GM Service Manual Online
For 1990-2009 cars only

Park, Marker, Tail And License Lamps

Voltage is applied continuously to the tail relay pins 4 and 2. The coil is energized when the daytime running lamps control module is active in normal park or headlamp operation.

When the coils are energized current flows through the tail fuse and then into the following lamps:

    • The park lamps
    • The rear taillamp
    • The IP illumination
    • The license plate lamps

Turn Lamps

Voltage is applied from the turn fuse to cavity 7 of the hazard switch. Current flows through the switch to cavity 5 where it continues to cavity 2 of the turn/hazard flasher. Cavity 2 applies voltage to the timing coil. At the same time cavity 2 applies voltage to the contact that closes according to the timing of the turn/hazard flasher. When the contacts are closed it applies current to the turn signal/headlamp switch cavity 2. If no direction is set by the turn signal switch an open occurs between cavities 1,2 and 3 of the switch. Current flows only to the left or right set of lamps, depending which way the turn signal switch is turned to.

The following lamps are turned on pertaining to the side the switch is activated to:

    • The left or right front turnlamp
    • The left or right rear turnlamp
    • The left or right indicator lamp

Hazard Lamps

Voltage is applied from Hazard fuse to cavity 6 of the hazard switch. When turned to the on position current flows through the switch to cavity 5 where it continues to cavity 2 of the turn/hazard flasher. Cavity 2 applies voltage to the timing coil. At the same time cavity 2 applies voltage to the contact that closes according to the timing of the turn/hazard flasher. When the contacts are closed it applies current to the hazard switch cavity 4. Current flows from cavity 4 through the closed contacts at cavity 1 and 2.

The following lamps are turned on when cavities 1 and 2 are charged:

    • The left and right front turnlamp
    • The left and right rear turnlamp
    • The left and right indicator lamp

Stoplamps and Center High Mount Stoplamp

Voltage is applied continuously from the stop fuse to the stoplamp switch. Voltage is applied from the stoplamp switch to junction block 1 C6 cavity 6 when the brake pedal is pressed. Voltage flows to junction block 1 C5 cavity 7, continuing to SP450. At the same time that happens current flows through junction block 1 C3 cavity 1 to junction block 3 C3 cavity 2.

SP450 applies voltage to the following lamps:

    • The left and right stoplamps
    • The center high mounted stoplamp (CHMSL)

Junction block 3 C3 cavity 2 applies voltage to the following brake signal receivers:

    • Shift Lock Control Module (w/ automatic transaxle)
    • Brake Pressure Modulator Valve (w/ ABS)
    • Powertrain Control Module