Exterior Lighting

EXTERIOR LIGHTING

NOTE: The front electronic module (FEM), the rear electronic module (REM) and the instrument cluster must be reconfigured before installing a new module.

The vehicle electronic functions are divided into zones. The FEM controls the front portion of the vehicle and the REM controls the rear portion of the vehicle. These systems rely on the standard corporate protocol (SCP) communication network in order to transmit and receive signals. It is very important to understand:
- where the input (command) originates from.
- all information (messages) necessary in order for a feature to operate.
- which module(s) receive(s) the input or command message.
- if the module which received the input (message) controls the output of the feature, or does it output a message over the SCP communication network to another module.
- which module controls the output of the feature.

Exterior Lighting
The exterior lighting outputs are zone controlled by the FEM and REM. The front exterior lights are controlled by the FEM and the rear exterior lights are controlled by the REM. An additional function of the lighting system is a lamp outage function which indicates to the driver if certain exterior bulbs are not functioning. With a bulb inoperative, the FEM or REM will send a message to the instrument cluster and message center (if equipped with the message center), which will indicate to the driver that the lamp is inoperative with a lamp out indicator (with the message center a message will be displayed). All exterior lighting is powered by the switched system power (SSP) feature. A failure of all or any of the SSP features will cause inoperative exterior lighting. When diagnosing exterior lighting, it is essential to determine if all related symptoms and DTCs are controlled by the SSP feature.

Switched System Power (SSP)
The SSP is utilized by both the FEM and REM. This function removes power from relays that provide power to the exterior lamps, interior lamps and power door locks. This is only accomplished when both the FEM and the REM are in sleep mode. The sleep function of the FEM and REM places the modules in sleep mode when the ignition switch is in the OFF position, and no wake up (input) signals occur for 30 minutes. The module will not sleep if the parking lamps or the hazard lamps are active. The following relays are controlled by the SSP function: SSP1, SSP2, SSP3 and SSP4. When either the FEM or REM are not in sleep mode, all SSP relays will be energized. When energized, each relay will supply power to multiple features/functions.

Headlamps
The headlamps are controlled by the FEM and the instrument cluster. The headlamp and multifunction switches are hard-wired to the instrument cluster. When the headlamp switch is in any position, the instrument cluster will send a command to the FEM through the SCP communication network. The FEM will process this information and output the appropriate command to the headlamps, which are hard-wired to the FEM (if equipped with high intensity discharge (HID) headlamps, the HID relays are hard-wired to and controlled by the FEM). This is the same for the low and high beams and flash-to-pass position. Either low or high beam will provide a lamp outage indication (halogen bulbs only). Fault management of the headlamps will provide some headlamp functionality. In the event of all multifunction switch, all headlamp switch or ignition switch invalid or missing data failures, the low beams will be illuminated. There is also a headlamp battery saver feature. This feature turns off the headlamps ten minutes after the ignition switch is turned OFF when the headlamp switch is in the headlamps ON position. The battery saver does not function if the headlamp switch is in the parking lamps ON position.

NOTE: Daytime running lamps (DRL) feature is available for Canadian vehicles only.

Autolamps and DRL are 2 functions which the FEM may be configured to include.

Autolamps
The autolamps are controlled by the headlamp switch, photocell sensor, instrument cluster and the FEM. The headlamps may be in the high or low beam position depending on the multifunction switch position. When the headlamp switch is in the autolamp position, the instrument cluster sends an ON or OFF command to the FEM, depending on the signal from the autolamp sensor. The FEM processes this information and outputs the appropriate command to the headlamps. The headlamps are hard-wired to the FEM. The autolamps remain ON for approximately 20 seconds to 3 minutes (depending on customer preferences) after the ignition switch is changed from the ON position to the ACC or OFF position.

Turn Signal, Cornering and Hazard Lamps
The LH and RH front turn signal, LH and RH rear turn signal outputs, and front and rear hazard lamp outputs are controlled by the FEM and REM. The multifunction switch and the hazard switch are hard-wired to the instrument cluster. When the switch is in the left- or right-turn position, or the hazard switch is in the ON position, the instrument cluster sends a command through the standard corporate protocol (SCP) network to the FEM and REM, which processes this information and outputs the appropriate command to the front and rear turn signal and hazard lamps. All turn signal lamps will provide lamp outage indication.

Parking, Rear or License Lamps
For the LH and RH rear parking, license, and LH and RH front parking lamps, outputs are controlled by the FEM and REM. The headlamp switch is hard-wired to the instrument cluster. When the headlamp switch is in the headlamps ON or parking lamps ON position, the instrument cluster sends a command via the network link to the FEM and REM. The FEM and REM process this information and output the appropriate command to the parking or license lamps, which are hard-wired to the FEM and REM. Only the left and right rear lamps will provide lamp outage indication. Fault management of the parking lamps provides rear parking lamp functionality in the event of certain multifunction switch, headlamp switch, ignition switch, FEM or REM failures.

Fog Lamps
The fog lamps are controlled by the headlamp switch. The switch toggles the fog lamps between on and off. When activated, the switch sends voltage to the instrument cluster. The instrument cluster sends a signal to the FEM which activates the fog lamp.

Reversing Lamps
The reversing lamps are controlled by the REM and powertrain control module (PCM). The PCM sends a message through the SCP communication network to the REM indicating the transmission is in REVERSE. The REM processes this information and outputs the command to the reversing lamps which are hard-wired to the REM. Fault management of the reversing lamps will provide limited reversing lamp functionality. In the event of missing or invalid transmission data, the reversing lamps remain in the last state of operation prior to the failure for one key cycle. In the event of invalid or missing data for the ignition switch, the lamps will work in relation to PRNDL messages.