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

  • Driving support ECU

  • Millimeter wave radar sensor assembly

Tech Tips

The diagnosis procedure is for when DTC U1002 is output by the driving support ECU (GTS display: Pre-Crash 2).

WIRING DIAGRAM

A0041L9E05

INSPECTION PROCEDURE

Note


  • Turn the power switch off before measuring the resistances between CAN main bus wires and between CAN main 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. Disconnect the cable from the negative (-) auxiliary battery terminal.

    2. A0042D9E28
      Text in Illustration
      *a

      Component with harness connected

      (Driving Support ECU)

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

      Standard Resistance
      Tester Connection Condition Specified Condition Result
      L54-40 (CA1P) - L54-18 (CA1N) Cable disconnected from negative (-) auxiliary battery terminal 54 to 69 Ω

      Below 54 Ω:

      Short circuit between bus wires

      70 Ω or more:

      Open circuit in a main bus wire
      L54-40 (CA1P) - L54-25 (GND) Cable disconnected from negative (-) auxiliary battery terminal 200 Ω or higher

      Below 200 Ω:

      CANH ground short
      L54-18 (CA1N) - L54-25 (GND) Cable disconnected from negative (-) auxiliary battery terminal 200 Ω or higher

      Below 200 Ω:

      CANL ground short

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

      Standard Resistance
      Tester Connection Condition Specified Condition Result
      L54-40 (CA1P) - L54-30 (B) Cable disconnected from negative (-) auxiliary battery terminal 6 kΩ or higher

      Below 6 kΩ:

      CANH +B short
      L54-18 (CA1N) - L54-30 (B) Cable disconnected from negative (-) auxiliary battery terminal 6 kΩ or higher

      Below 6 kΩ:

      CANL +B short
      Result
      Result Proceed to
      OK A

      • Open circuit in CAN main bus wire

      • Short circuit between bus wires

      		 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 FOR POWER SOURCE CIRCUIT (MILLIMETER WAVE RADAR SENSOR ASSEMBLY)


    1. Check the millimeter wave radar sensor assembly power source circuit Click here.


    NG

    REPAIR OR REPLACE CORRESPONDING AREA

    OK

    REPLACE DRIVING SUPPORT ECU Click here

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


    1. A0042FJE05
      Text in Illustration
      *a

      Front view of wire harness connector

      (to Driving Support ECU)

      Disconnect the L54 driving support ECU connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      L54-40 (CA1P) - L54-18 (CA1N) Cable disconnected from negative (-) auxiliary battery terminal 108 to 132 Ω

    NG

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

    OK

    REPLACE DRIVING SUPPORT ECU Click here

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


    1. Reconnect the L54 driving support ECU connector.

    2. A00420IE05
      Text in Illustration
      *a

      Front view of wire harness connector

      (to Millimeter Wave Radar Sensor Assembly)

      Disconnect the A2 millimeter wave radar sensor assembly connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      A2-4 (CA1P) - A2-3 (CA1N) Cable disconnected from negative (-) auxiliary battery terminal 108 to 132 Ω

    NG

    REPAIR OR REPLACE CAN MAIN BUS WIRE (DRIVING SUPPORT ECU - MILLIMETER WAVE RADAR SENSOR ASSEMBLY)

    OK

    REPLACE MILLIMETER WAVE RADAR SENSOR ASSEMBLY Click here

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


    1. Disconnect the L54 driving support ECU connector.

    2. A0042FJE06
      Text in Illustration
      *a

      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 Condition Specified Condition Purpose
      L54-40 (CA1P) - L54-25 (GND) Cable disconnected from negative (-) auxiliary battery terminal 200 Ω or higher

      Below 200 Ω:

      CANH ground short
      L54-18 (CA1N) - L54-25 (GND) Cable disconnected from negative (-) auxiliary battery terminal 200 Ω or higher

      Below 200 Ω:

      CANL ground short
      L54-40 (CA1P) - L54-30 (B) Cable disconnected from negative (-) auxiliary battery terminal 6 kΩ or higher

      Below 6 kΩ:

      CANH +B short
      L54-18 (CA1N) - L54-30 (B) Cable disconnected from negative (-) auxiliary 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 ASSEMBLY) Click here

    OK

    REPLACE DRIVING SUPPORT ECU Click here

  6. CHECK CAN BUS WIRE (MILLIMETER WAVE RADAR SENSOR ASSEMBLY)


    1. Disconnect the A2 millimeter wave radar sensor assembly connector.

    2. A0041H9E10
      Text in Illustration
      *1 DLC3
      *a

      Front view of wire harness connector

      (to Millimeter Wave Radar Sensor Assembly)

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

      Standard Resistance
      Tester Connection Condition Specified Condition Purpose
      A2-4 (CA1P) - L55-4 (CG) Cable disconnected from negative (-) auxiliary battery terminal 200 Ω or higher

      Below 200 Ω:

      CANH ground short
      A2-3 (CA1N) - L55-4 (CG) Cable disconnected from negative (-) auxiliary battery terminal 200 Ω or higher

      Below 200 Ω:

      CANL ground short
      A2-4 (CA1P) - L55-16 (BAT) Cable disconnected from negative (-) auxiliary battery terminal 6 kΩ or higher

      Below 6 kΩ:

      CANH +B short
      A2-3 (CA1N) - L55-16 (BAT) Cable disconnected from negative (-) auxiliary 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

    REPAIR OR REPLACE CAN MAIN BUS WIRE (DRIVING SUPPORT ECU - MILLIMETER WAVE RADAR SENSOR ASSEMBLY)

    OK

    REPLACE MILLIMETER WAVE RADAR SENSOR ASSEMBLY Click here