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DTC U1103: Lost Communication with Stop and Start Control Module: Procedure

  1. CHECK SUB BUS 15 
    1. Measure the resistance according to the value(s) in the table below.
      GTY410088Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

      Standard Resistance

      Tester Connection Condition Specified Condition Resistance: Malfunction
      A34-1 (CA3P) - A34-4 (CA3N) Cable disconnected from negative (-) battery terminal 54 to 69 Ω Below 53 Ω: Short in line
      A34-1 (CA3P) - A34-4 (CA3N) Cable disconnected from negative (-) battery terminal 54 to 69 Ω Higher than 70 Ω: Open in CAN main bus line
      A34-1 (CA3P) - A34-2 (+B) Cable disconnected from negative (-) battery terminal 6 kΩ or higher Below 6 kΩ: +B short
      A34-4 (CA3N) - A34-2 (+B) Cable disconnected from negative (-) battery terminal 6 kΩ or higher Below 6 kΩ: +B short
      A34-1 (CA3P) - A34-11 (E) Cable disconnected from negative (-) battery terminal 200 Ω or higher Below 200 Ω: Ground short
      A34-4 (CA3N) - A34-11 (E) Cable disconnected from negative (-) battery terminal 200 Ω or higher Below 200 Ω: Ground short
      TEXT IN ILLUSTRATION

      *a Component with harness connected
      (Certification ECU [Smart Key ECU Assembly])
      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 → See step   3 

    C → See step   6 

    A: Go to next step 

  2. CHECK FOR DTC OUTPUT 
    1. Clear the DTCs.
    2. Turn the engine switch off.
    3. Turn the engine switch on (IG) and recheck for DTCs.
      RESULT

      Result Proceed to
      U1002 is output from certification ECU (smart key ECU assembly) (Techstream display / Smart Access) A
      Other DTC is output B

    B → GO TO DIAGNOSIS PROCEDURE INDICATED BY OUTPUT DTC 

    A → See step   9 

  3. CHECK FOR OPEN IN CAN BUS LINES (CERTIFICATION ECU) 
    1. Disconnect the certification ECU (smart key ECU assembly) connector.
      GTY395909Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    2. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      A34-1 (CA3P) - A34-4 (CA3N) Cable disconnected from negative (-) battery terminal 108 to 132 Ω
      TEXT IN ILLUSTRATION

      *a Rear view of wire harness connector
      (to Certification ECU [Smart Key ECU Assembly])

    NG → See step   4 

    OK → See step   9 

  4. CHECK FOR OPEN IN CAN BUS LINES (NO. 8 JUNCTION CONNECTOR) 
    1. Reconnect the certification ECU (smart key ECU assembly) connector.
      GTY409347Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    2. Disconnect the wire harness connector from the No. 8 junction connector.
    3. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      A57-1 (CANH) - A57-12 (CANL) Cable disconnected from negative (-) battery terminal 108 to 132 Ω
      A57-2 (CANH) - A57-13 (CANL) Cable disconnected from negative (-) battery terminal 108 to 132 Ω
      TEXT IN ILLUSTRATION

      *a Rear view of wire harness connector
      (to No. 8 Junction Connector)
      *b to ECM
      *c to Certification ECU (Smart Key ECU Assembly)
      RESULT

      Result Proceed to
      OK A
      NG (to Certification ECU main bus line) B
      NG (to ECM main bus line) C

    B → REPAIR OR REPLACE CAN MAIN BUS LINE OR CONNECTOR (NO. 8 JUNCTION CONNECTOR - CERTIFICATION ECU) 

    C → See step   5 

    A → REPLACE NO. 8 JUNCTION CONNECTOR 

  5. CHECK FOR OPEN IN CAN BUS LINES (ECM) 
    1. Reconnect the wire harness connector from the No. 8 junction connector.
      GTY402108Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    2. Disconnect the ECM connector.
    3. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      A21-12 (CANP) - A12-11 (CANN) Cable disconnected from negative (-) battery terminal 108 to 132 Ω
      TEXT IN ILLUSTRATION

      *a Rear view of wire harness connector
      (to ECM)

    NG → REPAIR OR REPLACE CAN MAIN BUS LINE OR CONNECTOR (ECM - NO. 8 JUNCTION CONNECTOR) 

    OK → See step   10 

  6. CHECK FOR SHORT IN CAN BUS LINES (CERTIFICATION ECU) 
    1. Disconnect the certification ECU (smart key ECU assembly) connector.
      GTY400157Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    2. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      A34-1 (CA3P) - N20-4 (CG) Cable disconnected from negative (-) battery terminal 200 Ω or higher
      A34-4 (CA3N) - N20-4 (CG) Cable disconnected from negative (-) battery terminal 200 Ω or higher
      A34-1 (CA3P) - N20-16 (BAT) Cable disconnected from negative (-) battery terminal 6 kΩ or higher
      A34-4 (CA3N) - N20-16 (BAT) Cable disconnected from negative (-) battery terminal 6 kΩ or higher
      TEXT IN ILLUSTRATION

      *a Rear view of wire harness connector
      (to Certification ECU [Smart Key ECU Assembly])
      *b Front view of DLC3

    NG → See step   7 

    OK → See step   9 

  7. CHECK FOR SHORT IN CAN BUS LINES (NO. 8 JUNCTION CONNECTOR) 
    1. Reconnect the certification ECU (smart key ECU assembly) connector.
      GTY402679Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      TEXT IN ILLUSTRATION

      *a Rear view of wire harness connector
      (to No. 8 Junction Connector)      		 *b Front view of DLC3
      *c to ECM *d to Certification ECU (Smart Key ECU Assembly)
    2. Disconnect the wire harness connector from the No. 8 junction connector.
    3. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition Purpose Connected to
      A57-1 (CANH) - N20-4 (CG) Cable disconnected from negative (-) battery terminal 200 Ω or higher Inspection for CANH ground short ECM
      A57-12 (CANL) - N20-4 (CG) Cable disconnected from negative (-) battery terminal 200 Ω or higher Inspection for CANL ground short
      A57-2 (CANH) - N20-4 (CG) Cable disconnected from negative (-) battery terminal 200 Ω or higher Inspection for CANH ground short Certification ECU (smart key ECU assembly)
      A57-13 (CANL) - N20-4 (CG) Cable disconnected from negative (-) battery terminal 200 Ω or higher Inspection for CANL ground short
      A57-1 (CANH) - N20-16 (BAT) Cable disconnected from negative (-) battery terminal 6 kΩ or higher Inspection for CANH +B short ECM
      A57-12 (CANL) - N20-16 (BAT) Cable disconnected from negative (-) battery terminal 6 kΩ or higher Inspection for CANL +B short
      A57-2 (CANH) - N20-16 (BAT) Cable disconnected from negative (-) battery terminal 6 kΩ or higher Inspection for CANH +B short Certification ECU (smart key ECU assembly)
      A57-13 (CANL) - N20-16 (BAT) Cable disconnected from negative (-) battery terminal 6 kΩ or higher Inspection for CANL +B short
      RESULT

      Result Proceed to
      OK A
      NG (to Certification ECU main bus line) B
      NG (to ECM main bus line) C

    B → REPAIR OR REPLACE CAN MAIN BUS LINE OR CONNECTOR (NO. 8 JUNCTION CONNECTOR - CERTIFICATION ECU) 

    C → See step   8 

    A → REPLACE NO. 8 JUNCTION CONNECTOR 

  8. CHECK FOR SHORT IN CAN BUS LINES (ECM) 
    1. Disconnect the ECM connector.
      GTY409825Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    2. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      A21-12 (CANP) - N20-4 (CG) Cable disconnected from negative (-) battery terminal 200 Ω or higher
      A21-11 (CANN) - N20-4 (CG) Cable disconnected from negative (-) battery terminal 200 Ω or higher
      A21-12 (CANP) - N20-16 (BAT) Cable disconnected from negative (-) battery terminal 6 kΩ or higher
      A21-11 (CANN) - N20-16 (BAT) Cable disconnected from negative (-) battery terminal 6 kΩ or higher
      TEXT IN ILLUSTRATION

      *a Rear view of wire harness connector
      (to ECM)
      *b Front view of DLC3

    NG → REPAIR OR REPLACE CAN MAIN BUS LINE OR CONNECTOR (ECM - NO. 8 JUNCTION CONNECTOR) 

    OK → See step   10 

  9. REPLACE CERTIFICATION ECU (SMART KEY ECU ASSEMBLY). Refer to  REMOVAL [12/2011 - ] 
  10. REPLACE ECM. Refer to  REMOVAL [12/2011 - ] 
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