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Home >> Lexus >> 2017 >> NX 300h >> Repair and Diagnosis (Single Page) >> Accessories & Equipment >> Communication Devices >> Can Communication System - Diagnostic Codes (1 Of 2) >> Can Communication System >> DTC U0100: Lost Communication with ECM / PCM "A"; DTC U0129: Lost Communication with Brake System Control Module; DTC U0293: Lost Communication with Hybrid Vehicle Control System [10/2014 - 09/2017] >> Procedure
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DTC U0100: Lost Communication with ECM / PCM "A"; DTC U0129: Lost Communication with Brake System Control Module; DTC U0293: Lost Communication with Hybrid Vehicle Control System [10/2014 - 09/2017]: Procedure

  1. CHECK FOR DTC 
    1. Check for DTCs.

      Powertrain > Hybrid Control > Trouble Codes 

      HINT: 

      If the hybrid vehicle control ECU outputs only DTC U0129, troubleshoot DTC U0129 and check the branch circuit of sub bus 15.

      Result

      Result Proceed to
      The hybrid vehicle control ECU outputs DTC U0129 and other DTCs. A
      The hybrid vehicle control ECU outputs only DTC U0129. B

    Result: 

    B 

    GO TO DIAGNOSIS PROCEDURE INDICATED BY OUTPUT DTC. Refer to  DTC U0129: Lost Communication with Brake System Control Module [10/2014 - 09/2017]  

    Result: 

    A 

    See step  2

  2. CHECK SUB BUS 15 
    1. Disconnect the cable from the negative (-) auxiliary battery terminal.
      GTY508458Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *a Component with harness connected
      (Hybrid Vehicle Control ECU)      		 *b Front view of DLC3
    2. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition Result
      I116-31 (CA3P) - I116-30 (CA3N) Cable disconnected from negative (-) auxiliary battery terminal 54 to 69 Ω Below 53 Ω: Short in line
      I116-31 (CA3P) - I116-30 (CA3N) Cable disconnected from negative (-) auxiliary battery terminal 54 to 69 Ω 70 Ω or higher: Open in CAN main bus line
      I116-31 (CA3P) - I7-4 (CG) Cable disconnected from negative (-) auxiliary battery terminal 200 Ω or higher Below 200 Ω: Ground short
      I116-30 (CA3N) - I7-4 (CG) Cable disconnected from negative (-) auxiliary battery terminal 200 Ω or higher Below 200 Ω: Ground short
      I116-31 (CA3P) - I7-16 (BAT) Cable disconnected from negative (-) auxiliary battery terminal 6 kΩ or higher Below 6 kΩ: +B short
      I116-30 (CA3N) - I7-16 (BAT) Cable disconnected from negative (-) auxiliary battery terminal 6 kΩ or higher Below 6 kΩ: +B short

      Result

      Result Proceed to
      OK A
      NG
      - Open in CAN main wire      		 B
      NG
      - Short in CAN bus wire      		 C
      NG
      - +B short
      - Ground short      		 D

    Result: 

    A 

    REPLACE HYBRID VEHICLE CONTROL ECU. Refer to  REMOVAL [10/2014 - 05/2019] 

    Result: 

    C 

    See step  8

    Result: 

    D 

    See step  15

    Result: 

    B 

    See step  3

  3. CHECK FOR OPEN IN CAN BUS MAIN WIRE (HYBRID VEHICLE CONTROL ECU) 
    1. Disconnect the hybrid vehicle control ECU connector.
      GTY503090Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *a Front view of wire harness connector
      (to Hybrid Vehicle Control ECU)
    2. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      I116-31 (CA3P) - I116-30 (CA3N) Cable disconnected from negative (-) auxiliary battery terminal 108 to 132 Ω

      Result

      Proceed to 
      OK
      NG

    Result: 

    OK 

    REPLACE HYBRID VEHICLE CONTROL ECU. Refer to  REMOVAL [10/2014 - 05/2019] 

    Result: 

    NG 

    See step  4

  4. CONNECT CONNECTOR 
    1. Reconnect the I116 hybrid vehicle control ECU connector.

      Result

      Proceed to 
      NEXT

    Result: 

    NEXT 

    See step  5

  5. CHECK FOR OPEN IN CAN BUS MAIN WIRE (NO. 1 CAN JUNCTION CONNECTOR) 
    1. Disconnect the No. 1 CAN junction connector.
      GTY513366Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *a Front view of wire harness connector
      (to No. 1 CAN Junction Connector)
      *b to Hybrid Vehicle Control ECU
      *c to ECM
    2. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition Connected to
      A63-2 (CANH) - A63-13 (CANL) Cable disconnected from negative (-) auxiliary battery terminal 108 to 132 Ω Hybrid Vehicle Control ECU
      A63-4 (CANH) - A63-15 (CANL) Cable disconnected from negative (-) auxiliary battery terminal 108 to 132 Ω ECM

      Result

      Result Proceed to
      OK A
      NG (to hybrid vehicle control ECU CAN main wire) B
      NG (to ECM CAN main wire) C

    Result: 

    A 

    REPLACE NO. 1 CAN JUNCTION CONNECTOR 

    Result: 

    B 

    REPAIR OR REPLACE CAN MAIN WIRE OR CONNECTOR (NO. 1 CAN JUNCTION CONNECTOR - HYBRID VEHICLE CONTROL ECU) 

    Result: 

    C 

    See step  6

  6. CONNECT CONNECTOR 
    1. Reconnect the A63 No. 1 CAN junction connector.

      Result

      Proceed to 
      NEXT

    Result: 

    NEXT 

    See step  7

  7. CHECK FOR OPEN IN CAN BUS MAIN WIRE (ECM) 
    1. Disconnect the ECM connector.
      GTY499603Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *a Front view of wire harness connector
      (to ECM)
    2. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      A35-12 (CANP) - A35-25 (CANN) Cable disconnected from negative (-) auxiliary battery terminal 108 to 132 Ω

      Result

      Proceed to 
      OK
      NG

    Result: 

    OK 

    REPLACE ECM. Refer to  REMOVAL [10/2014 - ] 

    Result: 

    NG 

    REPAIR OR REPLACE CAN MAIN WIRE OR CONNECTOR (NO. 1 CAN JUNCTION CONNECTOR - ECM) 

  8. CHECK FOR SHORT IN CAN BUS WIRES (HYBRID VEHICLE CONTROL ECU) 
    1. Disconnect the hybrid vehicle control ECU connector.
      GTY503090Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *a Front view of wire harness connector
      (to Hybrid Vehicle Control ECU)
    2. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      I116-31 (CA3P) - I116-30 (CA3N) Cable disconnected from negative (-) auxiliary battery terminal 108 to 132 Ω

      Result

      Proceed to 
      OK
      NG

    Result: 

    OK 

    REPLACE HYBRID VEHICLE CONTROL ECU. Refer to  REMOVAL [10/2014 - 05/2019] 

    Result: 

    NG 

    See step  9

  9. CONNECT CONNECTOR 
    1. Reconnect the I116 hybrid vehicle control ECU connector.

      Result

      Proceed to 
      NEXT

    Result: 

    NEXT 

    See step  10

  10. CHECK FOR SHORT IN CAN BUS WIRES (NO. 1 CAN JUNCTION CONNECTOR) 
    1. Disconnect the No. 1 CAN junction connector.
      GTY496845Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *a Front view of wire harness connector
      (to No. 1 CAN Junction Connector)
      *b to Brake Booster with Master Cylinder Assembly (Skid Control ECU)
      *c to Hybrid Vehicle Control ECU
      *d to ECM
    2. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition Connected to
      A63-1 (CANH) - A63-12 (CANL) Cable disconnected from negative (-) auxiliary battery terminal 108 to 132 Ω Brake Booster with Master Cylinder Assembly (Skid Control ECU)
      A63-2 (CANH) - A63-13 (CANL) Cable disconnected from negative (-) auxiliary battery terminal 200 Ω or higher Hybrid Vehicle Control ECU
      A63-4 (CANH) - A63-15 (CANL) Cable disconnected from negative (-) auxiliary battery terminal 108 to 132 Ω ECM

      Result

      Result Proceed to
      OK A
      NG (to hybrid vehicle control ECU CAN main wire) B
      NG (to ECM CAN main wire) C
      NG (to brake booster with master cylinder assembly [skid Control ECU] CAN branch wire) D

    Result: 

    A 

    REPLACE NO. 1 CAN JUNCTION CONNECTOR 

    Result: 

    B 

    REPAIR OR REPLACE CAN MAIN WIRE OR CONNECTOR (NO. 1 CAN JUNCTION CONNECTOR - HYBRID VEHICLE CONTROL ECU) 

    Result: 

    D 

    See step  13

    Result: 

    C 

    See step  11

  11. CONNECT CONNECTOR 
    1. Reconnect the A63 No. 1 CAN junction connector.

      Result

      Proceed to 
      NEXT

    Result: 

    NEXT 

    See step  12

  12. CHECK FOR SHORT IN CAN BUS WIRES (ECM) 
    1. Disconnect the ECM connector.
      GTY499604Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *a Front view of wire harness connector
      (to ECM)
    2. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      A35-12 (CANP) - A35-25 (CANN) Cable disconnected from negative (-) auxiliary battery terminal 108 to 132 Ω

      Result

      Proceed to 
      OK
      NG

    Result: 

    OK 

    REPLACE ECM. Refer to  REMOVAL [10/2014 - ] 

    Result: 

    NG 

    REPAIR OR REPLACE CAN MAIN WIRE OR CONNECTOR (NO. 1 CAN JUNCTION CONNECTOR - ECM) 

  13. CONNECT CONNECTOR 
    1. Reconnect the A63 No. 1 CAN junction connector.

      Result

      Proceed to 
      NEXT

    Result: 

    NEXT 

    See step  14

  14. CHECK FOR SHORT IN CAN BUS WIRES (SKID CONTROL ECU) 
    1. Disconnect the brake booster with master cylinder assembly (skid control ECU) connector.
      GTY515667Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *a Front view of wire harness connector
      (to Brake Booster with Master Cylinder Assembly [Skid Control ECU])
    2. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      A57-35 (CA2H) - A57-34 (CA2L) Cable disconnected from negative (-) auxiliary battery terminal 54 to 69 Ω

      Result

      Proceed to 
      OK
      NG

    Result: 

    OK 

    REPLACE BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY. Refer to  REMOVAL [10/2014 - 09/2015]  Refer to  REMOVAL [09/2015 - 05/2019] 

    Result: 

    NG 

    REPAIR OR REPLACE CAN BRANCH WIRE OR CONNECTOR (NO. 1 CAN JUNCTION CONNECTOR - SKID CONTROL ECU) 

  15. CHECK FOR SHORT IN CAN BUS WIRES (NO. 1 CAN JUNCTION CONNECTOR) 
    1. Disconnect the No. 1 CAN junction connector.
      GTY518549Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *a Rear view of wire harness connector
      (to No. 1 CAN Junction Connector)      		 *b Front view of DLC3
      *c to Brake Booster with Master Cylinder Assembly (Skid Control ECU) *d to Hybrid Vehicle Control ECU
      *e to ECM - -
    2. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition Purpose Connected to
      A63-1 (CANH) - I7-4 (CG) Cable disconnected from negative (-) auxiliary battery terminal 200 Ω or higher Inspection for CANH ground short Brake Booster with Master Cylinder Assembly (Skid Control ECU)
      A63-12 (CANL) - I7-4 (CG) Cable disconnected from negative (-) auxiliary battery terminal 200 Ω or higher Inspection for CANL ground short
      A63-1 (CANH) - I7-16 (BAT) Cable disconnected from negative (-) auxiliary battery terminal 6 kΩ or higher Inspection for CANH +B short
      A63-12 (CANL) - I7-16 (BAT) Cable disconnected from negative (-) auxiliary battery terminal 6 kΩ or higher Inspection for CANL +B short
      A63-2 (CANH) - I7-4 (CG) Cable disconnected from negative (-) auxiliary battery terminal 200 Ω or higher Inspection for CANH ground short Hybrid Vehicle Control ECU
      A63-13 (CANL) - I7-4 (CG) Cable disconnected from negative (-) auxiliary battery terminal 200 Ω or higher Inspection for CANL ground short
      A63-2 (CANH) - I7-16 (BAT) Cable disconnected from negative (-) auxiliary battery terminal 6 kΩ or higher Inspection for CANH +B short
      A63-13 (CANL) - I7-16 (BAT) Cable disconnected from negative (-) auxiliary battery terminal 6 kΩ or higher Inspection for CANL +B short
      A63-4 (CANH) - I7-4 (CG) Cable disconnected from negative (-) auxiliary battery terminal 200 Ω or higher Inspection for CANH ground short ECM
      A63-15 (CANL) - I7-4 (CG) Cable disconnected from negative (-) auxiliary battery terminal 200 Ω or higher Inspection for CANL ground short
      A63-4 (CANH) - I7-16 (BAT) Cable disconnected from negative (-) auxiliary battery terminal 6 kΩ or higher Inspection for CANH +B short
      A63-15 (CANL) - I7-16 (BAT) Cable disconnected from negative (-) auxiliary battery terminal 6 kΩ or higher Inspection for CANL +B short

      Result

      Result Proceed to
      OK A
      NG (to hybrid vehicle control ECU CAN main wire) B
      NG (to ECM CAN main wire) C
      NG (to brake booster with master cylinder assembly [skid Control ECU] CAN branch wire) D

    Result: 

    A 

    REPLACE NO. 1 CAN JUNCTION CONNECTOR 

    Result: 

    C 

    See step  18

    Result: 

    D 

    See step  20

    Result: 

    B 

    See step  16

  16. CONNECT CONNECTOR 
    1. Reconnect the A63 No. 1 CAN junction connector.

      Result

      Proceed to 
      NEXT

    Result: 

    NEXT 

    See step  17

  17. CHECK FOR SHORT IN CAN BUS WIRES (HYBRID VEHICLE CONTROL ECU) 
    1. Disconnect the hybrid vehicle control ECU connector.
      GTY517529Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *a Front view of wire harness connector
      (to Hybrid Vehicle Control ECU)
      *b Front view of DLC3
    2. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      I116-31 (CA3P) - I7-4 (CG) Cable disconnected from negative (-) auxiliary battery terminal 200 Ω or higher
      I116-30 (CA3N) - I7-4 (CG) Cable disconnected from negative (-) auxiliary battery terminal
      I116-31 (CA3P) - I7-16 (BAT) Cable disconnected from negative (-) auxiliary battery terminal 6 kΩ or higher
      I116-30 (CA3N) - I7-16 (BAT) Cable disconnected from negative (-) auxiliary battery terminal

      Result

      Proceed to 
      OK
      NG

    Result: 

    OK 

    REPLACE HYBRID VEHICLE CONTROL ECU. Refer to  REMOVAL [10/2014 - 05/2019] 

    Result: 

    NG 

    REPAIR OR REPLACE CAN MAIN WIRE OR CONNECTOR (HYBRID VEHICLE CONTROL ECU - NO. 1 CAN JUNCTION CONNECTOR) 

  18. CONNECT CONNECTOR 
    1. Reconnect the A63 No. 1 CAN junction connector.

      Result

      Proceed to 
      NEXT

    Result: 

    NEXT 

    See step  19

  19. CHECK FOR SHORT IN CAN BUS WIRES (ECM) 
    1. Disconnect the ECM connector.
      GTY510063Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *a Front view of wire harness connector
      (to ECM)
      *b Front view of DLC3
    2. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      A35-12 (CANP) - I7-4 (CG) Cable disconnected from negative (-) auxiliary battery terminal 200 Ω or higher
      A35-25 (CANN) - I7-4 (CG) Cable disconnected from negative (-) auxiliary battery terminal
      A35-12 (CANP) - I7-16 (BAT) Cable disconnected from negative (-) auxiliary battery terminal 6 kΩ or higher
      A35-25 (CANN) - I7-16 (BAT) Cable disconnected from negative (-) auxiliary battery terminal

      Result

      Proceed to 
      OK
      NG

    Result: 

    OK 

    REPLACE ECM. Refer to  REMOVAL [10/2014 - ] 

    Result: 

    NG 

    REPAIR OR REPLACE CAN MAIN WIRE OR CONNECTOR (ECM - NO. 1 CAN JUNCTION CONNECTOR) 

  20. CONNECT CONNECTOR 
    1. Reconnect the A63 No. 1 CAN junction connector.

      Result

      Proceed to 
      NEXT

    Result: 

    NEXT 

    See step  21

  21. CHECK FOR SHORT IN CAN BUS WIRES (SKID CONTROL ECU) 
    1. Disconnect the brake booster with master cylinder assembly (skid control ECU) connector.
      GTY517662Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *a Front view of wire harness connector
      (to Brake Booster with Master Cylinder Assembly [Skid Control ECU])
      *b Front view of DLC3
    2. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      A57-35 (CA2H) - I7-4 (CG) Cable disconnected from negative (-) auxiliary battery terminal 200 Ω or higher
      A57-34 (CA2L) - I7-4 (CG) Cable disconnected from negative (-) auxiliary battery terminal
      A57-35 (CA2H) - I7-16 (BAT) Cable disconnected from negative (-) auxiliary battery terminal 6 kΩ or higher
      A57-34 (CA2L) - I7-16 (BAT) Cable disconnected from negative (-) auxiliary battery terminal

      Result

      Proceed to 
      OK
      NG

    Result: 

    OK 

    REPLACE BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY. Refer to  REMOVAL [10/2014 - 09/2015]  Refer to  REMOVAL [09/2015 - 05/2019] 

    Result: 

    NG 

    REPAIR OR REPLACE CAN BRANCH WIRE OR CONNECTOR (SKID CONTROL ECU - NO. 1 CAN JUNCTION CONNECTOR) 

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