GM Service Manual Online
For 1990-2009 cars only

Exterior Lights Circuit Description Domestic

Park/Side Marker and Tail Lamps

The park/side marker and tail lamps are split between the following 3 fuses:

    • TURN-B/U Fuse 20A
    • STOP/HAZ Fuse 20A
    • PK LPS Fuse 20A

When the headlamp and panel dimmer switch is in the auto position, the body control module (BCM) controls the park lamp relay by grounding CKT 1080 (WHT) based on the input of the ambient light sensor. The PK LPS fuse supplies battery positive voltage (B+) to the relay at all times.

Stop Lamps

The STOP/HAZ fuse supplies battery positive voltage (B+) at all times to the brake pedal position (BPPS) switch. When the brake pedal is depressed, CKT 17 (WHT) supplies battery positive voltage (B+) to the CHMSL lighting assembly causing the lamps to light and ground through CKT 1350 (BLK). Power is also connected to the rear lamps through CKT 17 (WHT) via S200.

Turn Signal lamps

Voltage applies from the turn-B/U fuse to the normally closed pole of the hazard switch in the turn/hazard switch when the ignition switch is in the RUN or the START position. With the turn/hazard switch in the LEFT TURN position, voltage applies from the switch to CKT 14 (LT BLU) and to CKT 18 (YEL). When the voltage applies, the following lamps flash ON and OFF as the turn/hazard flasher module controls the current flow:

    • The left side front turn
    • The rear turn
    • The indicator

The current flow continuously opens and closes the following right side turn lamp circuits:

    • CKT 15 (DK BLU)
    • CKT 19 (DK GRN)

With the park lamps ON and the turn lamps ON, voltage applies to both of the terminals of the front side marker lamp. When this occurs, the front turn lamp is OFF. When the front turn lamp is OFF, voltage applies to only one terminal of the marker lamp. When this occurs, the marker lamp will flash ON. The turn lamp and the marker lamp continue to flash ON and OFF in sequence until the turn switch is in the OFF position.

Hazard Lamps

When the turn/hazard switch is in the hazard position, voltage is supplied from the STOP/HAZ fuse at all times through the turn/hazard switch to the turn/hazard flasher via CKT 140 (ORN) and CKT 1508 (LT BLU). The flasher then passes current back to the turn/hazard switch in an intermittent on off pattern through CKT 16 (PPL). From the turn/hazard switch, voltage is supplied to the LT TURN and the RT TURN lamps through CKT 14 (LT BLU) or CKT 15 (DK BLU).

Trailer Wiring

Below is a list of blunt cut wires for the trailer harness option UY7

Individual Wire Functions

CKT ID Number

Color

Description

22

WHT

Trailer Ground

19

DK GRN

RH Turn Signal

9

BRN

Park Lamp

18

YEL

LH Turn Signal

17

WHT

CHMSL (Stop Lamp Feed)

24

LT GRN

Back Up Lamp Feed

940

ORN

Heavy Duty Battery Feed

47

DK BLU

Heavy Duty Auxiliary Feed

Exterior Lights Circuit Description VE1

Park/Side Marker and Tail Lamps

The park/side marker and tail lamps are split between the following 3 fuses:

    • TURN-B/U Fuse 20A
    • STOP/HAZ Fuse 20A
    • PK LPS Fuse 20A

When the headlamp and panel dimmer switch is turned to the PARK position, the body control module (BCM) ground the PARK LAMP relay. The relay supplies power to the ( CKT through the relay. The PK LPS fuse supplies battery positive voltage (B+) to the relay at all times.

Stop Lamps

The STOP/HAZ fuse supplies battery positive voltage (B+) at all times to the brake pedal position (BPPS) switch. When the brake pedal is depressed, CKT 17 (WHT) supplies battery positive voltage (B+) to the CHMSL lighting assembly causing the lamps to light and ground through CKT 1350 (BLK).

Turn Signal lamps

When the ignition switch is in the run position and the turn/hazard switch is in a turn position, voltage is supplied from the TURN--B/U fuse through the turn/hazard switch to the turn/hazard flasher through CKT 14 (LT BLU) and to CKT 18 (YEL).. The VE1 option contains turn signal lamps on side the side of the vehicle, in addition to the lamps on the four corners of the vehicle. Refer to Exterior Lights Schematics for circuit diagram.

Hazard Lamps

When the turn/hazard switch is in the hazard position, voltage is supplied from the STOP/HAZ fuse at all times through the turn/hazard switch to the turn/hazard flasher via CKT 140 (ORN). The flasher then passes current back to the turn/hazard switch in an intermittent on off pattern through CKT 16 (PPL). From the turn/hazard switch, voltage is supplied to the LT TURN and the RT TURN lamps through CKT 14 (LT BLU) or CKT 15 (DK BLU).

Trailer Wiring

Below is a list of blunt cut wires for the trailer harness option UY7

Individual Wire Functions

CKT ID Number

Color

Description

22

WHT

Trailer Ground

19

DK GRN

RH Turn Signal

9

BRN

Park Lamp

18

YEL

LH Turn Signal

17

WHT

CHMSL (Stop Lamp Feed)

24

LT GRN

Back Up Lamp Feed

940

ORN

Heavy Duty Battery Feed

47

DK BLU

Heavy Duty Auxiliary Feed