Horns operation (LHD)

HORNS OPERATION (LHD)

Non-airbag models Battery voltage is supplied from fuse 21 in the passenger compartment fuse box on a U/P wire directly to one side of the horn.

The other side of the horn receives an earth on the P/B wire via the slip ring and lighting switch when the horn switch is pressed.

NOTE: On some models, the alarm ECU will also supply an earth path directly to the horn on a P/B wire when the integrity of the alarm system is broken.

Airbag models The horn receives a direct earth on the B wire.

Battery voltage is supplied from fuse 21 in the passenger compartment fuse box on a U/P wire to one side of the horn relay coil and contacts. The other side of the relay coil receives an earth on the P/B wire from the horn push switch via different paths dependent on model.

NOTE: On some models, the alarm ECU will also supply an earth path to the horn relay coil on a P/B wire when the integrity of the alarm system is broken.

When the horn switch is pressed, an earth path is supplied to the horn relay coil on a P/B wire via the rotary coupler. This earths the relay coil, switching battery voltage from fuse 21 in the passenger compartment fuse box on the U/P wire via the closed contacts of the relay to the horn on the P/Y wire. Since the other side of the horn is connected to earth, the horn will sound.