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HOMESERVICE MANUALSTOYOTA2013TUNDRA BASE, 5.7L ENG VIN WREPAIR AND DIAGNOSISBODY & FRAMEDOOR LOCKSENGINE IMMOBILISER SYSTEM (DIAGNOSTIC CODES & CIRCUIT TESTS)ENGINE IMMOBILIZER SYSTEMDTC B2780: PUSH SWITCH / KEY UNLOCK WARNING SWITCH MALFUNCTIONPROCEDURE
2013 Toyota Tundra Base, 5.7L Eng VIN W

DTC B2780: Push Switch / Key Unlock Warning Switch Malfunction: Procedure

2013 Toyota Tundra Base, 5.7L Eng VIN WSECTION Procedure
  1. CLEAR DTC 
    1. Clear the DTC. Refer to DTC CHECK / CLEAR .

    NEXT: Go to next step 

  2. CHECK FOR DTC 
    1. Check for DTC. Refer to DTC CHECK / CLEAR .

      OK

      DTC B2780 is not output.

    NG → See step   3 

    OK → See step   8 

  3. READ VALUE USING TECHSTREAM (UNLOCK WARNING SWITCH) 
    1. Use the Data List to check if the unlock warning switch is functioning properly.
      IMMOBILIZER

      Tester Display Measurement Item/Range Normal Condition Diagnostic Note
      Key SW Unlock warning switch signal / ON or OFF ON: Key is in ignition key cylinder
      OFF: No key is in ignition key cylinder      		 -

      OK

      ON (key is in ignition key cylinder) appears on the screen.

    NG → See step   4 

    OK → See step   9 

  4. INSPECT UNLOCK WARNING SWITCH 
    Fig 1: Identifying Unlock Warning Switch Connector Terminals
    GTY189189Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    1. Remove the unlock warning switch. Refer to REMOVAL .
    2. Measure the resistance according to the value(s) in the table below.

      Standard resistance

      Tester Connection Switch Condition Specified Condition
      1 - 2 Switch is pushed Below 1 Ω
      Switch is not pushed 10 kΩ or higher

    NG → See step   7 

    OK: Go to next step 

  5. CHECK HARNESS AND CONNECTOR (UNLOCK WARNING SWITCH - BODY GROUND) 
    Fig 2: Identifying J18 Switch Connector Terminals
    GTY184901Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    1. Disconnect the J18 switch connector.
    2. Measure the resistance according to the value(s) in the table below.

      Standard resistance

      Tester Connection Condition Specified Condition
      J18-2 - Body ground Always Below 1 Ω

    NG → REPAIR OR REPLACE HARNESS OR CONNECTOR 

    OK: Go to next step 

  6. CHECK HARNESS AND CONNECTOR (UNLOCK WARNING SWITCH - TRANSPONDER KEY ECU) 
    Fig 3: Checking Harness And Connector (Unlock Warning Switch -- Transponder Key ECU)
    GTY196160Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    1. Disconnect the J18 switch connector.
    2. Disconnect the J26 ECU connector.
    3. Measure the resistance according to the value(s) in the table below.

      Standard resistance

      Tester Connection Condition Specified Condition
      J26-3 (KSW) - J18-1 Always Below 1 Ω
      J26-3 (KSW) or J18-1 - Body ground Always 10 kΩ or higher

    NG → REPAIR OR REPLACE HARNESS OR CONNECTOR 

    OK → See step   9 

  7. REPLACE UNLOCK WARNING SWITCH. Refer to  REMOVAL 
  8. USE SIMULATION METHOD TO CHECK. Refer to  HOW TO PROCEED WITH TROUBLESHOOTING 
  9. REPLACE TRANSPONDER KEY ECU. Refer to  REMOVAL 
RENDER: 1.0x

NO RELATED

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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
  • • Brakes feel soft, pull hard to one side, or make grinding noises.
  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.