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.

The high beam headlamps are illuminated when all of the following relays are energized by the BCM.

1. Daytime running lamps (DRL) relay K151
2. Headlamp relay , LH (high beam) K133
3. Headlamp relay , RH (high beam) K132

The daytime running lamp relay K151 has B+ supplied at all times to the switch side of the relay. When the daytime running lamp relay is energized by the BCM, the relay internal switch closes and B+ is supplied to the LH headlamp. The LH headlamp relay K133 has ground supplied at all times to the switch side of the relay. When the LH headlamp Relay K133 is energized by the BCM, ground is supplied to the LH headlamp and it illuminates.

The RH headlamp relay K132 has B+ supplied at all times to the switch side of the relay. When the RH headlamp relay K132 is energized by the BCM, the relay internal switch closes and B+ is supplied to the RH headlamp. The RH headlamp is grounded at all times by G103 and the RH headlamp illuminates.

The BCM will energize the RH and LH headlamp relays and the daytime running lamp relay when the BCM receive B+ from the turn signal switch (high beam switch). The LO BEAM Fuse supplies voltage to the turn signal switch only when the low beam headlamps are on. When the turn signal lever is pushed forward, the turn signal switch sends B+ to the BCM. When the BCM receives B+ from the turn signal switch, it then sends a ground signal to the daytime running lamp relay K151 and the LH and RH headlamp relays. The coil side of the relays have B+ supplied to them at all times and the relays energize, closing the internal switch contacts.

When the ignition switch is in the ON position and the wipers have been turned on for approximately 20 seconds, the BCM will turn on the low beam headlamps and the park lamps. The low beam headlamps and the park lamps will turn off approximately 20 seconds after the wipers have been turned off. If the ignition switch is turned to the LOCK position, the low beam headlamps and the park lamps will immediately be turned off.