GSIC - Global Service Information Center

### DTC B2780 Push Switch / Key Unlock Warning Switch Malfunction

## DESCRIPTION

This DTC will be output if the transponder key ECU does not detect that the unlock warning switch is ON even when the key is inserted into the ignition key cylinder. Under normal conditions, the unlock warning switch is ON when the key is inserted into the ignition key cylinder.

DTC No. | DTC Detection Condition | Trouble Area

B2780

Unlock warning switch ON is not detected when key is inserted into ignition key cylinder

1. Unlock warning switch assembly
2. Wire harness
3. Transponder key ECU assembly

## WIRING DIAGRAM

## INSPECTION PROCEDURE

1.READ VALUE OF INTELLIGENT TESTER (UNLOCK WARNING SWITCH ASSEMBLY)

1. Check the Data List for proper functioning of the unlock warning switch.

   Transponder key ECU assembly:
   Item | Measurement Item/Display (Range) | Normal Condition | Diagnostic Note
   Key SW | Unlock warning switch signal / ON or OFF | OFF: No key is in ignition key cylinder ON: Key is in ignition key cylinder | -

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

| OK |

REPLACE TRANSPONDER KEY ECU ASSEMBLY

NG |

2.INSPECT UNLOCK WARNING SWITCH ASSEMBLY

1. Remove the switch.

1. Measure the resistance of the switch.

   Standard resistance:

     Tester Connection | Switch Condition | Specified Condition
     1 - 2 | Pushed | Below 1 Ω
     Not pushed | 10 kΩ or higher

| NG |

REPLACE UNLOCK WARNING SWITCH ASSEMBLY

OK |

3.CHECK WIRE HARNESS (UNLOCK WARNING SWITCH - TRANSPONDER KEY ECU AND BODY GROUND)

1. Disconnect the U1 switch connector.

1. Disconnect the T21 ECU connector.

1. Measure the resistance of the wire harness side connectors.

   Standard resistance:

     Tester Connection | Specified Condition
     T21-3 (KSW) - U1-1 | Below 1 Ω
     U1-2 - Body ground | Below 1 Ω

| NG |

REPAIR OR REPLACE HARNESS AND CONNECTOR

OK |

REPLACE TRANSPONDER KEY ECU ASSEMBLY