Low Beam Headlamps

When the headlamp switch is in the HEAD position it sends a ground signal to the BCM. The BCM receives the ground signal from the headlamp switch and then sends a ground signal to terminal 1 of the low beam relay. The headlamp switch also sends a redundant ground signal to terminal 1 of the low beam relay.

The low beam headlamps are controlled by the low beam relay (K131). The supply voltage for the coil side of the low beam relay is supplied from the BCM exterior lamp power circuit. The low beam relay coil is controlled by a ground from the BCM or the headlamp switch. When the BCM or the headlamp switch grounds terminal 1 of the low beam relay, the low beam relay coil is energized and the low beam relay internal switch closes.

The low beam relay has B+ supplied at all times to the switch side of the relay. When the low beam relay is energized, the internal switch closes and B+ is supplied to fuse #22 and fuse #31. Fuse #22 supplies B+ to the LH low beam headlamp and fuse #31 supplies B+ to the RH low beam headlamp. The LH and RH low beam headlamps are permanently grounded to G103. When B+ is applied to terminal C of the LH and RH low beam headlamps, both of the headlamps illuminate.