LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Toyota >> 2013 >> Prius Two >> Repair and Diagnosis (Single Page) >> Accessories & Equipment >> Communication Devices >> Can Communication System (Diagnostic Codes & Symptom Tests) (Except Plug-In) >> Can Communication System >> DTC U1002: Lost Communication with Gateway Module (Parking Assist Bus) >> Procedure
April 5, 2026: LEMON Manuals is launched! Read the announcement.

DTC U1002: Lost Communication with Gateway Module (Parking Assist Bus): Procedure

  1. CHECK CAN BUS WIRE 
    1. Turn the power switch off.
    2. Measure the resistance according to the value(s) in the table below.
      Fig 1: Identifying Driving Support ECU Connector Terminals
      GTY225170Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

      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
      TEXT IN ILLUSTRATION

      *1 Component with harness connected
      (Driving Support ECU)
    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 B
      Short circuit between bus lines C
      • Ground short
      • +B short
      		 D

    B → See step   3 

    C → See step   6 

    D → See step   11 

    A: Go to next step 

  2. CHECK CAN BUS BRANCH WIRE (LANE RECOGNITION CAMERA SENSOR) 
    1. Check for a lane recognition camera sensor communication malfunction. Refer to DTC U1119: Lost Communication with Object Recognition ECU (CAN) .

    NG → REPAIR OR REPLACE CORRESPONDING ECU OR SENSOR WIRE OR CONNECTOR 

    OK → See step   13 

  3. CHECK FOR OPEN IN CAN BUS WIRE (DRIVING SUPPORT ECU) 
    1. Disconnect the driving support ECU connector.
      Fig 2: Identifying Driving Support ECU Connector Terminals
      GTY229798Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      TEXT IN ILLUSTRATION

      *1 Front view of wire harness connector
      (to Driving Support ECU)
    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 → See step   4 

    OK → See step   13 

  4. CHECK FOR OPEN IN CAN BUS WIRE (MILLIMETER WAVE RADAR SENSOR) 
    1. Reconnect the driving support ECU connector.
    2. Disconnect the millimeter wave radar sensor connector.
      Fig 3: Identifying A2 Millimeter Wave Radar Sensor Connector Open In CAN Bus Wire
      GTY232801Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      TEXT IN ILLUSTRATION

      *1 Front view of wire harness connector
      (to Millimeter Wave Radar Sensor)
    3. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

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

    NG → See step   5 

    OK → See step   14 

  5. CHECK FOR OPEN IN CAN BUS WIRE (CAN NO. 5 J/C) 
    1. Reconnect the millimeter wave radar sensor connector.
    2. Disconnect the CAN No. 5 junction connector.
      Fig 4: Identifying CAN No. 5 Junction Center Connector Terminals
      GTY221293Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      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
    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 main wire) B
      NG (to Millimeter wave radar sensor main wire) 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.
      Fig 5: Identifying Driving Support ECU Connector Terminals
      GTY229798Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      TEXT IN ILLUSTRATION

      *1 Front view of wire harness connector
      (to Driving Support ECU)
    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 → See step   7 

    OK → See step   13 

  7. CHECK FOR SHORT IN CAN BUS WIRES (MILLIMETER WAVE RADAR SENSOR) 
    1. Reconnect the driving support ECU connector.
    2. Disconnect the millimeter wave radar sensor connector.
      Fig 6: Identifying A2 Millimeter Wave Radar Sensor Connector Open In CAN Bus Wire
      GTY232801Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      TEXT IN ILLUSTRATION

      *1 Front view of wire harness connector
      (to Millimeter Wave Radar Sensor)
    3. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

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

    NG → See step   8 

    OK: Go to next step 

  8. CHECK FOR SHORT IN CAN BUS WIRES (CAN NO. 5 J/C MAIN WIRE) 
    1. Reconnect the millimeter wave radar sensor connector.
    2. Disconnect the CAN No. 5 junction connector.
      Fig 7: Identifying CAN No. 5 Junction Center Connector Terminals
      GTY221293Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      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
    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: Go to next step 

  9. CHECK FOR SHORT IN CAN BUS WIRES (LANE RECOGNITION CAMERA SENSOR BRANCH WIRE) 
    1. Disconnect the lane recognition camera sensor connector.
    2. Measure the resistance according to the value(s) in the table below.
      Fig 8: Identifying CAN No. 5 Junction Connector Terminals
      GTY221292Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

      Standard Resistance

      Tester Connection Switch Condition Specified Condition
      L102-2 (CANH) - L102-13 (CANL) Power switch off 1 MΩ or higher
      TEXT IN ILLUSTRATION

      *1 Front view of wire harness connector
      (to CAN No. 5 Junction Connector)
      *2 to Lane Recognition Camera Sensor

    NG → REPAIR OR REPLACE CAN BUS WIRE (LANE RECOGNITION CAMERA SENSOR BRANCH WIRE) 

    OK: Go to next step 

  10. CHECK CAN BUS WIRE (LANE RECOGNITION CAMERA SENSOR) 
    1. Reconnect the CAN No. 5 junction connector.
    2. Measure the resistance according to the value(s) in the table below.
      Fig 9: Identifying Driving Support ECU Connector Terminals
      GTY225169Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

      Standard Resistance

      Tester Connection Switch Condition Specified Condition
      L60-40 (CA1P) - L60-18 (CA1N) Power switch off 54 to 69 Ω
      TEXT IN ILLUSTRATION

      *1 Component with harness connected
      (Driving Support ECU)
      NOTE:
      • The resistance must be measured after the CAN No. 5 junction connector is reconnected.
      • The resistance must be measured after the lane recognition camera sensor connector is disconnected.

    NG → REPLACE CAN NO. 5 JUNCTION CONNECTOR 

    OK → See step   15 

  11. 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.
      Fig 10: Identifying L102 And L61 Connector Terminals
      GTY234318Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

      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
      L102-2 (CANH) - L61-4 (CG) Power switch off 200 Ω or higher Inspection for CANH ground short Lane recognition camera sensor
      L102-13 (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
      L102-2 (CANH) - L61-16 (BAT) Cable disconnected from negative (-) battery terminal 6 kΩ or higher Inspection for CANH +B short Lane recognition camera sensor
      L102-13 (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

      HINT: 

      • 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 Lane Recognition Camera Sensor
      *5 to Driving Support ECU - -

    NG → See step   12 

    OK → REPLACE CAN NO. 5 JUNCTION CONNECTOR 

  12. CHECK CAN BUS WIRE (ECU, SENSOR) 
    1. Disconnect the ECU or sensor connected to the CAN bus wire that is shorted to B+ or shorted to GND.

      HINT: 

      If the ECU or sensor has multiple connectors, disconnect the connector that includes the CAN bus wires. To determine the ECU or sensor that is connected to shorted bus wire, refer to Terminals of ECU tables. Refer to TERMINALS OF ECU .

    2. Measure the resistance according to the value(s) in the table below.
      Fig 11: Identifying Driving Support ECU Connector Terminals
      GTY225170Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

      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

      HINT: 

      • 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.
      TEXT IN ILLUSTRATION

      *1 Component with harness connected
      (Driving Support ECU)

    NG → REPAIR OR REPLACE CORRESPONDING ECU OR SENSOR WIRE OR CONNECTOR 

    OK → REPLACE CORRESPONDING ECU 

  13. REPLACE DRIVING SUPPORT ECU. Refer to  REMOVAL 
  14. REPLACE MILLIMETER WAVE RADAR SENSOR ASSEMBLY. Refer to  REMOVAL 
  15. REPLACE LANE RECOGNITION CAMERA SENSOR. Refer to  REMOVAL 
scientia non olet · About LEMON Manuals