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

CLEAR DTC

(a) Clear the DTCs.

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2.	CHECK FOR DTC

(a) Check for DTCs.

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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

USE SIMULATION METHOD TO CHECK

3.	INSPECT UNLOCK WARNING SWITCH ASSEMBLY

(a) Remove the unlock warning switch assembly.

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(b) Inspect the unlock warning switch assembly.

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REPLACE UNLOCK WARNING SWITCH ASSEMBLY

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.

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

REPLACE TRANSPONDER KEY ECU ASSEMBLY

REPAIR OR REPLACE HARNESS OR CONNECTOR

Theft Deterrent System Presence Detection (B279C)

Antenna Coil Open / Short (B2784)

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