Exterior Lighting Systems 1 of 2

EXTERIOR LIGHTING SYSTEMS DESCRIPTION AND OPERATION

EXTERIOR LAMPS
Exterior lighting consists of the following lamps:
- Headlamps
- Daytime running lamps (DRL)
- Front fog lamps
- Rear fog lamps
- Park, tail, licence and marker lamps
- Turn signal/hazard lamps and repeater lamps
- Stop lamps
- Backup lamps
- Position lamps

HEADLAMPS
The headlamps consist of 2 interchangeable single filament bulbs or 2 high intensity discharge (HID) arc tubes and ballast on each side of the vehicle which provide high and low beams. The lower bulb in the headlamp is the high beam and the upper bulb is the low beam.

The headlamps may be turned on in three different ways:
- When the headlamp switch is placed in the ON position, for normal operation
- When the headlamp switch is placed in the AUTO position, for automatic lamp control (ALC)
- When the headlamp switch is placed in the AUTO position, with the windshield wipers ON in daylight conditions, after a 6 second delay

With the headlamp switch in the ON position, the headlamp switch headlamp on signal circuit is grounded through the headlamp switch to G200. In response to this input, the dash integration module (DIM) provides ground to either the headlamp low beam relay control circuit or the headlamp high beam relay control circuit. The position of the dimmer switch determines which relay coil has ground. The DIM supplies battery positive voltage to the relay coil circuits via the headlamp relay control circuit, if the headlamps are necessary. The fuse block underhood supplies battery positive voltage to both relay switch circuits. When the low beam relay coil is energized, current flows through the LT LOW BEAM fuse and the RT LOW BEAM fuse to the low beam headlamps. The low beam headlamps have ground at G104. When the high beam relay coil is energized, current flows through the LT HI BEAM fuse and the RT HI BEAM fuse to the high beam headlamps. The high beam headlamps also have ground at G104. When the headlamp dimmer switch lever is pulled toward the driver, the flash to pass (FTP) switch closes. This grounds the DIM flash to pass switch signal circuit. In response to this input, the DIM energizes the high beam relay. Both high beams remain on until the driver releases the switch handle. If the low beam headlamps were on during FTP operation, the low beams remain on. The headlights may be switched to high beam with the opposite movement of the dimmer switch lever. All SRXs exported to Norway, Sweden, Finland, or Israel will operate so that the low beam headlamps will also remain illuminated when the dimmer switch is in the high beam position. With the dimmer switch in the high beam position the DIM sends a class 2 message to the instrument panel cluster (IPC) requesting the IPC to illuminate the high beam indicator. If the headlamp switch is left in the ON position, the inadvertent power control feature will turn off the headlights 10 minutes after the ignition switch is turned to the OFF position. If the driver places the headlight switch in the ON position after the ignition switch has been turned OFF, or if the ignition switch is in the ACCY position, the headlights will remain on until turned off or the battery runs dead.

During automatic lamp control (ALC) the headlamps will be in low beam operation during low light conditions. A HEADLAMPS SUGGESTED message will appear on the driver information center DIC when the headlamps and park lamps are off due to all exterior lighting controls being inactive when Dark conditions are sensed. The auto position of the headlamp switch is supplied ground at G200 and enables the auto lamp feature. When the ignition is on the DIM will automatically turn the headlamps on or off according to the Light/Dark photocell Status.

The headlamps on with wipers feature operates when the following conditions are true:
- Ignition is in the RUN position
- Headlamps are currently OFF
- Headlamp switch is in the AUTO position
- Photocell Status indicates Light conditions

When the headlamps on with wipers feature is active the DIC will display the HEADLAMPS SUGGESTED message.

HEADLAMPS - HIGH INTENSITY DISCHARGE (HID)
The High Intensity Discharge (HID) System is made up of the ballast and arc tube. The headlamp ballast receives the headlamp low beam supply voltage, which would normally be used to directly supply the low beam headlamp. Each ballast has a separate ground. The HID headlamp operation consist of three states. The start-up or strike state, run up state, and steady state. When the headlamp switch is turn to the ON position the ballast may draw up to 20 amps to begin the strike state. The ballast will provide multiple high voltage pulses to the arc tube in order to start the bulb. The voltage provided by the ballast during the start-up state ranges from -600 volts to +600 volts. Once an arc is established, the ballast will provide a higher then steady state voltage to the arc tube in order to keep the bulb illuminated. This is called the run up state, on a cold bulb this state could last as long as 41 seconds. On a hot bulb the run up state may last as long as 15 seconds. Steady state operation begins when the bulb reaches the 35 watt power level. The ballast provides the bulb with a minimum of 55 volts during steady state operation.

For proper operation of the HID system ensure the battery and the harness are capable of supplying up to 20 amps of current per ballast, with less than 2 volts of system loss or voltage drop. Each ballast requires up to 20 amps in order to ensure normal start-up and run up of the lamp.

The range of white light that is acceptable is broad when compared to halogens. Therefore, some variation in headlight coloring between the right and left headlamp will be normal. Replace the arc tube only if the arc tube is determined to be at the bulb failure stage.

HID HEADLAMPS LOW VOLTAGE OPERATION
The dash integration module (DIM) monitors the vehicles system voltage while in the RUN power mode. When the system voltage drops below 8.9 volts, the following will occur:

STAGE 1: If the low beam headlamps are on, whether manually or automatically the DIM will turn ON the high beam headlamps by activating the Flash To Pass output control and turn OFF the low beam headlamps

When the system voltage drops below 8.5 volts, the following will occur:
- STAGE 2: If the low beam headlamps are currently on, whether manually or automatically the DIM will turn OFF the low beam headlamps by deactivating the headlamp low beam relay.
- If the headlamps are turned on manually, the manual switch redundancy will cause the low beam headlamps to remain ON.
- If the headlamp dimmer switch is in the high beam position, the low beam headlamps will remain on. The DIM will activate the flash to pass output control.

If during the same ignition cycle, the DIM enters either STAGE 1 or STAGE 2 operations noted above, then determines that the system voltage has risen, the following will occur:
- If the DIM has entered STAGE 2 operation, it will not return to STAGE 1 operation until the system voltage rises above 9.4 volts.
- If the DIM has entered STAGE 1 operation, it will not return to normal operation until the system voltage rises above 9.8 volts.

AUTOMATIC HEADLAMP LEVELING - EXPORT ONLY
The Automatic Headlamp Leveling Systems consist of the following components:
- Ballast module - left
- Ballast module - right
- Headlamp leveling actuator - left
- Headlamp leveling actuator - right
- Headlamp leveling controller - left
- Headlamp leveling controller - right
- Headlamp leveling sensor - front
- Headlamp leveling sensor - rear

The automatic headlamp leveling system automatically maintains the vertical alignment of the headlamps when the vehicle load and driving conditions change. The right and left headlamp leveling controllers share the inputs from the front and rear headlamp leveling sensors to determine vehicle pitch. The headlamp leveling sensors send an output to the headlamp leveling controllers as the vehicle suspension compresses and rebounds. The controllers calculate the difference in vehicle pitch and send a command to the high intensity discharge (HID) ballast. The ballast then drive the headlamp leveling actuators to the position commanded by the controllers. The headlamp leveling system also monitors the performance of the HID bulb and ballast. When the headlamp switch is placed in the ON position the headlamps will go down, and then back up to the center position.

DAYTIME RUNNING LAMPS (DRL) - DOMESTIC/CANADIAN
The daytime running lamps (DRL) will illuminate the right and left front turn signal bulbs continuously. The DRLs will operate when the following conditions are met:
1. Ignition is in the RUN or CRANK position
2. Shift lever is out of the PARK position for vehicles equipped with automatic transmissions or the parking brake is released for vehicles with manual transmissions.
3. High and low beam headlamps are OFF.

When conditions for DRL operation exist, the powertrain control module (PCM) sends a class 2 message to the dash integration module (DIM), indicating the transmission is out of the PARK position. The DIM sends a signal to the turn signal/hazard flasher module by grounding the DRL signal circuit of the turn signal/hazard flasher module. When the turn signal/hazard flasher module receives this signal the module supplies continuous battery voltage to the right and left front turn signal lamps. The turn signal lamps are permanently ground at G104 and therefore illuminate. Turn signal and hazard flasher operation take precedence over DRL operation. For Domestic vehicle only, DRL operation will be disabled if the Photocell Status indicates Dark conditions, the twilight switch status OFF and either the front fog lamps or park lamps are turned ON.

DAYTIME RUNNING LAMPS (DRL) - NORWAY/SWEDEN
The daytime running lamps (DRL) will illuminate the low beam headlamps and the park lamps at normal intensity. The DRLs will operate when the following conditions are met:
- Ignition is in the RUN or CRANK position.
- Shift lever is out of the PARK position for vehicles equipped with automatic transmissions or the parking brake is released for vehicles with manual transmissions.
- High and low beam headlamps are OFF.
- Park lamps are OFF.
- Fog lamps are OFF.

When conditions for DRL operation exist, the powertrain control module (PCM) sends a class 2 message to the dash integration module (DIM), indicating the transmission is out of the PARK position. The DIM will then ground the control circuit of the DRL relay and the park lamp relay. Battery voltage is supplied to the coil and switch side feed circuits of the DRL relay. When the DIM grounds the control circuit of the DRL relay the switch contacts close and battery voltage is supplied to the low beam headlamps. Operation of the park lamps and are the same as described in the park lamp section.

TWILIGHT SENTINEL
Twilight sentinel is a driver convenience that controls the exterior lamps in response to changes to the outside, ambient light level. The twilight sentinel will also keep the exterior lamps on for a pre-selected period of time after the ignition is turned to the OFF position with nighttime conditions sensed. The exterior lamps will be turned off automatically after the delay period elapses. The twilight delay is programmable through the drivers information center (DIC) for Driver 1 and Driver 2. Refer to Personalization Description and Operation in Personalization for more Driver 1 and Driver 2 information. The following delay settings are available to Driver 1 and Driver 2 :
- 0 seconds
- 15 seconds
- 30 seconds
- 60 seconds
- 90 seconds
- 120 seconds
- 180 seconds
- 240 seconds

The DIC will enable the park/headlamp delay feature under the following conditions:
- Time delay is programed to 15 seconds or more for the current driver
- Headlamp switch is in the auto position
- Photocell status is Dark
- Ignition is OFF
- A door has been opened

The delay timer starts once a door is opened. The lights will not turn off until the set time has been completed.

FRONT FOG LAMPS
With the ignition switch in the ON or START position, the fog lamps will illuminate when the driver places the front fog lamp switch in the ON position. The dash integration module (DIM) controls the fog lamp relay coil. When the driver turns ON the front fog lamp switch, the switch momentarily grounds the front fog lamp input circuit of the DIM. In response to this input, the DIM grounds the control circuit of the fog lamp relay. The fuse block - underhood supplies battery positive voltage to the switch circuit of the front fog lamp relay. Ignition voltage is available to the fog lamp relay coil when the key is in the ON or START position. When the DIM grounds the control circuit the relay coil energizes, closing the switch contacts. Current then flows from the fog lamp relay switch to both front fog lamps. Both front fog lamps are permanently grounded at G104 The state of the front fog lamps will be retained when the ignition is cycled off and on.

The DIM will turn ON the park lamps when the fog lamps are ON and send a class 2 message to the instrument panel cluster (IPC) to enable the fog lamp indicator. The front fog lamps will deactivate when either the flash-to-pass or the high beam headlamps are turned on. For vehicles exported to Japan or any European Country except Norway or Sweden the fog lamps remain illuminated with the operation of the high beam headlamps or flash-to-pass. The fog lamps are deactivated in Norway and Sweden when the low or high beam headlamps are turned ON.