Exterior Lighting Systems Description and Operation 2

Exterior Lighting Systems Description and Operation

Exterior Lamps

Park, Tail, License and Marker Lamps

The tail, stop, and turn signal functions are performed by the quarter mounted tail lamps. The quarter mounted tail lamp consists of a red lens and incandescent bulbs. The tail lamp assemblies wrap around the corner of the vehicle and serve as the rear side marker. The lower portion of each lamp contains reflectors to alert approaching vehicles for nighttime driving safety. The front park and side marker lamps are part of the front headlamp assembly and use an incandescent bulb. The park, tail, license and marker lamps are turned ON when the headlamp switch is placed in the PARK LAMP or HEADLAMP position or anytime the headlights are requested. The park lamps are also turned ON with the front fog lamps. When the ignition switch is in the ON position, the DIM provides battery positive voltage to the controlled positive voltage circuit of the park lamp relay coil. The fuse block underhood supplies battery positive voltage to the switch contacts of the park lamp relay. When the headlamp switch is in the PARK LAMP or the HEADLAMP position, the park lamp switch on signal circuit has ground at G200. In response to this signal, the DIM provides ground to the control circuit of the park lamp relay coil, which energizes the relay coil. This closes the relay switch contacts. Current flows from the park lamp relay to the LIC/Dimming fuse, LT PARK fuse and to the RT PARK fuse. From the fuse, the current flows to the park lamps. The front park lamps are grounded at G104 and the tail lamps are grounded at G401 and G402. The dimming fuse supplies battery positive voltage to the license lamps, underhood lamp and to the dash integration module (DIM) park lamp input, for interior lamps dimming. The license lamps are grounded at G402. The inadvertent power control feature prevents the park lights from remaining on more than 10 minutes if left ON. If the park lights are turned ON after the ignition switch has been turned OFF, or is in the ACCY position, they will remain ON until turned OFF or the battery runs dead.

Position Lamps

The position lamps are on export vehicles only. European countries require that side position lamps are activated when the vehicle is parked along the side of the road. This feature utilizes the front and rear park and the side marker lamps. The position lamp function operates only when the key is in the OFF position and the gear selector is in the PARK position on vehicles equipped with automatic transmissions or when the parking brake is applied on vehicles equipped with manual transmissions. The position lamp function will operate when the turn signal switch is placed in the right turn position for the right side position lamps to illuminate or the left turn position for the left side position lamps to illuminate. Battery positive voltage is supplied to the standing lamp relay coil and switch. Battery positive voltage is supplied through the normally closed relay contacts of the standing lamp relay switch to each position lamp relay coil. Battery positive voltage is supplied to each position lamp relay switch. When the driver places the turn signal lever in the right or left turn position the turn signal switch grounds the respective position lamp relay control circuit. This energizes the relay coil, closing the switch contacts providing battery voltage to the respective park and side marker lamps. When the gear selector is out of the PARK position on vehicles with automatics transmissions or the parking brake is released on vehicles with manual transmissions, the rear integration module (RIM) grounds the standing lamp relay coil which removes battery positive voltage from each position lamp relay coil.

Stop Lamps

The brake pedal position sensor is a resistive device used to sense the action of the driver's application of the brake pedal. The brake pedal position sensor provides an analog signal that will increase as the brake pedal is pressed.

The brake pedal position sensor receives both a 5-volt reference voltage and a low reference signal from the electronic brake control module (EBCM). When the brake pedal is pressed, a variable signal is applied from the brake pedal position sensor to the EBCM through the brake sensor signal circuit. The fuse block left rear supplies battery positive voltage to the bass relay switch through the BASS fuse. One side of the bass relay coil is permanently grounded at G402. The EBCM supplies voltage to the bass relay coil upon receiving the signal from the brake pedal position sensor. The switch contacts of the bass relay close and battery positive voltage is applied through the bass relay switch to the center high mounted stop lamp (CHMSL), and to the turn signal/hazard flasher module through the stop lamp switch signal circuit. The ground for the CHMSL is applied from G402. The turn signal/hazard flasher module then supplies voltage to the left and right stop lamps in the tail lamp assemblies that have ground at G401 and G402. For export vehicles the stop lamps receive battery positive voltage directly from the bass relay.

Turn Signal/Hazard Flasher Lamps

The TSIG/HAZ fuse in the rear fuse block supplies battery positive voltage to the flasher module. The module is part of the hazard switch assembly. The flasher module has ground at G201. The turn signal lamps may only be activated with the ignition switch in the ON or START position. The IGN-1 fuse in the rear fuse block supplies battery positive voltage to the turn signal switch. When the turn signal switch is placed in either the left or right position, current flows from the turn signal switch assembly to the flasher module. The flasher module then sends an on-off voltage signal to either the left or right turn signals and the appropriate IPC indicator. When the IPC receives an input from either of the turn signals it starts to track vehicle mileage. When the IPC has determine that the vehicle has traveled over 1.6 km (1 mi) with 1 of the turn signals continuously engaged, it shall display the DIC message Turn Signal On and request the appropriate chime to notify the driver. The left turn signals have ground at G401 and at G402. The right turn signals have ground at G401.

The hazard flashers may be activated in any power mode. The hazard flasher switch is permanently grounded through G200. When the driver turns ON the hazard flasher switch the contacts in the switch close, grounding the hazard switch input circuit of the turn signal/hazard flasher module. The turn signal/hazard flasher module then supplies battery voltage to all four turn signal lamps and IPC in an ON and OFF duty cycle. This illuminates the turn signal lamps in the same manner as explained above. When a THEFT is occurring, the DIM provides a ground to the turn signal/hazard flasher module hazard input. This allows the hazard lamps to flash during theft detection.

Repeater Lamps

The repeater lamps are on export vehicles only. Each lamp is located in the front fender. The repeater lamps are used as additional turn signal lamps, and operate as described in the Turn Signal/Hazard Flasher Lamps description. The repeater lamps have ground at G104.

Backup Lamps

The rear fuse block supplies battery positive voltage through the REVERSE LAMP fuse to the coil and switch terminals of the reverse lamp relay. The DIM sends a power mode message to the RIM indicating that the ignition is in the ON position. When the driver of an automatic transmission equipped vehicle places the gear selector in the REVERSE position, the powertrain control module (PCM) sends a class 2 message to the RIM. The message indicates that the gear selector lever is in the REVERSE position. When the driver places a manual transmission equipped vehicle in reverse the reverse gear position switch mounted on the transmission closes. This provides a ground for the reverse gear position switch signal line, informing the RIM that the transmission is in reverse. For both automatic and manual transmission vehicles the RIM then grounds the control circuit of the reverse lamp relay. This energizes the reverse lamp relay, closing the switch side contacts and providing battery positive voltage to the backup lamp bulbs. The backup lamps are permanently grounded at G402. With both power and ground the backup lamp bulbs illuminate. Once the driver moves the shift lever out of the reverse position a message is send either by class 2 by the PCM or the reverse gear position switch opens causing the RIM to remove the ground from the reverse lamp relay control circuit. This opens the contacts in the relay turning OFF the backup lamps.

Remote Keyless Entry Exterior Lamp Illumination

When the remote control door lock receiver (RCDLR) detects a door UNLOCK command from the keyless entry transmitter, the RCDLR will send a class 2 message to the dash integration module (DIM). The DIM must have inputs that indicate that the ignition switch is OFF, the park lamps are OFF, all the doors are closed, and the Photocell status is Dark conditions. The DIM will then activate the flash to pass relay, park lamp relay and send a class 2 message to the rear integration module (RIM) requesting reverse lamp illumination. The reverse lamp feature may not be available in all countries due to possible export regulations. The DIM will flash the headlamps and park lamps twice, then keep the park and reverse lamps on approximately 20 seconds or until a door is opened. When the RCDLR detects a door LOCK command from the keyless entry transmitter, The DIM will flash the headlights and park lights once. In daylight conditions, the DIM will activate the park lamp relay only to flash the park lamps twice with a door UNLOCK command and once with a door LOCK command from the keyless entry transmitter.

Battery Run Down Protection/Inadvertent Power

To provide battery run down protection, the exterior lamps will be deactivated automatically under certain conditions. The DIM monitors the state of the headlamp switch. If the park or headlamp switch is ON when the ignition switch is placed in either the CRANK or RUN position and then placed in the OFF position, the DIM initiates a 10 minute timer. At the end of the 10 minutes, the DIM will turn OFF the control power output to the park and headlamp relay coils, deactivating the exterior lamps. This feature will be cancelled if any power mode other than OFF becomes active. The DIM will disable battery run down protection if any of the following conditions exist. The park or headlamp switch is placed in the ON to OFF position, and back to the ON position during battery run down protection. The DIM determined that the park or headlamp switch was not active when the ignition was turned OFF.