar sensor connector.

    2. A01J9CSE01
      Text in Illustration
      *1

      Front view of wire harness connector

      (to Millimeter Wave Radar Sensor)
      *2 DLC3

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

      Standard Resistance
      Tester Connection Switch Condition Specified Condition Purpose
      A2-4 (CA1P) - L61-4 (CG) Power switch off 200 Ω or higher

      Below 200 Ω:

      CANH ground short
      A2-3 (CA1N) - L61-4 (CG) Power switch off 200 Ω or higher

      Below 200 Ω:

      CANL ground short
      A2-4 (CA1P) - L61-16 (BAT) Cable disconnected from negative (-) battery terminal 6 kΩ or higher

      Below 6 kΩ:

      CANH +B short
      A2-3 (CA1N) - L61-16 (BAT) Cable disconnected from negative (-) battery terminal 6 kΩ or higher

      Below 6 kΩ:

      CANL +B short

      Tech Tips


      • It is only necessary to perform the inspection in the above table for the result (short circuit) that was obtained in the Check CAN Bus Wire inspection.

        Find the necessary inspection from the Purpose column that matches the result in the Result column from the Check CAN Bus Wire inspection.

      • If the resistance changes to normal when the connector is disconnected from the ECU, there may be a short in the ECU.


    NG

    CHECK CAN BUS WIRE (CAN NO. 5 J/C) Click here

    OK

    REPLACE MILLIMETER WAVE RADAR SENSOR ASSEMBLY Click here

  8. CHECK CAN BUS WIRE (CAN NO. 5 J/C)


    1. Disconnect the CAN No. 5 junction connector.

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

      A01JDACE15
      Standard Resistance
      Tester Connection Condition Specified Condition Purpose Connected to
      L102-1 (CANH) - L61-4 (CG) Power switch off 200 Ω or higher Inspection for CANH ground short Millimeter wave radar sensor
      L102-12 (CANL) - L61-4 (CG) Power switch off 200 Ω or higher Inspection for CANL ground short
      L102-3 (CANH) - L61-4 (CG) Power switch off 200 Ω or higher Inspection for CANH ground short Driving support ECU
      L102-14 (CANL) - L61-4 (CG) Power switch off 200 Ω or higher Inspection for CANL ground short
      L102-1 (CANH) - L61-16 (BAT) Cable disconnected from negative (-) battery terminal 6 kΩ or higher Inspection for CANH +B short Millimeter wave radar sensor
      L102-12 (CANL) - L61-16 (BAT) Cable disconnected from negative (-) battery terminal 6 kΩ or higher Inspection for CANL +B short
      L102-3 (CANH) - L61-16 (BAT) Cable disconnected from negative (-) battery terminal 6 kΩ or higher Inspection for CANH +B short Driving support ECU
      L102-14 (CANL) - L61-16 (BAT) Cable disconnected from negative (-) battery terminal 6 kΩ or higher Inspection for CANL +B short

      Tech Tips


      • It is only necessary to perform the inspection in the above table for the result (short circuit) that was obtained in the Check CAN Bus Wire inspection.

      • Find the necessary inspection from the Purpose column that matches the result in the Result column from the Check CAN Bus Wire inspection.

      Text in Illustration
      *1

      Front view of wire harness connector

      (to CAN No. 5 Junction Connector)

      		 *2 DLC3
      *3 to Millimeter Wave Radar Sensor *4 to Driving Support ECU
      Result
      Result Proceed to
      OK A
      NG (to driving support ECU) B
      NG (to millimeter wave radar sensor) C

    B

    REPAIR OR REPLACE CAN BUS MAIN WIRE (CAN NO. 5 J/C - DRIVING SUPPORT ECU)

    C

    REPAIR OR REPLACE CAN BUS MAIN WIRE (CAN NO. 5 J/C - MILLIMETER WAVE RADAR SENSOR)

    A

    REPLACE CAN NO. 5 JUNCTION CONNECTOR