Circuit Operation with VD1 or UHT

The VD1 and UHT vehicles have 2 horn relays. One PCB relay integrated into the underhood fuse block and another removable relay mounted in the engine compartment. Battery positive voltage is applied at all times to both horn relay coils and the horn relay switches. Pressing the horn switch applies ground through the switch contacts and the horn relay control circuits to the coil side of the relays, energizing the relays. Battery voltage is then applied through the switch side of the relays through the horn control circuits to the horns. The body control module (BCM) may also apply ground to the horn relay control circuit as described above. The horns sound as long as ground is applied to the horn relay control circuit.