Possible causes

- Faulty unlock warning switch assembly
– Unlock warning switch assembly wWire harness

- Faulty transponder key ECU assembly

When is the code detected?

Unlock warning switch ON is not detected when ignition switch is ON.

B2780 TOYOTA Description

This Detected Trouble Code (DTC) will be output if the transponder key Electronic Control Unit (ECU) does not detect that the unlock warning switch is ON even when the ignition switch is ON (under normal condition, the unlock warning switch is ON when the ignition switch is ON).