Lincoln Navigator: Exterior Lighting / Exterior Lighting. Description and Operation

System Operation

Headlamps

Overview

The LED headlamp system consists of multiple non-replaceable Light Emitting Diodes (LEDs) focused through projector lenses. Headlamp low beams illuminate through both the inner and outer lenses. When high beams are selected, the outer lens Light Emitting Diodes (LEDs) illuminate with an increased intensity. The LED DRL /front parking lamps are integrated into the headlamp assembly below the high and low beam Light Emitting Diodes (LEDs) and are not individually replaceable.

When the LH steering column multifunction switch is pulled briefly, the high beam Light Emitting Diodes (LEDs) briefly illuminate for the flash-to-pass function. If the LH steering column multifunction switch is pushed into the high beam position, the high beam Light Emitting Diodes (LEDs) illuminate until the LH steering column multifunction switch is returned to the center position.

The headlamps may be equipped with automatic headlamp leveling. The headlamp beam height is automatically adjusted according to vehicle load, speed, acceleration and braking. Automatic headlamp leveling is activated when the headlamp switch is in the HEADLAMPS or AUTOLAMPS position.

System Diagram

E371371 *.sttxt { visibility: hidden; } *.stcallout { visibility: visible; } 1 BCM 2 SCCM 3 LH Steering Column Multifunction Switch 4 IPM-A 5 HCM 6 PCM 7 Headlamp Switch 8 GWM 9 ABS 10 (if equipped with automatic headlamp leveling) 11 LH Headlamp 12 RH Headlamp 13 Ignition or Start/Stop Switch

Item	Description
1	BCM
2	SCCM
3	LH steering column multifunction switch
4	IPMA
5	HCM
6	PCM
7	Headlamp switch
8	GWM
9	ABS module
10	(if equipped with automatic headlamp leveling)
11	LH headlamp
12	RH headlamp
13	Ignition or start/stop switch

Network Message Chart

  BCM Network Input Messages

Broadcast Message	Originating Module	Message Purpose
Headlamp flash to pass status	SCCM	Indicates to the BCM a request for the high beams or flash-to-pass.

  SCCM Network Input Messages

Broadcast Message	Originating Module	Message Purpose
Auto high beam request	IPMA	Indicates to the SCCM a request for the high beams based on the IPMA camera input.

Low Beams

The headlamp switch sends a status message over the LIN circuit to the BCM to indicate the headlamp switch status (position or a fault with the headlamp switch). The BCM turns the parking lamps and headlamps on when the ignition is in RUN and the BCM detects a fault from the headlamp switch or wiring. This is normal behavior of the BCM when a fault has been detected with the inputs from the headlamp switch.

When the BCM receives a message requesting the headlamps on, it supplies voltage to the headlamp mounted LDCM . The LDCM sends voltage to the low beam Light Emitting Diodes (LEDs) in each headlamp assembly.

The LDCM is mounted to the outside of the headlamp assembly and is individually replaceable.

The BCM also provides Field Effect Transistor (FET) protection of the low beam output circuits. When an excessive current draw is detected, the BCM disables the affected circuit driver. For additional information on BCM Field Effect Transistor (FET) protection,
Refer to: Module Controlled Functions - System Operation and Component Description (419-10 Multifunction Electronic Modules, Description and Operation).

High Beams

The SCCM monitors the LH steering column multifunction switch for a high beam request. When the LH steering column multifunction switch is in the HIGH BEAMS position, the SCCM sends a message over the HS-CAN2 to the GWM , then the GWM sends the message to the BCM over the HS-CAN1 .

When the low beams are on and the BCM receives a request for high beams:

• the low beam Light Emitting Diodes (LEDs) remains powered on and high beam Light Emitting Diodes (LEDs) are also illuminated. This changes the headlamp beam pattern to illuminate a greater distance.
• the BCM sends a high beam request to the GWM through the HS-CAN1 circuit.
• the GWM sends the high beam request to the HCM through the FD-CAN circuit.
• the HCM sends the high beam request to the headlamp mounted LDCM through a private CAN circuit.

Flash-To-Pass

The SCCM monitors the LH steering column multifunction switch for a flash-to-pass request. When the LH steering column multifunction switch is in the FLASH-TO-PASS position, the SCCM sends a message over the HS-CAN2 to the GWM then the GWM sends the message to the BCM over the HS-CAN1 .

When the ignition is in RUN and the flash-to-pass is requested, the high beams are activated as long as the LH steering column multifunction switch is held in the flash-to-pass position.

Automatic High Beams

The automatic high beam system uses an interior rear view mirror mounted camera to monitor surrounding traffic conditions and high beam usage. The IPMA communicates light information over the FD-CAN to the GWM then the GWM sends the information to the BCM over the HS-CAN1 .

The automatic high beam feature is active only when the headlamp switch is in the AUTOLAMPS position.

During nighttime driving, the automatic high beam system automatically turns the high beams on if it is dark enough and no other traffic is present. When the system detects an approaching vehicle's headlamps or a preceding vehicle's rear lamps, the system turns off the high beams. When the approaching vehicle's headlamps or the preceding vehicle's rear lamps are no longer detected, the high beams automatically turn back on.

The IPMA turns the high beam headlamps on when all of the following conditions are met:

• The feature has been enabled using the message center.
• The headlamp switch is in the AUTOLAMPS position and the autolamps feature has turned the exterior lamps on.
• The vehicle speed is greater than 51 km/h (32 mph).
• The IPMA determines the ambient lighting conditions are dark enough.
• The IPMA does not detect any light source that can be interpreted as an illuminated vehicle lamp.

The IPMA turns the high beams off if any of the following occur:

• The IPMA detects any light source that can be interpreted as an illuminated vehicle lamp.
• The IPMA determines the ambient lighting conditions are not dark enough.
• The vehicle speed falls below 44 km/h (27 mph).
• The autolamps are turned off.
• The IPMA determines the view is blocked.

Headlamp Exit Delay

When the ignition is OFF and the LH steering column multifunction switch is placed in the FLASH-TO-PASS position and released, the parking lamps and low beams are illuminated. They remain illuminated until:

• 3 minutes have elapsed with a door open.
• 30 seconds have elapsed after all doors are closed.
• the LH steering column multifunction switch is placed in the flash-to-pass position again.
• the ignition switches to RUN.

Within the 30 second delay and all the doors closed, opening any door results in the 3 minute timer restarting.

Automatic Headlamp Leveling

The headlamp beam height is automatically adjusted according to vehicle load, speed, acceleration and braking data received from the ABS module, PCM , LH front suspension height sensor and LH rear suspension height sensor.

The front lighting uses a HCM to command the up/down aiming of the headlamp Light Emitting Diodes (LEDs) through the headlamp proprietary CAN to the headlamp assemblies.

The headlamp mounted LDCM receives the messages through the headlamp proprietary CAN from the HCM .

Depending on the inputs received (steering wheel angle and vehicle speed for example), the HCM can command the height at which the headlamp LED is aimed (up or down) to improve nighttime visibility. Automatic headlamp leveling is activated when the headlamp switch is in the HEADLAMPS or AUTOLAMPS position.

When the headlamp mounted LDCM and HCM first receive ignition ON status over CAN , the headlamp mounted LDCM commands the headlamps down then up to initialize the system.

DRL

Overview

The DRL system illuminates the LED DRL /front parking lamps at full intensity in the headlamp assembly when the ignition is on, the headlamp switch is in the OFF or AUTOLAMPS position and the headlamps have not been turned on by the autolamp system.

System Diagram

E371369 *.sttxt { visibility: hidden; } *.stcallout { visibility: visible; } 1 BCM 2 Headlamp Switch 3 Ignition or Start/Stop Switch 4 Headlamp 5 LED DRL/Front Parking Lamps 6 LDCM 7 GWM 8 HCM

Item	Description
1	BCM
2	Headlamp switch
3	Ignition or start/stop switch
4	Headlamp
5	LED front turn/parking lamps
6	LDCM
7	GWM
8	HCM

DRL

The BCM monitors the ignition status, the headlamp switch and autolamp status.

When the BCM requests the DRL on:

• the BCM sends a DRL request to the GWM through the HS-CAN1 circuit.
• the GWM sends the DRL request to the HCM through the FD-CAN circuit.
• the HCM sends the DRL request to the headlamp mounted LDCM through a private CAN circuit.
• the LDCM illuminates the LED DRL /front parking lamps at full intensity.

There are two types of DRL , conventional (where it is required) and configurable.

When equipped with conventional DRL , the DRL are active in any headlamp switch position except the HEADLAMPS position.

The conventional DRL are activated when all of the following conditions are met:

• The ignition is ON.
• The headlamps switch is in OFF, PARKLAMPS or AUTOLAMPS position and the headlamps have not been turned on by the autolamp system.
• The transmission is not in PARK.

When equipped with configurable DRL , the DRL may be enabled through the IPC message center. When enabled, the DRL are active only in the AUTOLAMPS headlamp position. When autolamps request the headlamps on, the DRL are deactivated.

The configurable DRL are activated when all of the following conditions are met:

• The ignition is ON.
• The headlamps switch is in AUTOLAMPS position and the headlamps have not been turned on by the autolamp system.
• The transmission is not in PARK.

Autolamps

Overview

The autolamp system provides light sensitive automatic on/off control of the exterior lamps. When the ambient lighting is low enough and the headlamp switch is in the AUTOLAMPS position, the exterior parking and low beam lamps illuminate. The autolamp system keeps the exterior lamps on for a preselected period of time after the ignition is turned off (20 seconds is the factory default setting). The preselected time is adjustable from 0 up to approximately 2 minutes by using the IPC message center controls.

System Diagram

E345868 *.sttxt { visibility: hidden; } *.stcallout { visibility: visible; } 1 BCM 2 Headlamp Switch 3 Light Sensor 4 Low Beams 5 SCCM 6 GWM 7 Wiper/Washer Switch 8 Parking Lamps 9 Ignition or Start/Stop Switch

Item	Description
1	BCM
2	Headlamp switch
3	Light sensor
4	Low beams
5	SCCM
6	GWM
7	Wiper/Washer switch
8	Parking lamps
9	Ignition or start/stop switch

Network Message Chart

  BCM Network Input Messages

Broadcast Message	Originating Module	Message Purpose
Front wiper status	SCCM	The BCM uses the wiper status information for the operation of the wiper activated headlamps feature.

Autolamps

The BCM monitors the light sensor with a voltage signal. The light sensor input to the BCM varies with the ambient light conditions.

The BCM monitors the headlamp switch circuits to indicate the headlamp switch position.

When the BCM receives a headlamp switch status indicating a request for the autolamps, the BCM monitors the light sensor for the ambient light condition. If the BCM determines the ambient light level is dark, the BCM illuminates the exterior parking and low beam lamps

Headlamps On With Wipers On Function

When the headlamp switch is in the autolamps position, the exterior lamps turn on when the front wipers are in low or high. This feature does not activate the exterior lamps during a mist wipe, while the wipers are on to clear washer fluid during a wash condition or if the wipers are in automatic or intermittent modes.

The exterior lamps turn off when the ignition switches off, the headlamp switch is placed in the OFF position, or the front wipers are turned off. The exception to this is when the exterior lights are on because of darkness determined by the autolamp system.

Stoplamps

Overview

The stoplamp switch is part of the EBB . The EBB is an integrated function of the ABS / HCU assembly and is controlled by the ABS module. The rear lamps and high mounted stoplamp are illuminated when the brake pedal is applied.

System Diagram

E369490 *.sttxt { visibility: hidden; } *.stcallout { visibility: visible; } 1 BCM 2 LH Rear Lamp Assembly 3 High Mounted Stoplamp 4 RH Rear Lamp Assembly 5 PCM 6 GWM

Item	Description
1	BCM
2	LH rear lamp assembly
3	High mounted stoplamp
4	RH rear lamp assembly
5	PCM
6	GWM

Stoplamps

The BCM monitors the input from the ABS module. When the brake pedal is applied, the ABS module sends voltage to the BCM , indicating a request for the stoplamps. The BCM then supplies voltage to the stoplamps.

The BCM uses 3 separate output circuits. The LH stoplamp output circuit, RH stoplamp output circuit and the high-mounted stoplamp output circuit.

The BCM also provides Field Effect Transistor (FET) protection of the stoplamp output circuits. When an excessive current draw is detected, the BCM disables the affected stoplamp circuit driver.
Refer to: Module Controlled Functions - System Operation and Component Description (419-10 Multifunction Electronic Modules, Description and Operation).

Turn Signal and Hazard Lamps

Overview

The LH steering column multifunction switch has 2 detents for the left turn position and 2 detents for the right turn position. When placed in the first detent and released, the corresponding turn signals flash 3 times and turn off. When the LH steering column multifunction switch is moved to the second detent, the turn signal flashes until the steering wheel is turned in the opposite direction and the clockspring (vehicles without adaptive steering) or SCCM (vehicles with adaptive steering) mechanically returns the LH steering column multifunction switch to the neutral position and cancels the turn signal.

The front turn lamp is non-replaceable Light Emitting Diodes (LEDs) mounted in the headlamp assembly.

When the hazard function is active, all the turn lamps flash on and off.

The timed on/off cycle for turn lamps is approximately 70 times per minute.

If a front or rear turn signal lamp is inoperative, the IPC turn lamp indicator fast flashes at approximately 150 times per minute to indicate a lamp outage to the driver (the exterior turn lamps still flash at approximately 70 times per minute).

The timed on/off cycle for the hazard lamps is approximately 70 times per minute, regardless of lamp outage.

Turn signal lamps are located in the front fascia, body mounted rear lamp assemblies, liftgate and the exterior mirrors.

System Diagram

E371373 *.sttxt { visibility: hidden; } *.stcallout { visibility: visible; } 1 SCCM 2 GWM 3 Hazard Switch 4 BCM 5 LH Exterior Mirror 6 RH Exterior Mirror 7 DDM 8 PDM 9 LH Steering Column Multifunction Switch 10 RH Rear Body Mounted Turn Lamp 11 LH Rear Body Mounted Turn Lamp 12 RH Front Turn Lamp 13 LH Front Turn Lamp 14 RH Headlamp 15 LH Headlamp 16 LH Rear Liftgate Mounted Turn Lamp 17 RH Rear Liftgate Mounted Turn Lamp 18 LDCM 19 LDCM 20 Ignition or Start/Stop Switch 21 HCM

Item	Description
1	SCCM
2	GWM
3	Hazard switch
4	BCM
5	LH exterior mirror
6	RH exterior mirror
7	DDM
8	PDM
9	LH steering column multifunction switch
10	RH rear body mounted turn lamp
11	LH rear body mounted turn lamp
12	RH front turn lamp
13	LH front turn lamp
14	RH headlamp
15	LH headlamp
16	LH rear liftgate mounted turn lamp
17	RH rear liftgate mounted turn lamp
18	LDCM
19	LDCM
20	Ignition or Start/Stop Switch
21	HCM

Network Message Chart

  BCM Network Input Messages

Broadcast Message	Originating Module	Message Purpose
Turn signal switch status	SCCM	Indicates the turn signal stalk position on the LH steering column multifunction switch (left/right lane change or turn signal on or off). The BCM activates the left/right turn signals based on this input.

  DDM and PDM Network Input Messages

Broadcast Message	Originating Module	Message Purpose
Turn indication request	BCM	A command to the DDM or PDM to activate/deactivate the exterior mirror turn indicator.

Front Turn Signals

The SCCM monitors the LH steering column multifunction switch position. When the LH steering column multifunction switch is in the LH TURN or RH TURN position, the SCCM sends a message over the HS-CAN2 to the GWM then the GWM sends the message to the BCM over the HS-CAN1 indicating a request for the LH or RH turn signal.

When the BCM requests the turn signals on:

• the BCM sends a turn signal request to the GWM through the HS-CAN1 circuit.
• the GWM sends the turn signal request to the HCM through the FD-CAN circuit.
• the HCM sends the turn signal request to the headlamp mounted LDCM through a private CAN circuit.
• the LDCM supplies on/off voltage to the front fascia mounted turn signal lamp.

If a front turn signal lamp is inoperative, the IPC turn lamp indicator fast flashes at approximately 150 times per minute to indicate a bulb outage to the driver (the exterior turn lamps still flash at approximately 70 times per minute).

Rear Turn Signals

The SCCM monitors the LH steering column multifunction switch position. When the LH steering column multifunction switch is in the LH TURN or RH TURN position, the SCCM sends a message over the HS-CAN2 to the GWM then the GWM sends the message to the BCM over the HS-CAN1 indicating a request for the LH or RH turn signal.

When the BCM receives a request for a turn signal, the BCM supplies on/off voltage to the appropriate turn lamps.

For the body mounted rear lamp turn signals only, during normal operation, when the BCM supplies voltage to the rear turn lamp assembly, the rear lamp assembly sends the same voltage back to the BCM through the outage circuit. If the Light Emitting Diodes (LEDs) are inoperative the BCM does not receive this voltage feedback through the outage circuit.

If a rear turn signal lamp is inoperative, the IPC turn lamp indicator fast flashes at approximately 150 times per minute to indicate a bulb outage to the driver (the exterior turn lamps still flash at approximately 70 times per minute).

The BCM also provides Field Effect Transistor (FET) protection of the turn lamp output circuits. When an excessive current draw is detected, the BCM disables the affected turn lamp circuit driver. For additional information on BCM Field Effect Transistor (FET) protection,
Refer to: Module Controlled Functions - System Operation and Component Description (419-10 Multifunction Electronic Modules, Description and Operation).

Mirror Turn Signals

The SCCM monitors the LH steering column multifunction switch position. When the LH steering column multifunction switch is in the LH TURN or RH TURN position, the SCCM sends a message over the HS-CAN2 to the GWM then the GWM sends the message to the BCM over the HS-CAN1 indicating a request for the LH or RH turn signal.

When the BCM receives a request for a turn signal, the BCM sends a turn indicator command message over the HS-CAN1 to the GWM then the MS-CAN to the door modules for the exterior mirror turn lamps.

Hazard Lamps

The BCM sends a voltage signal to the hazard flasher lamp switch to monitor for a hazard lamp function request. When the hazard flasher lamp switch is pressed, the voltage signal is routed to ground, indicating a request to activate or deactivate the hazard lamp function.

Parking, Rear, and License Plate Lamps

Overview

The LED DRL /front parking lamps in the headlamp assembly are used as parking lamps and illuminated at a reduced intensity when the parking lamps or headlamps are activated. The LED DRL /front parking lamps are non-replaceable Light Emitting Diodes (LEDs) mounted in the headlamp assembly.

Parking lamps are located in the headlamp assemblies, body mounted rear lamp assemblies, liftgate lamp and license plate lamps.

System Diagram

E371372 *.sttxt { visibility: hidden; } *.stcallout { visibility: visible; } 1 BCM 2 Headlamp Switch 3 Rear Body Mounted Parking Lamp 4 Rear Liftgate Mounted Parking Lamp 5 License Plate Lamps 6 RH Headlamp 7 LED DRL/Front Parking Lamps 8 LDCM 9 Front Side Marker LEDs 10 Except China 11 Ignition or Start/Stop Switch 12 GWM 13 HCM 14 LH Headlamp 15 LED DRL/Front Parking Lamps 16 LDCM 17 Front Side Marker LEDs 18 Except China

Item	Description
1	BCM
2	Headlamp switch
3	Rear body mounted parking lamp
4	Rear liftgate mounted parking lamp
5	License plate lamps
6	RH headlamp
7	LED DRL /front parking lamps
8	LDCM
9	Front side marker Light Emitting Diodes (LEDs)
10	Except China
11	Ignition or start/stop switch
12	GWM
13	HCM
14	LH headlamp
15	LED DRL /front parking lamps
16	LDCM
17	Front side marker Light Emitting Diodes (LEDs)
18	Except China

Parking Lamps

The headlamp switch sends a status message over the LIN circuit to the BCM to indicate the headlamp switch status (position or a fault with the headlamp switch). The BCM turns the parking lamps and headlamps on when the ignition is in RUN and the BCM detects a fault from the headlamp switch or wiring. This is normal behavior of the BCM when a fault has been detected with the inputs from the headlamp switch.

For front parking lamps, when the BCM requests the parking lamps on:

• the BCM sends a parking lamps request to the GWM through the HS-CAN1 circuit.
• the GWM sends the parking lamps request to the HCM through the FD-CAN circuit.
• the HCM sends the parking lamps request to the headlamp mounted LDCM through a private CAN circuit.
• the LDCM illuminates the LED DRL /front parking lamps at a reduced intensity.

For rear parking lamps, when the BCM receives a request for a parking lamps, the BCM supplies voltage to the rear parking lamps.

The BCM also provides Field Effect Transistor (FET) protection of the parking lamps output circuits. When an excessive current draw is detected, the BCM disables the affected parking lamps circuit driver. For additional information on BCM Field Effect Transistor (FET) protection,
Refer to: Module Controlled Functions - System Operation and Component Description (419-10 Multifunction Electronic Modules, Description and Operation).

Approach Detection

The approach detection feature is used to passively activate the illuminated entry feature while approaching the vehicle. Illuminated entry includes ramping up the illumination of the vehicles parking lamps.

Fog Lamps

Overview

The front fog lamps can be turned on when the ignition is in ON by placing the headlamp switch in any position except OFF and pressing the front fog lamp switch.

The rear fog lamps can be turned on when the ignition is in ON by placing the headlamp switch in the HEADLAMPS position and pressing the rear fog lamp switch. The rear fog lamps are located in the rear bumper.

System Diagram

E371370 *.sttxt { visibility: hidden; } *.stcallout { visibility: visible; } 1 SCCM 2 GWM 3 BCM 4 LH Steering Column Multifunction Switch 5 RH Headlamp 6 LH Headlamp 7 LDCM 8 LDCM 9 HCM 10 Headlamp Switch 11 Ignition or Start/Stop Switch 12 LH Rear Fog Lamp 13 RH Rear Fog Lamp 14 LH Front Fog Lamp 15 RH Front Fog Lamp 16 Except North America

Item	Description
1	SCCM
2	GWM
3	BCM
4	LH steering column multifunction switch
5	RH headlamp
6	LH headlamp
7	LDCM
8	LDCM
9	HCM
10	Headlamp switch
11	Ignition or start/stop switch
12	LH rear fog lamp
13	RH rear fog lamp
14	LH front fog lamp
15	RH front fog lamp
16	Except North America

Fog Lamps

The headlamp switch sends a status message over the LIN circuit to the BCM to indicate the headlamp switch status (position or a fault with the headlamp switch). The BCM turns the parking lamps and headlamps on when the ignition is in RUN and the BCM detects a fault from the headlamp switch or wiring. This is normal behavior of the BCM when a fault has been detected with the inputs from the headlamp switch.

When the ignition is in ON, the BCM supplies voltage to each front fog lamp.

When the BCM receives input from the headlamp switch indicating a request for the front fog lamps, the BCM requests the front fog lamps on and:

• the BCM sends a front fog lamps request to the GWM through the HS-CAN1 circuit.
• the GWM sends the front fog lamps request to the HCM through the FD-CAN circuit.
• the HCM sends the front fog lamps request to the headlamp mounted LDCM through a private CAN circuit.
• the LDCM supplies a signal voltage to the front fog lamp.

When the BCM receives input from the headlamp switch indicating a request for the rear fog lamp, the BCM provides voltage to the front fog lamp.

The BCM also provides an Field Effect Transistor (FET) protection of the front fog lamps voltage supply circuits and the rear fog lamp output circuits. When an excessive current draw is detected, the BCM disables the fog lamp output circuit drivers.
Refer to: Module Controlled Functions - System Operation and Component Description (419-10 Multifunction Electronic Modules, Description and Operation).

Reversing Lamps

Overview

When the transmission is placed in REVERSE, the reversing lamp in the liftgate lamp assembly is illuminated.

System Diagram

E369491 *.sttxt { visibility: hidden; } *.stcallout { visibility: visible; } 1 Reversing Lamps 2 TR Sensor 3 Ignition or Start/Stop Switch 4 BCM 5 PCM 6 GWM

Item	Description
1	Reversing lamps
2	TR sensor
3	Ignition or start/stop switch
4	BCM
5	PCM
6	GWM

Network Message Chart

  BCM Network Input Messages

Broadcast Message	Originating Module	Message Purpose
Reverse	PCM	Indicates the transmission is in reverse gear to the BCM . When the transmission is in REVERSE and the ignition in RUN, the BCM provides voltage to the reversing lamps.

Reversing Lamps

When the transmission is in REVERSE, the PCM sends a message over the FD-CAN to the GWM then the GWM sends the information to the BCM over the HS-CAN1 indicating the transmission is in REVERSE. The BCM provides voltage to the reversing lamp when it receives the message that the transmission is in REVERSE and the ignition is in RUN.

The BCM also provides Field Effect Transistor (FET) protection of the reversing lamp output circuit. When an excessive current draw is detected, the BCM disables the affected reversing lamps circuit driver.
Refer to: Module Controlled Functions - System Operation and Component Description (419-10 Multifunction Electronic Modules, Description and Operation).

Trailer Lamps

Overview

The BCMC (also known as the BJB ) trailer tow parking lamps relay (non-serviceable) supplies voltage to the trailer parking lamps.

The BCMC trailer tow reversing lamps relay (non-serviceable) supplies voltage to the trailer tow reversing lamps when the vehicle reversing lamps are commanded on.

The TRM supplies voltage to the trailer stop/turn lamps.

The TRM provides voltage to the trailer tow connector for trailer battery charging when all of the following are true:

• The TRM detects that a trailer is connected.
• The ignition is in ACC or ON.
• The BCM load shed strategy is not active (a message is displayed in the instrument cluster, such as Low Battery Features Temporarily Turned Off or Turn Power Off To Save Battery, to indicate that BCM load shed strategy is active).

System Diagram

E369492 *.sttxt { visibility: hidden; } *.stcallout { visibility: visible; } 1 TRM 2 Trailer Tow Connector 3 Trailer Tow Reversing Lamp Relay 4 Trailer Tow Parking Lamp Relay 5 BCM 6 GWM 7 SCCM 8 LH Steering Column Multifunction Switch 9 Headlamp Switch 10 PCM 11 BCMC

Item	Description
1	TRM
2	Trailer tow connector
3	Trailer tow reversing lamp relay
4	Trailer tow parking lamp relay
5	BCM
6	GWM
7	SCCM
8	LH steering column multifunction switch
9	Headlamp switch
10	PCM
11	BCMC

Network Message Chart

  TRM Network Input Messages

Broadcast Message	Originating Module	Message Purpose
Turn signal switch status	SCCM	A command to the TRM to activate/deactivate the turn indicator output to the trailer tow connector.
Stoplamp request	BCM	A command to the TRM to activate/deactivate the stop lamps output to the trailer tow connector.
Parklamp status	GWM	A command to the TRM to activate/deactivate the park lamps output to the trailer tow connector.

Trailer Stop-Turn Lamps

The SCCM monitors the LH steering column multifunction switch position. When the LH steering column multifunction switch is in the left or right turn position, the SCCM sends a message over the HS-CAN2 to the GWM then the GWM sends the message to the BCM over the HS-CAN1 indicating a request for the LH or RH turn signal.

When the BCM receives a request for a turn signal, the BCM sends a turn indicator command message over the HS-CAN1 to the GWM , then the GWM sends a turn indicator command message over the HS-CAN3 to the TRM to activate the requested stop/turn indicator output to the trailer tow connector.

When the BCM receives input from the stoplamp switch indicating that the brake pedal is being pressed, the TRM receives a stoplamp activation message over the HS-CAN3 to activate the requested stop/turn indicator output to the trailer tow connector.

Trailer Parking Lamps

The headlamp switch sends a headlamp switch status message over the LIN to the BCM to indicate the headlamp switch status (position or a fault with the headlamp switch).

When the parking lamps or headlamps position is selected, the BCM provides a ground path to the BCMC parking lamps trailer tow relay. When the BCM provides ground the parking lamps trailer tow relay, the relay is energized and the relay provides parking lamp voltage to the trailer tow connector.

Trailer Reversing Lamps

When the transmission is in REVERSE, the PCM sends a message FD-CAN to the GWM then the GWM sends the information over the HS-CAN1 to the BCM indicating the transmission is in REVERSE. The BCM provides voltage to the reversing lamps trailer tow relay (integral to the BCMC ) when it receives the message that the transmission is in REVERSE and the ignition is in RUN. When the BCM provides voltage to the reversing lamps trailer tow relay, the relay is energized and the relay provides reversing lamp voltage to the trailer tow connector.

Trailer Battery Charging

NOTE: For vehicles equipped with push-button start, the trailer battery charging output is disabled when the drivers door is ajar.

The TRM provides voltage to the trailer tow connector for trailer battery charging when all the following are true:

• The TRM detects that a trailer is connected.
• The ignition is in ACC or ON.
• The BCM load shed strategy is not active (a message is displayed in the instrument cluster, such as Low Battery Features Temporarily Turned Off or Turn Power Off To Save Battery, to indicate that BCM load shed strategy is active).

Trailer And Lamp Outage Detection

The TRM senses resistance in the LH and RH brake/turn signal output circuits that is within a calibrated range. If the resistance is higher than the calibrated range on either the LH or RH brake/turn signal output circuits, the TRM reports a trailer lamp fault message. If the resistance is lower than the calibrated range on one of the LH or RH brake/turn signal output circuits when the brake is pressed during the ignition cycle, the TRM reports a trailer lamp fault message and the TRM sets a DTC .

Field Effect Transistor (FET) Protection

The TRM utilizes a Field Effect Transistor (FET) protective circuit strategy for its lamp output circuits. Output loads (current level) are monitored for excessive current (typically short circuits) and are shut down (turns off the voltage or ground provided by the module) when a fault event is detected.

For information on Field Effect Transistor (FET) protective circuit strategy,
Refer to: Module Controlled Functions - System Operation and Component Description (419-10 Multifunction Electronic Modules, Description and Operation).

Component Description

Headlamp Assembly

Exterior lamps are vented to accommodate normal changes in pressure. Condensation can be a natural by-product of this design. When moist air enters the lamp assembly through the vents, there is a possibility that condensation can occur if the temperature is cold. When normal condensation occurs, a thin mist forms on the interior of the lens. The thin mist eventually clears and exits through the vents during normal operation. The amount of time it takes to clear the lens of acceptable mist varies with ambient humidity and lamp types. Normal condensation clears from any lamp in 48 hours under dry conditions.

Do not replace a lamp assembly with acceptable levels of condensation such as:

• presence of thin mist (no streaks, drip marks or droplets are present)
• fine mist covers less than 50% of the lens

Examples of unacceptable moisture (usually caused by a lamp housing leak):

• water puddling inside the lamp
• large water droplets, drip marks or streaks present on the interior of the lens

Headlamp Switch

The headlamp switch sends a headlamp switch status message over the LIN to the BCM to indicate the headlamp switch status (position or a fault with the headlamp switch).

Light Sensor

The BCM sends a voltage signal to the light sensor. The light sensor provides resistance between the voltage signal and ground. The resistance varies depending on the amount of ambient light detected by the light sensor. The brighter the ambient light, the lower the resistance. By varying the resistance, the BCM can determine the amount of ambient light.

Stoplamp Switch

The stoplamp switch is part of the EBB . The EBB is an integrated function of the ABS / HCU assembly and is controlled by the ABS module.