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Home >> Lexus >> 2021 >> RC F Base >> Repair and Diagnosis (Single Page) >> Accessories & Equipment >> Communication Devices >> Can Communication System - Diagnostic Codes (1 Of 3) >> Can Communication System >> DTC U1002: Lost Communication with Gateway Module (Sensor Bus); DTC U0235: Lost Communication with Cruise Control Front Distance Range Sensor [09/2014 - 11/2017] >> Procedure

DTC U1002: Lost Communication with Gateway Module (Sensor Bus); DTC U0235: Lost Communication with Cruise Control Front Distance Range Sensor [09/2014 - 11/2017]: Procedure

  1. RECONFIRM DTC OUTPUT 
    1. Reconfirm DTCs.

      Body Electrical > Gateway > Trouble Codes 

      Result

      Result  Proceed to
      DTC U0104 not output from the network gateway ECU (Techstream display: Gateway) A
      DTC U0104 is output from the network gateway ECU (Techstream display: Gateway) B

    Result: 

    B 

    GO TO DIAGNOSTIC PROCEDURE INDICATED BY OUTPUT DTC. Refer to  DTC U0104: Lost Communication with Driving Support ECU [09/2014 - 11/2017]  

    Result: 

    A 

    See step  2

  2. CHECK SUB BUS 13 
    1. Turn the engine switch off.
    2. Disconnect the cable from the negative (-) battery terminal.
    3. Measure the resistance according to the value(s) in the table below.
      GTY498386Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *1 DLC3
      *a Component with harness connected
      (Driving Support ECU Assembly)

      Standard Resistance

      Tester Connection Condition Specified Condition Result
      Q1-40 (CA1P) - Q1-18 (CA1N) Cable disconnected from negative (-) battery terminal 54 to 69 Ω Below 54 Ω: Short circuit between bus lines
      70 Ω or more: Open circuit in main bus lines
      Q1-40 (CA1P) - Q1-25 (GND) Cable disconnected from negative (-) battery terminal 200 Ω or higher Below 200 Ω: CANH short to ground
      Q1-18 (CA1N) - Q1-25 (GND) Cable disconnected from negative (-) battery terminal 200 Ω or higher Below 200 Ω: CANL short to ground
      Q1-40 (CA1P) - O8-16 (BAT) Cable disconnected from negative (-) battery terminal 6 kΩ or higher Below 6 kΩ: CANH +B short
      Q1-18 (CA1N) - O8-16 (BAT) 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 lines B
      Short circuit between bus lines C
      • Short to ground
      • +B short
      		 D

    Result: 

    B 

    See step  7

    Result: 

    C 

    See step  9

    Result: 

    D 

    See step  11

    Result: 

    A 

    See step  3

  3. CHECK FOR POWER SOURCE CIRCUIT (MILLIMETER WAVE RADAR SENSOR ASSEMBLY) 
    1. Check the millimeter wave radar sensor assembly power source circuit.

      Refer to Millimeter Wave Radar Sensor Power Source Circuit [09/2014 - 11/2017]

      Result

      Result 
      OK
      NG

    Result: 

    NG 

    REPAIR OR REPLACE POWER SOURCE CIRCUIT (MILLIMETER WAVE RADAR SENSOR ASSEMBLY) 

    Result: 

    OK 

    See step  4

  4. CHECK FOR DTC OUTPUT 
    1. Reconnect the cable to the negative (-) battery terminal.
    2. Connect the Techstream to the DLC3.
    3. Turn the engine switch on (IG).
    4. Turn the Techstream on.
    5. Clear the DTCs.

      Body Electrical > Pre-Collision 2 > Trouble Codes 

    6. Turn the engine switch off.
    7. Turn the engine switch on (IG).
    8. Check for DTCs.

      Body Electrical > Pre-Collision 2 > Trouble Codes 

      Result

      Result  Proceed to
      DTC U1002 not output from the driving support ECU assembly (Techstream display: Pre-Collision 2) A
      DTC U1002 is output from the driving support ECU assembly (Techstream display: Pre-Collision 2) B

    Result: 

    A 

    SYMPTOM SIMULATION. Refer to  HOW TO PROCEED WITH TROUBLESHOOTING [09/2014 - 08/2016]  , or refer to  HOW TO PROCEED WITH TROUBLESHOOTING [08/2016 - 11/2017] 

    Result: 

    B 

    See step  5

  5. REPLACE DRIVING SUPPORT ECU ASSEMBLY 
    1. Replace the driving support ECU assembly.

      Refer to REMOVAL [09/2014 - 01/2023]

      Result

      Result 
      NEXT

    Result: 

    NEXT 

    See step  6

  6. CHECK FOR DTC OUTPUT 
    1. Reconnect the cable to the negative (-) battery terminal.
    2. Turn the engine switch off.
    3. Turn the engine switch on (IG).
    4. Check for DTCs.

      Body Electrical > Pre-Collision 2 > Trouble Codes 

      Result

      Result  Proceed to
      DTC U1002 is output from the driving support ECU assembly (Techstream display: Pre-Collision 2) A
      DTC U1002 not output from the driving support ECU assembly (Techstream display: Pre-Collision 2) B

    Result: 

    A 

    END 

    Result: 

    B 

    REPLACE MILLIMETER WAVE RADAR SENSOR ASSEMBLY. Refer to  REMOVAL [09/2014 - 11/2017] 

  7. CHECK FOR OPEN IN SUB BUS 13 MAIN LINES (DRIVING SUPPORT ECU ASSEMBLY) 
    1. Disconnect the Q1 driving support ECU assembly connector.
      GTY503857Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *a Front view of wire harness connector
      (to Driving Support ECU Assembly)
    2. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      Q1-40 (CA1P) - Q1-18 (CA1N) Cable disconnected from negative (-) battery terminal 108 to 132 Ω

      Result

      Result
      OK
      NG

    Result: 

    OK 

    REPLACE DRIVING SUPPORT ECU ASSEMBLY. Refer to  REMOVAL [09/2014 - 01/2023] 

    Result: 

    NG 

    See step  8

  8. CHECK FOR OPEN IN SUB BUS 13 MAIN LINES (MILLIMETER WAVE RADAR SENSOR ASSEMBLY) 
    1. Reconnect the Q1 driving support ECU assembly connector.
    2. Disconnect the B7 millimeter wave radar sensor assembly connector.
      GTY520214Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *a Front view of wire harness connector
      (to Millimeter Wave Radar Sensor Assembly)
    3. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      B7-3 (CA1P) - B7-2 (CA1N) Cable disconnected from negative (-) battery terminal 108 to 132 Ω

      Result

      Result
      OK
      NG

    Result: 

    OK 

    REPLACE MILLIMETER WAVE RADAR SENSOR ASSEMBLY. Refer to  REMOVAL [09/2014 - 11/2017] 

    Result: 

    NG 

    REPAIR OR REPLACE CAN MAIN BUS LINES OR CONNECTOR 

  9. CHECK FOR SHORT IN SUB BUS 13 LINES (DRIVING SUPPORT ECU ASSEMBLY) 
    1. Disconnect the Q1 driving support ECU assembly connector.
      GTY503864Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *a Front view of wire harness connector
      (to Driving Support ECU Assembly)
    2. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      Q1-40 (CA1P) - Q1-18 (CA1N) Cable disconnected from negative (-) battery terminal 108 to 132 Ω

      Result

      Result
      OK
      NG

    Result: 

    OK 

    REPLACE DRIVING SUPPORT ECU ASSEMBLY. Refer to  REMOVAL [09/2014 - 01/2023] 

    Result: 

    NG 

    See step  10

  10. CHECK FOR SHORT IN SUB BUS 13 LINES (MILLIMETER WAVE RADAR SENSOR ASSEMBLY) 
    1. Reconnect the Q1 driving support ECU assembly connector.
    2. Disconnect the B7 millimeter wave radar sensor assembly connector.
      GTY509833Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *a Front view of wire harness connector
      (to Millimeter Wave Radar Sensor Assembly)
    3. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      B7-3 (CA1P) - B7-2 (CA1N) Cable disconnected from negative (-) battery terminal 108 to 132 Ω

      Result

      Result
      OK
      NG

    Result: 

    OK 

    REPLACE MILLIMETER WAVE RADAR SENSOR ASSEMBLY. Refer to  REMOVAL [09/2014 - 11/2017] 

    Result: 

    NG 

    REPAIR OR REPLACE CAN MAIN BUS LINES OR CONNECTOR 

  11. CHECK FOR SHORT IN SUB BUS 13 LINE (DRIVING SUPPORT ECU ASSEMBLY) 
    1. Disconnect the Q1 driving support ECU assembly connector.
    2. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition Result
      Q1-40 (CA1P) - Q1-25 (GND) Cable disconnected from negative (-) battery terminal 200 Ω or higher Below 200 Ω: CANH short to ground
      Q1-18 (CA1N) - Q1-25 (GND) Cable disconnected from negative (-) battery terminal 200 Ω or higher Below 200 Ω: CANL short to ground
      Q1-40 (CA1P) - O8-16 (BAT) Cable disconnected from negative (-) battery terminal 6 kΩ or higher Below 6 kΩ: CANH +B short
      Q1-18 (CA1N) - O8-16 (BAT) Cable disconnected from negative (-) battery terminal 6 kΩ or higher Below 6 kΩ: CANL +B short
      GTY520309Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *1 DLC3
      *a Front view of wire harness connector
      (to Driving Support ECU Assembly)

      HINT: 

      • It is only necessary to perform the inspection in the above table for the result (short circuit) that was obtained in the Check Sub Bus 13 inspection.
      • Find the necessary inspection from the Result column that matches the result in the Result column from the Check Sub Bus 13 inspection.

      Result

      Result
      OK
      NG

    Result: 

    OK 

    REPLACE DRIVING SUPPORT ECU ASSEMBLY. Refer to  REMOVAL [09/2014 - 01/2023] 

    Result: 

    NG 

    See step  12

  12. CHECK FOR SHORT IN SUB BUS 13 LINE (MILLIMETER WAVE RADAR SENSOR ASSEMBLY) 
    1. Reconnect the Q1 driving support ECU assembly connector.
    2. Disconnect the B7 millimeter wave radar sensor assembly connector.
      GTY511441Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *1 DLC3
      *a Front view of wire harness connector
      (to Millimeter Wave Radar Sensor Assembly)
    3. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition Result
      B7-3 (CA1P) - O8-4 (CG) Cable disconnected from negative (-) battery terminal 200 Ω or higher Below 200 Ω: CANH short to ground
      B7-2 (CA1N) - O8-4 (CG) Cable disconnected from negative (-) battery terminal 200 Ω or higher Below 200 Ω: CANL short to ground
      B7-3 (CA1P) - O8-16 (BAT) Cable disconnected from negative (-) battery terminal 6 kΩ or higher Below 6 kΩ: CANH +B short
      B7-2 (CA1N) - O8-16 (BAT) 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 Sub Bus 13 inspection.
      • Find the necessary inspection from the Result column that matches the result in the Result column from the Check Sub Bus 13 inspection.

      Result

      Result
      OK
      NG

    Result: 

    OK 

    REPLACE MILLIMETER WAVE RADAR SENSOR ASSEMBLY. Refer to  REMOVAL [09/2014 - 11/2017] 

    Result: 

    NG 

    REPAIR OR REPLACE CAN MAIN BUS LINE OR CONNECTOR 

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