GM Service Manual Online
For 1990-2009 cars only

Headlamp Switch

When the headlamp switch is placed in the PARK or ON position, the dash integration module (DIM) Park Lamp Switch input is grounded via CKT 301 (BRN/WHT).

Park Lamps

The dash integration module (DIM) supplies battery positive voltage (B+) to the PRK LP relay coil via CKT 1483 (DK GRN) when the headlamps or park lamps need to be on or when the ignition switch is in the ON position. Battery positive voltage (B+) is supplied at all times to the PRK LP relay switch. When the park lamps are to be active, the DIM grounds the PRK LP relay coil via CKT 1080 (WHT). The coil is energized, closing the switch contacts. Battery positive voltage (B+) is supplied to the rear fuse block LP PK R Fuse, LP PK L Fuse, and DIMR Fuse. The LP PK R Fuse supplies battery positive voltage (B+) to the LH park lamps via CKT 309 (BRN/WHT). The LP PK L Fuse supplies battery positive voltage (B+) to the LH park lamps via CKT 709 (PPL). The LH and RH park lamps are permanently grounded through CKT 850 (BLK) to G402 or CKT 1050 (BLK) to G401, so all park lamps have power and ground, and then light. The DIMR Fuse supplies battery positive voltage (B+) to the DIM Park Lamp input for interior lamps dimming, the license lamps, the underhood lamp, and the cornering lamps via CKT 32 (YEL). The license lamps are permanently grounded through CKT 850 (BLK) to G402, so both license lamps have power and ground, and then light.

Perimeter Lighting

Perimeter lighting will activate the vehicle's park lamps, backup lamps, and high beam headlamps for 20 seconds or until a door is opened after a driver's door unlock command using the keyless entry transmitter. Refer to Headlights Circuit Description . Refer to Backup Lamp Circuit Description .

Turn Lamps

Battery positive voltage (B+) is supplied at all times to the turn signal/hazard flasher module in the hazard switch assembly from the rear fuse block TSIG/HAZ Fuse via CKT 1740 (ORN). The turn signal/hazard flasher module is permanently ground to G201 via CKT 450 (BLK). Battery positive voltage (B+) is supplied with the ignition switch in the ON or START position to the turn signal switch in the steering column from the rear fuse block IGN 1 Fuse via CKT 1039 (PNK).

When the turn signal switch is placed in the position to indicate a LH turn, battery positive voltage (B+) is input to the turn signal/hazard flasher module Left Turn Input via CKT 1428 (DK GRN). In response to this input, the turn signal/hazard flasher module supplies battery positive voltage (B+) in an on and off flashing pattern via CKT 14 (LT BLU) to the LH turn lamps and the instrument cluster (IPC) LH Turn Input. The LH turn lamps are permanently grounded through CKT 250 to G104 and CKT 850 (BLK) to G402, so the LH turn lamps light when they have power and ground and turn off while power is removed. The instrument cluster (IPC) will also light the LH turn indicator.

When the turn signal switch is placed in the position to indicate a RH turn, battery positive voltage (B+) is input to the turn signal/hazard flasher module Right Turn Input via CKT 1427 (LT GRN). In response to this input, the turn signal/hazard flasher module supplies battery positive voltage (B+) in an on and off flashing pattern via CKT 15 (DK BLU) to the RH turn lamps and the instrument cluster (IPC) RH Turn Input. The RH turn lamps are permanently grounded through CKT 250 to G104 and CKT 850 (BLK) to G402, so the RH turn lamps light when they have power and ground and turn off while power is removed. The instrument cluster (IPC) will also light the RH turn indicator.

Hazard Lamps

When the hazard switch is pressed, the switch contacts close and the turn signal/hazard flasher module Hazard Input is grounded via CKT 450 (BLK) to G201. In response to this input, the turn signal/hazard flasher module supplies battery positive voltage (B+) in an on and off flashing pattern through CKT 14 (LT BLU) and CKT 15 (DK BLU) to all turn lamps. All turn lamps and both turn indicators then light as described above.

When a THEFT is occurring, the dash integration module (DIM) will ground the turn signal/hazard flasher module Hazard Input via CKT 111 (WHT). Refer to Content Theft Deterrent (CTD) Circuit Description in Theft Deterrent.

Stop Lamps

Battery positive voltage (B+) is supplied at all times to the stoplamp/BTSI switch from the rear fuse block STOP LP Fuse via CKT 1640 (ORN). When the brake pedal is pressed, the stoplamp/BTSI switch contacts close and battery positive voltage (B+) is supplies via CKT 17 (WHT) to the center high mounted stop lamp (CHMSL) and the tail/stop lamps. The center high mounted stop lamp (CHMSL) and LH tail/stop lamp are permanently grounded via CKT 850 (BLK) to G402. The RH tail/stop lamp is permanently grounded through CKT 1050 (BLK) to G401. The stop lamps light when they receive both power and ground.

Cornering Lamps

When the park lamps are on, battery positive voltage (B+) is supplied to the turn signal switch via CKT 32 (YEL). When the turn signal switch is placed in the position to indicate a LH turn, battery positive voltage (B+) is supplied to the LH cornering lamp via CKT 57 (ORN). When the turn signal switch is placed in the position to indicate a RH turn, battery positive voltage (B+) is supplied to the RH cornering lamp via CKT 58 (BLK). Both cornering lamps are permanently grounded via CKT 1050 (BLK) to G401. The cornering lamps light when they receive both power and ground.

Underhood Lamp

When the park lamps are on, battery positive voltage (B+) is supplied to the underhood lamp via CKT 32 (YEL). The underhood lamp is permanently grounded through CKT 150 to G101. When the hood is opened, the switch in the underhood lamp closes and supplies ground to the bulb in the underhood lamp. The underhood lamp lights when it receives both power and ground.

Position Lamps (Export)

Battery positive voltage (B+) is supplied at all times to the STANDING LP relay coil and switch in the rear compartment relay center via CKT 3140 (ORN) from the rear fuse block EXPORT LGT Fuse. Battery positive voltage (B+) is supplied through the normally closed relay contacts of the STANDING LP relay to the POSN LP R relay coil and the POSN LP L relay coil in the rear compartment relay center via CKT 1430 (WHT). When the gear selector is in the PARK position, the dash integration module (DIM) grounds the STANDING LP relay coil via CKT 1429 (BRN) removing battery positive voltage (B+) from the POSN LP R relay and POSN LP L relay. The position lamps light only with the ignition switch in the OFF position.

Battery positive voltage (B+) is supplied at all times to the POSN LP R relay normally open switch via CKT 3140 (ORN) from the rear fuse block EXPORT LGT Fuse. When the headlamp switch is placed in the RH PARK position, the POSN LP R relay coil is grounded via CKT 1432 (DK BLU) through the headlamp switch RH PARK switch contact and CKT 351 (BLK/WHT). The coil is energized, closing the switch contacts from the normally open position. Battery positive voltage (B+) then is supplied to the RH position lamp and the RH tail/stop lamp via CKT 1473 (BRN/WHT). The position lamp and tail/stop lamp are permanently grounded via CKT 1050 (BLK) to G401, so the RH position lamp has power and ground, and then lights. When the POSN LP R relay is in its normally closed position, battery positive voltage (B+) is supplied via CKT 309 (BRN/WHT) through the relay to the RH position lamp and the RH tail/stop lamp via CKT 1473 (BRN/WHT).

Battery positive voltage (B+) is supplied at all times to the POSN LP L relay normally open switch via CKT 3140 (ORN) from the rear fuse block EXPORT LGT Fuse. When the headlamp switch is placed in the LH PARK position, the POSN LP L relay coil is grounded via CKT 1431 (LT GRN) through the headlamp switch LH PARK switch contact and CKT 351 (BLK/WHT). The coil is energized, closing the switch contacts from the normally open position. Battery positive voltage (B+) then is supplied to the LH position lamp and the LH tail/stop lamp via CKT 1472 (PPL). The position lamp and tail/stop lamp are permanently grounded via CKT 1050 (BLK) to G401, so the RH position lamp has power and ground, and then lights. When the POSN LP L relay switch is in its normally closed position, battery positive voltage (B+) is supplied via CKT 709 (PPL) through the relay to the LH position lamp and the LH tail/stop lamp via CKT 1472 (PPL).