Toyota Tundra Service Manual: Push Switch / Key Unlock Warning Switch Malfunction (B2780)

Toyota Tundra Service Manual / Vehicle Interior / Engine Immobiliser / Engine Immobiliser System (w/o Smart Key System) / Push Switch / Key Unlock Warning Switch Malfunction (B2780)

DESCRIPTION

This DTC is stored if the transponder key ECU assembly does not detect that the unlock warning switch assembly is on even when the ignition switch is ON.

DTC No.

Detection Item

DTC Detection Condition

Trouble Area

Note

B2780

Push Switch / Key Unlock Warning Switch Malfunction

The unlock warning switch assembly is not detected as being on when the ignition switch is ON (1 trip detection logic*).
  • Harness or connector
  • Unlock warning switch assembly
  • Transponder key ECU assembly
  • Insert the key into the ignition key cylinder.
  • *: Only output while a malfunction is present.
Vehicle Condition and Fail-safe Operation when Malfunction Detected

Vehicle Condition when Malfunction Detected

Fail-safe Operation when Malfunction Detected

Engine cannot be started

-
Related Data List and Active Test

DTC No.

Data List and Active Test

B2780

Key SW

WIRING DIAGRAM

CAUTION / NOTICE / HINT

NOTICE:

  • If the transponder key ECU assembly is replaced, refer to Registration.

    Click here

  • After repair, confirm that no DTCs are output by performing "DTC Output Confirmation Operation".

PROCEDURE

1.

CLEAR DTC

(a) Clear the DTCs.

Click here

NEXT

2.

CHECK FOR DTC

(a) Check for DTCs.

Click here

HINT:

Before checking for DTCs, perform the "DTC Output Confirmation Operation" procedure.

OK:

DTC B2780 is not output.

Result

Proceed to

B2780 is not output

A

B2780 is output

B
A

USE SIMULATION METHOD TO CHECK

B

3.

INSPECT UNLOCK WARNING SWITCH ASSEMBLY

(a) Remove the unlock warning switch assembly.

Click here

(b) Inspect the unlock warning switch assembly.

Click here

NG

REPLACE UNLOCK WARNING SWITCH ASSEMBLY

OK

4.

CHECK HARNESS AND CONNECTOR (UNLOCK WARNING SWITCH ASSEMBLY - TRANSPONDER KEY ECU ASSEMBLY AND BODY GROUND)

(a) Disconnect the J18 unlock warning switch assembly connector.

(b) Disconnect the J26 transponder key ECU assembly connector.

(c) Measure the resistance according to the value(s) in the table below.

Standard Resistance:

Tester Connection

Condition

Specified Condition

J18-1 - J26-3 (KSW)

Always

Below 1 Ω

J18-2 - Body ground

Always

Below 1 Ω

J18-1 - Body ground

Always

10 kΩ or higher

J26-3 (KSW) - Body ground

Always

10 kΩ or higher
OK

REPLACE TRANSPONDER KEY ECU ASSEMBLY

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR
    Theft Deterrent System Presence Detection (B279C)

    Antenna Coil Open / Short (B2784)

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