For 1990-2009 cars

### Exterior Lamps

The exterior lighting system consist of the following lamps:

• | The Headlamps

• | The Daytime Running Lamps

• | The Fog Lamps

• | The Park, Tail and Marker Lamps

• | The Turn Signal Lamps

• | The Stop Lamps

• | The Backup Lamps

### Headlamps

The headlamps may be turned on 2 different ways. First, when the driver places the headlamp switch in the HEADLAMP position, for normal operation. Second, with the headlamp switch placed in the OFF position, for automatic lamp control (ALC). During ALC, the headlamps will be in day time running lamp (DRL) operation in daylight conditions, or low beam operation in low light conditions. The LT HDLP and RT HDLP fuses, supply battery positive voltage from the underhood junction block to the left and right headlamps. The circuit continues through both low and high beam lamps, then back to the underhood junction block. The low beam and high beam circuits continue to the headlamp switch. The low beam and high beam circuits also provide the body control module (BCM) with both low and high beam inputs. The headlamp switch includes the dimmer switch and the flash-to-pass switch. When the headlamp switch is placed in the HEADLAMP position a path to ground is provided. Ground is provided at G304. Depending on the position of the high/low beam switch, either the low or high beam circuit will now have power and ground.

The BACKUP/TURN fuse in the underhood junction block, supplies battery positive voltage to the HEADLAMP relay coil circuit. The HEADLAMP relay switch circuit is connected to the low beam circuit at the headlamp switch. When the headlamp switch is placed in the OFF position, the BCM will automatically turn on the low beams in low light conditions. The BCM energizes the HEADLAMP relay, closing the switch contacts and grounding the low beam circuit. Ground is provided at G304. With the headlights in the low beam position, the high beams may be momentarily turned on or flashed with the dimmer switch handle. The flash-to-pass feature is accomplished by pulling the dimmer switch handle toward the driver. The headlights may be switched to high beam with the opposite movement of the dimmer switch lever. When the headlamp dimmer switch handle is pulled toward the driver, the flash-to-pass switch closes grounding the high beam circuit. Ground is provided at G304. Both high beams will remain on until the driver releases the switch handle.

### Daytime Running Lamps (DRL)

The ambient light sensor is a light sensitive transistor that varies its voltage signal to the body control module (BCM) in response to changes to the outside (ambient) light level. When the BCM receives this signal it will either turn on the daytime running lights (DRL) or the headlights. Any function or condition that turns on the headlights will cancel the daytime running lamps operation. With the headlight switch in the OFF position, the headlights will either be turned ON or OFF, after an approximate 30 second delay depending on whether daylight or low light conditions are sensed. The LT HEADLAMP fuse in the underhood junction block supplies ignition positive voltage to the daytime running lamp (DRL) relay coil circuit. The DRL relay switch contacts are connected to the low beam circuit. When the headlamp switch is placed in the OFF position, the BCM will either turn on or off the daytime running lamps, depending on whether daylight or low light conditions are sensed. The BCM energizes the DRL relay, closing the switch contacts and grounding the low beam circuit. Ground is provided at G103. The DRL illuminate the low beam headlights at a reduced intensity. The DRL will operate when the ignition switch is in the ON position, the gear selector is not in the PARK position and the parking brake is released. When these conditions have been met and the ambient light sensor indicates daytime conditions, the DRL will illuminate.

DRL operation in Manual Transmission equipped vehicles will occur when the ignition switch is in the ON position, and the parking brake is released.

### Fog Lamps

The FOG LAMP fuse supplies battery positive voltage to the switch side of the FOG LAMP relay. When the exterior lamps are on, the PARKLAMP relay provides voltage to the coil side of the FOG LAMP relay. When the Fog Lamp switch is placed in the ON position, ground is provided to the coil side of the FOG LAMP relay through G304. This energizes the FOG LAMP relay. The FOG LAMP relay then provides voltage to the individual fog lamps. The fog lamps are grounded at G103.

### Park, Tail and Marker Lamps

The park, tail and marker lamps, including the license lamps, are turned on when the headlamp switch is placed in the PARK or HEADLAMP position, or anytime the headlights are requested. The PARK LAMP fuse in the underhood junction block supplies battery positive voltage to the PARKLAMP relay switch contacts. The PARK LAMP fuse in the underhood junction block also supplies battery positive voltage to the PARKLAMP relay coil. When the park lamps are turned on the body control module (BCM) energizes the PARKLAMP relay. Current flow is from the PARKLAMP relay to their respective park and marker lamps and to ground. Ground is provided at G103, G191, G304, G401, or G464.

### Remote Keyless Entry Exterior Lamp Illumination

On vehicles with a remote control door lock receiver (RCDLR), when the RCDLR module receives a door unlock command from the remote keyless entry (RKE) transmitter, the RCDLR module will send a class 2 message to the BCM indicating that an UNLOCK command has been received. The BCM will then flash the park lamps twice. With all the doors closed, and the RKE transmitter is used to lock the doors, the park lamps will flash twice. The park lamps will not flash if the rear compartment is opened using the RKE transmitter.

On vehicles without a RCDLR when the BCM receives a door unlock command from the RKE transmitter, the BCM will then flash the park lamps twice. With all the doors closed, and the RKE transmitter is used to lock the doors, the park lamps will flash twice. The park lamps will not flash if the rear compartment is opened using the RKE transmitter.

### Turn Signal Lamps

The HAZARD fuse in the Underhood Fuse block supplies battery positive voltage to the flasher module, which is part of the hazard switch assembly. The BACKUP/TURN fuse in the Underhood Fuse block supplies ignition positive voltage to the flasher module. The turn signal lamps may only be activated with the ignition switch in the ON position. When the turn signal switch is placed in either the left or right position, current flow is from the flasher module's output to the turn signal switch assembly. The flasher module then sends an ON-OFF voltage signal to either the left or right turn signals and their instrument panel cluster (IPC) indicator. When the hazard switch is pressed, all the turn signal lamps will flash including both IPC turn signal indicators.

### Stop Lamps

The BRAKE fuse in the Underhood Fuse block supplies battery positive voltage to the normally open stop lamp switch. When the driver presses the brake pedal, the switch contacts close and battery positive voltage is supplied to both left and right stop lamp assemblies and to the center high mounted stop lamp (CHMSL). The stop lamps are grounded at G104, G401 and G464.

### Backup Lamps

Vehicles equipped with an automatic transmission, the BACKUP/TURN fuse in the Underhood Fuse block supplies battery positive voltage to the Transaxle Range switch. Vehicles equipped with a manual transmission, the BACKUP/TURN fuse in the Underhood Fuse block supplies battery positive voltage to the backup lamp switch. When the driver places the gear selector lever in the REVERSE position, the current flow is from the Transaxle Range switch or the backup lamp switch, to the back up lamps. The backup lamps are grounded at G401 and G403.

### Inadvertent Power

The BCM used in this vehicle controls the lighting system through circuits that enable both the exterior lamp functions of park, head, and fog lamps as well as the interior lamps. The BCM opens these enabling circuits shortly after the ignition switch is turned OFF with no lamp switch activity. If the ignition switch is turned to any position other than OFF, or if a lamp switch is activated during this period, the timer will reset itself again.