Voltage for connector C8, the blackout (B/O) marker lamps, is supplied through the accessory voltage circuit YL (243) located in the I/P relay center. From there the OG (40) wire supplies voltage to the blackout (B/O) service switch. When the blackout (B/O) service switch is placed in blackout (B/O) mode, voltage is applied to the PK (911) wire to inline 5A fuse. Voltage is then applied to the BN/WH (900) wire for front blackout (B/O) marker lamps and BN/WH (900) wire for rear blackout (B/O) marker lamps. Ground for the front blackout (B/O) marker lamps is supplied through G100M for the front and G903M and G902M for the rear.

The blackout (B/O) stoplamps voltage is supplied through the stop LP fuse OG (1540) wire to the TCC/stoplamp switch at all times. When the brake pedal is depressed, the stoplamp switch is closed and powers the WH (17) wire to the blackout (B/O) service switch. When in blackout (B/O) mode, voltage is applied from the DK GN/WH (902) wire to the blackout (B/O) stoplamps. The blackout (B/O) stoplamps receive constant ground through G903M and G902M.

This section focuses on the function and service of the blackout (B/O) headlamp, the front and rear blackout (B/O) marker lamps, and the service/blackout (B/O) lamp switch. All other lamps are covered in the 2005 C/K Truck Owner Manual. As military options the blackout (B/O) lamps provide a stealthy, low illumination alternative to standard lighting systems, also available on these vehicles. The blackout (B/O) headlamp is identical on these vehicles. The front blackout (B/O) marker lamps are mounted in the bumper of this vehicle. The rear blackout (B/O) marker lamps are arranged in the same relative position on the rear bumpers.

The service/blackout (B/O) lamp switches, mounted at the lower center dash, control blackout (B/O) lamp and standard lamp functions. A pair of toggles operates these switches. The blackout (B/O) drive toggle is mounted on the right. When the service light toggle is moved up to the ON position it activates all service lights and enables all normal service light functions elsewhere to be turned ON if needed. When moved to the ALL OFF position this toggle shuts off all lamps and auxiliary lamps. When the switch is moved to blackout (B/O) ON only the blackout (B/O) lighting will work, which includes the blackout (B/O) markers, front and rear, and the blackout (B/O) headlamp. Within the rear marker lamps are separate color markers. Yellow will illuminate for the brakes and red will illuminate for drive mode. The front markers illuminate in yellow. (The horn is inoperative while the blackout (B/O) toggle is in the ON position.) All warning lamps in the I/P remain functional regardless of the toggle position. If the vehicle is parked for over 24 hours, place the service switch in the ALL OFF position.

To operate the blackout (B/O)/drive light switch pull it out and up to the ON position; this will activate the front blackout (B/O) headlamp. This will occur provided the service light/blackout (B/O) switch remains in the ON or down position. Pulling the left blackout (B/O) drive light switch out and down to the OFF position will turn it OFF. Releasing the switch from ON or OFF will cause it to return to the center position automatically.

The following Exterior/Interior lights function tables are for the service light/blackout (B/O) control switch and clarify under what conditions various exterior and interior lighting functions activate. Additional details are found in the 2005 C/K Truck Owner Manual.

When the ignition switch is ON, voltage is supplied from the blackout (B/O) switch to the interior toggle switch on circuit 912 (OG). The voltage leaves the switch on circuit 800 (BR) or 803 (BN/WH) depending on the switches’ position. The voltage on these circuits goes to the rear toggle switch then to the topper dome lamp. The lamp is ground on the CHMSL circuit.

The topper dome lamp is controlled by two 3-way switches and a lamp mounted switch. The interior switch is mounted in the accessory panel and the other is mounted on the left rear of the pickup bed. The switch mounted on the lamp must be in the ON position for the two 3-way switches to operate the lamp.

When the headlamp switch is in the ON position voltage is applied through the BN 9 wire and is grounded through the BK 150 wire.

The voltmeter lamp provides illumination to the voltmeter mounted in the accessory instrument panel.