B2780 Unlock warning switch on is not detected when ignition switch is on

DESCRIPTION

This DTC will be output if the transponder key ECU does not detect that the unlock warning switch is on even when the ignition switch is on (Under the normal conditions, the unlock warning switch is on when the ignition switch is on).

DTC No.	DTC Detection Condition	Trouble Area
B2780	Unlock warning switch on is not detected when ignition switch is on	Unlock warning switch assembly Wire harness Transponder key ECU assembly

WIRING DIAGRAM

INSPECTION PROCEDURE

1. READ VALUE OF INTELLIGENT TESTER

1. Connect the intelligent tester to the DLC3.

2. Turn the ignition switch on and turn the intelligent tester main switch on.

3. Select Key SW in the DATA LIST and read the value displayed on the intelligent tester.

   Transponder key ECU: 

   Item	Measurement Item/Display (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:

   Both ON (Key is in ignition key cylinder) and OFF (No key in ignition key cylinder) appear on the screen.
   

OK	REPLACE TRANSPONDER KEY ECU ASSEMBLY

NG

2. INSPECT UNLOCK WARNING SWITCH ASSEMBLY

1. Remove the unlock warning switch.

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

   Resistance:

   Tester Connection	Switch Condition	Specified Condition
   1 - 2	Switch pushed (Key set)	Below 1 Ω
   	Switch free (Key removed)	10 kΩ or higher

NG	REPLACE UNLOCK WARNING SWITCH ASSEMBLY

OK

3. CHECK HARNESS AND CONNECTOR (TRANSPONDER KEY ECU ASSEMBLY - UNLOCK WARNING SW ASSEMBLY)

1. Disconnect the T8 ECU and K6 switch connectors.

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

   Resistance:

   Tester Connection	Specified Condition
   T8-3 (KSW) - K6-2	Below 1 Ω
   T8-3 (KSW) - Body ground	10 kΩ or higher

NG	REPAIR OR REPLACE HARNESS OR CONNECTOR

OK

4. CHECK HARNESS AND CONNECTOR (UNLOCK WARNING SW ASSEMBLY - BODY GROUND)

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

   Resistance:

   Tester Connection	Specified Condition
   K6-1 - Body ground	Below 1 Ω

NG	REPAIR OR REPLACE HARNESS OR CONNECTOR

OK
REPLACE TRANSPONDER KEY ECU ASSEMBLY