GM Service Manual Online
For 1990-2009 cars only

Park, Side Marker, and Rear License Lamps

The voltage is supplied through the PRK LP fuse to the headlamp switch at all times. The voltage is supplied to the following lamps with the headlamp switch in PARK or HEAD:

    • The park lamp
    • The side marker lamps
    • The rear license lamp

Stoplamps (Pickup)

The voltage is supplied at all times through the STOP HAZ Fuse 1 to the TCC brake and cruise control release switch. The contacts in the TCC brake and cruise control release switch close when the brake pedal is depressed. The voltage is supplied through the high mounted stoplamp relay to the multifunction switch then to the left and right stoplamps. The stoplamp will flash as a turn signal lamp if the turn signal switch is ON. The stoplamp on the opposite side will serve as a stoplamp.

Stoplamps (Utility)

The voltage is supplied at all times through the STOP HAZ Fuse 1 to the TCC brake and cruise control release switch. The contacts in the TCC brake and cruise control release switch close when the brake pedal is depressed. The voltage is supplied through the hazard switch and the turn signal switch to the left and right stoplamps. The stoplamp will flash as a turn signal lamp if the turn signal switch is on. The stoplamp on the opposite side will serve as a stoplamp.

Turn Signal Lamps

The voltage is supplied through the TURN B/U Fuse and the turn signal lamp flasher with the ignition switch in RUN or START. The voltage is supplied to the normally closed contact of the hazard switch to the turn signal switch.

The voltage is supplied to the left front park and turn signal lamp by the CKT 14 (LT BLU) wire with the turn signal switch in the left turn position. The voltage is supplied to the right front park and the turn signal lamp by the CKT 15 (DK BLU) wire. The voltage is supplied to the left rear park and the turn signal lamps by the CKT 18 (YEL) wire. The voltage is supplied to the right rear park and turn signal lamps by CKT 19 (DK GRN) and CKT 18 (YEL) (Utility Only).

The lamps illuminate immediately. The lamps begin to flash when the current flow heats the timing element in the flasher and repeatedly opens and closes the circuit. Voltage is supplied to the left front park lamp. The turn signal lamp will also be supplied to the left front side marker lamp. The left front side marker lamp will find a path to ground through the splice S133 and the other lamps connected in a parallel ground, if the headlamp switch and the panel dimmer switch are in the OFF position. The lamps provide a low resistance path to the ground. The side marker lamp will flash with the turn signal lamp. The lamps used for the ground path will not flash. The side marker lamp is much higher than that across the other lamps since the voltage will drop across.

The voltage is supplied through the following components to the side marker and the park lamps when the headlamp switch is either in the PARK or the HEAD position:

    • The PARK LPS fuse
    • The headlamp switch
    • Splice S133

The left front marker lamp will have voltage at both connections. The left front marker lamp will go out if the turn/hazard switch is in the turn left position. The marker lamp will be grounded through the turn lamp. The lamp will go on when the flasher removes the voltage from the turn lamp. The left front marker lamp will flash on when the left front park/turn lamp goes off and off when the turn lamp is on.

The voltage will be supplied to the right lamps in the same way with the turn/hazard switch in TURN RIGHT.

Hazard Lamps

The voltage is supplied at all times, through the STOP HAZ Fuse and the hazard lamp flasher to the normally open contact of the hazard switch in the turn/hazard switch. The voltage is supplied to both the front and rear turn lamps with the hazard switch in the HAZARD FLASH position. All of the turn lamps and turn indicators flash on and off.

The front marker lamps flash in the HAZARD FLASH position just as in the TURN RIGHT and TURN LEFT positions. The lamps will flash on when the hazard lamps are on if the headlamp switch is in the OFF position. The lamps flash on when the hazard lamps are off and the hazard lamps are on if the headlamp switch is either in the PARK or the HEAD positions.

In the HAZARD position the circuit is always open and the hazard lamp flasher controls the lamps.

Park and Marker Lamps

The voltage is supplied through the PRK LPS Fuse to the headlamp switch at all times. The voltage is supplied to the following lamps with the headlamp switch in the PARK or the HEAD position:

    • The park lamps
    • The tail lamps
    • The marker lamps
    • The licence lamps