Circuit breaker 14 applies voltage to all of the filaments of the left headlamp at all times through CKT 688 or CKT 689 (RED/YEL). Circuit breaker 15 applies voltage to all of the filaments of the right headlamp at all times through CKT 694 or CKT 695 (RED/WHT). The headlamp switch is grounded at all times through CKT 87 and CKT 86 (BLK) to G105.

When you place the headlamp switch in the HEAD and LO positions, the internal contacts of the switch close. This provides a path to ground the coil of the lighting relay through CKT 717 (RED/BLK). Circuit breaker 16 applies voltage at all times to the other side of the lighting relay coil. When ground is provided, the relay energizes, switching the relay contacts. A ground path is now provided to the low beam filaments through CKT 691 or CKT 697 (RED/BLK), through the now closed contacts of the relay, through CKT 716 (YEL) to the closed contacts of the lighting high/low relay to G105. With ground provided, the low beam filaments illuminate.

When the headlamp switch is in the HI or PASS position, a ground path to the lighting high/low relay is provided through CKT 721 (RED/YEL). Voltage is applied at all times through circuit breaker 16 and CKT 719 (ORN) to the coil of the lighting high/low relay, causing the relay to energize. With the relay contacts switched, a ground path is provided to the high beam filaments through CKT 690, CKT 692, CKT 696 or CKT 697 (BLK/WHT) through the now closed contacts of the lighting high/low relay to G105. With ground provided, the high beam filaments illuminate.

In DRL operation, ground is provided to the low beam filaments through a different circuit through the normally closed contacts of the lighting relay. The park brake switch is grounded at all times at G105. When the parking brake is disengaged, ground is provided to one of the contacts of the DRL Off relay. The DRL Off relay is permanently grounded at G105. When the ignition switch is in the RUN position, voltage is supplied to the other side of the DRL Off relay, causing the relay to energize. The ground path is now provided through the now closed contacts of the DRL Off relay through the CKT 744 (LT BLU) to the normally closed contacts of the DRL On relay. The DRL On relay will energize and open up its contacts when the ignition switch is in the RUN position and the engine is not running. The ground path is now provided through CKT 729 (RED/BLK), through the DRL series dropping resistor, and through CKT 715 (RED/YEL) to the normally closed contacts of the lighting relay. The low beam filaments now light at 90 percent intensity because of the additional voltage drop across the DRL series dropping resistor.