Lincoln Navigator: Parking Aid - Vehicles With: Active Park Assist / Parking Aid - System Operation and Component Description. Description and Operation

System Operation

Overview - Active Park Assist

NOTE: Vehicles equipped with active park assist use a different parking aid sensor. The IPMA supplies a 12v reference voltage and a ground. The signal circuit is a LIN used to comunicate the sensor data with the IPMA .

The active park assist system is a supplementary parking system that assists the operator with the task of parking in three ways:

• Parallel Park Assist is activated by pushing the active park assist switch - Detects the available parking space and automatically maneuvers the vehicle into the space by controlling the steering, accelerator, brakes and gear selection.
• Perpendicular Park Assist is activated by pushing the active park assist switch - Detects an available parking space and automatically maneuvers the vehicle into the space by controlling the steering, accelerator, brakes and gear selection.
• Parallel Park Out Assist is activated by pushing the active park assist switch - Analyzes the parking space currently occupied by the vehicle and automatically maneuvers the vehicle out of the space by controlling the steering, accelerator, brakes and gear selection.

The system visually and/or audibly instructs the operator to park the vehicle through messages in the centerstack infotainment display and audio system warning chimes.

The IPMA uses input from the active park assist sensors, parking aid sensors and a geometrical equation to determine whether the vehicle fits in the parking space and to determine the correct steering angles to request from the PSCM during the parking maneuvers. The system visually and/or audibly instructs the operator to park the vehicle through messages in the centerstack infotainment display and audio system warning chimes. The Active Park Assist system then maneuvers the vehicle into the desired parking space or manuevers out of the parking space.

Active Park Assist

System Diagram

*.sttxt { visibility: hidden; } *.stcallout { visibility: visible; } 1 Park Assist Switch 2 LH Front Outer Sensor 3 LH Front Inner Sensor 4 RH Front Inner Sensor 5 RH Front Outer Sensor 6 LH Rear Outer Sensor 7 LH Rear Inner Sensor 8 RH Rear Inner Sensor 9 RH Rear Outer Sensor 10 LH Front Side Sensor 11 RH Front Side Sensor 12 LH Rear Side Sensor 13 RH Rear Side Sensor 14 GWM 15 PCM 16 PSCM 17 ABS 18 TCCM 19 BCM 20 SCCM 21 TCU 22 APIM 23 IPC 24 TRM 25 DSP 26 Speakers 27 Display Unit 28 IPMA E372010

Item	Description
1	Park Assist Switch
2	LH Front Outer Sensor
3	LH Front Inner Sensor
4	RH RH Front Inner Sensor
5	RH Front Outer Sensor
6	LH Rear Outer Sensor
7	LH Rear Inner Sensor
8	RH Rear Inner Sensor
9	RH Rear Outer Sensor
10	LH Front Side Sensor
11	RH Front Side Sensor
12	LH Rear Side Sensor
13	RH Rear Side Sensor
14	GWM
15	PCM
16	PSCM
17	ABS
18	TCCM
19	BCM
20	SCCM
21	TCU
22	APIM
23	IPC
24	TRM
25	DSP
26	Speakers
27	Display Unit
28	IPMA

Network Message Chart

  IPMA Network Input Messages

Broadcast Message	Originating Module	Message Purpose
ABS active	ABS module	Disables the active park assist if an ABS activation occurs.
Ambient air temperature filtered	PCM	Used to temperature compensate the parking aid sensors.
Active park assist steering angle control status	PSCM	Provides the steering angle status confirmation to the IPMA .
Active park assist mode request	APIM	Allows the driver to change the parking aid settings through the centerstack infotainment display.
EPAS failure	PSCM	Disables the active park assist if an EPAS failure occurs.
Gear lever position	PCM	Determines the current gear selection.
Stability-traction control event in progress	ABS module	Disables the active park assist if a stability or traction control system activation occurs.
Stability-traction control indicator request	ABS module	Disables the active park assist if a stability or traction control system fault occurs.
Steering pinion angle	PSCM	Determines the current steering angle.
Trailer lamp connected	TRM	Deactivates the system if a trailer is connected.
Turn signal switch status	SCCM	Determines which side of the vehicle the intended parking space is located on.
Vehicle speed	PCM	Disables the active park assist system if the vehicle speed exceeds a preset threshold when the system is active.
Vehicle yaw rate	ABS module	Determines the current vehicle yaw rate.
Wheel rotation count	ABS module	Confirms wheel rotation during active park assist maneuvers.
Wheel rotation direction	ABS module	Confirms wheel rotation direction during active park assist maneuvers.
Wheel speed data	ABS module	Confirms vehicle movement and calculates distance traveled during active park assist maneuvers.

  PSCM Network Input Messages

Broadcast Message	Originating Module	Message Purpose
Active park assist steering angle request	IPMA	Commands the steering angle during active park assist maneuvers.
Steering wheel angle	ABS module	Determines the current steering angle.
Vehicle speed	PCM	Disables the active park assist if vehicle speed is too high during a maneuver.

  IPC Network Input Messages

Broadcast Message	Originating Module	Message Purpose
Active park assist chime request	IPMA	Used by the IPC to generate the chimes for the active park assist system.
Active park assist mode available	IPMA	Used by the IPC to display the active park assist available modes to the driver.
Active park assist status	IPMA	Updates the IPC with the active park assist status.

  APIM Network Input Messages

Broadcast Message	Originating Module	Message Purpose
Active park assist message display	IPMA	Provides parking aid information for the audio system display.
Active park assist mode available	IPMA	Used by the APIM to display the active park assist available modes to the driver.
Active park assist status	IPMA	Updates the APIM with the active park assist status.

  PCM Network Input Messages

Broadcast Message	Originating Module	Message Purpose
Active park assist status	IPMA	Updates the PCM with the active park assist status.
Gear request	IPMA	Controls the vehicle gear.
Vehicle speed request	IPMA	Controls the vehicle speed during parking maneuver.

  ABS Module Network Input Messages

Broadcast Message	Originating Module	Message Purpose
Brake torque request	PCM	Used to slow and stop the vehicle.

Active Park Assist

The IPMA uses the following inputs to calculate vehicle position and distance in relation to the parking space:

• Steering angle
• Vehicle wheel rotation count and direction
• Active park assist sensors
• Parking aid sensors
• Vehicle speed
• Transmission input

The IPMA uses these inputs to command the steering angles required to maneuver the vehicle into or out of a parallel parking space or into a perpendicular parking space.

When the active park assist switch is pressed, the IPMA uses active park assist sensor inputs, parking aid sensor inputs, vehicle speed and transmission selection to determine if the operator is attempting to maneuver the vehicle into or out of a parallel parking space or into a perpendicular parking space.

Pressing and releasing the active park assist switch at any time during an active park assist maneuver disables the active park assist system. If the system is disabled by the operator after the system starts to control the steering, the centerstack infotainment display displays an active park assist canceled message followed by a warning chime.

The IPMA continuously monitors the active park assist sensor signals any time the ignition is on. When no signal is detected from an active park assist sensor, the IPMA sets a DTC .

If an input module fault or other system malfunction is present, the active park assist system is disabled. An active park assist fault message is shown in the centerstack infotainment display and/or in the IPC message center display and a DTC is set in the IPMA . In addition to possible vehicle faults, certain driver actions and vehicle operating conditions can cause the active park assist system to be temporarily disabled.

Certain conditions can cause the active park assist system to incorrectly align the vehicle in the parking space:

• A spare tire installed or one of the tires on the vehicle has significantly more or less treadwear than the other tires.
• The vehicle has been equipped with various accessories (cycle rack, trailer) which are not recognized by the active park assist system.
• The factory-installed tire size is not used on the vehicle.
• Poor ambient weather conditions such as heavy rain or snow.
• The active park assist sensors are damaged or obstructed.
• The curb along the parking space is irregular.
• The vehicle or objects bordering the space are not positioned correctly.
• The parking space dimensions or parked objects position have changed after the vehicle has initially passed the parking space.
• The ambient temperature changes quickly such as the vehicle driven from a heated garage into the cold or just leaving a car wash before the system was activated.
• One of the surrounding parked vehicles has a high or overhanging attachment, such as a salt spreader or a large truck bed, the sensors cannot detect.

Parallel Parking Operation

After the active park assist system is activated and the IPMA has determined the driver is attempting to maneuver the vehicle into a parallel parking space (the active park assist switch is pressed once), the IPMA begins searching for a parking space using the front active park assist sensors. The multifunction switch turn signal input from the SCCM determines which side of the vehicle the IPMA should search for a parking space. When a side is selected the IPMA searches on that side of the vehicle until the active park assist is switched off, the ignition is cycled, or the opposite side is selected by the driver. By default, the IPMA searches for parking spots on the passenger side of the vehicle.

The system measures the available parking spaces and its surroundings as the operator drives by to determine if the vehicle can be maneuvered into the available parking space. The IPMA uses inputs from the front active park assist sensors and the wheel speed and rotation data message to find an acceptable parking space. After a space has been located, a chime is sounded through the audio system and the centerstack infotainment display shows a message informing the driver that a parking space has been located on the left or right side and requesting the driver to pull forward to park. After the driver moves the vehicle forward to the appropriate start position, as determined by the IPMA , the system requests the driver to stop, shift the transmission into neutral and remove hands from the steering wheel. After the transmission is in neutral and no driver input torque on the steering wheel is detected (driver has removed their hands from the wheel), the active park assist system takes control of the steering, acceleration and braking.

The IPMA determines the parallel parking maneuvers are completed based on the final vehicle alignment. The vehicle should be located approximately 0 to 30 cm (12 in) from the street curb if a curb is detected, otherwise the system aligns the vehicle to the spot end object. When the active park assist maneuver is complete, the centerstack infotainment display displays an active park assist finished message followed by an audible chime.

Parallel Park Out Assist Operation

Parallel park out assist is available immediately after a parallel park was completed or after an ignition on. The driver must activate the active park assist system by pressing the active park assist switch once, using the turn signal before the system measures the location, select the side to exit the parking spot. Once the turn signal status is received from the SCCM , the IPMA verifies the indicated side is clear by analyzing the clearance around the vehicle using input from the active park assist sensors and the parking aid sensors. When the indicated side is clear of obstructions, the centerstack infotainment display shows a message informing the driver to remove hands from the steering wheel and shift to neutral, depending on the detected clearances to the front and rear of the vehicle. After the transmission is shifted and no driver input torque on the steering wheel is detected (driver has removed their hands from the wheel), the system slowly pulls out of the parking spot. The IPMA sends the active park assist steering angle request to the PSCM to turn the wheels to an angle which steers the vehicle out of the parallel parking space on the desired side. A vehicle gear and speed request is sent from the IPMA to the PCM . When needed the PCM will send a brake request to the ABS module to slow or stop the vehicle.

The IPMA determines that the parallel park out assist maneuvers are complete when a clear path to exit the parking space is detected. When the maneuver is complete, a chime is played and the centerstack infotainment display shows a message informing the driver to take control of the steering. It remains the responsibility of the driver to check for safe conditions when entering traffic from a parking space.

The parallel park out assist system is only for exiting parallel spots.

Perpendicular Parking Operation

The perpendicular parking feature is available when the active park assist system has been activated (the active park assist switch is pressed twice) and the IPMA has determined the driver is attempting to maneuver the vehicle into a perpendicular parking space. Using the front active park assist sensors, the multifunction turn signal input from the SCCM , the IPMA begins searching for a parking space. If the turn signal is not active, the IPMA defaults to searching on the passenger side of the vehicle.

The system measures the available parking spaces and its surroundings as the operator drives by to determine if the vehicle can be maneuvered into the available parking space. The IPMA uses inputs from the front active park assist sensors and the wheel speed and rotation data message to find an acceptable parking space. After a space has been located, a chime is sounded through the audio system and the centerstack infotainment display shows a message informing the driver that a parking space has been located on the left or right side and requesting the driver to pull forward to park. After the driver moves the vehicle forward to the appropriate start position as determined by the IPMA , the system requests the driver to stop, shift the transmission into neutral and remove hands from the steering wheel. The IPMA begins to reverse the vehicle into the perpendicular parking spot by sending the active park assist steering angle request to the PSCM to turn the wheels to an angle which steers the vehicle into the perpendicular parking space on the desired side. A vehicle gear and speed request is sent from the IPMA to the PCM . When needed the PCM will send a brake request to the ABS module to slow or stop the vehicle.

The IPMA determines the perpendicular parking maneuvers are completed based on the final vehicle alignment. The perpendicular parking aid system attempts to center the vehicle between the two vehicles and align the end vehicle angle with the angle of the parked vehicles. If only one vehicle is detected, the system aligns with that vehicle at a distance of 70 to 90 cm (28 to 35 in) in North America and South America or 55 to 75 cm (22 to 30 in) in Europe and Asia Pacific. When the active park assist maneuver is complete, the centerstack infotainment display displays an active park assist finished message followed by an audible chime.

Parking Aid System

The active park assist system uses input from the audible parking aid system when parking the vehicle. Input from the front and rear parking aid sensors help the IPMA to determine the position of the vehicle in the parking space. For more information on the operation of the audible parking aid system,
Refer to: Parking Aid - System Operation and Component Description (413-13A Parking Aid, Description and Operation).

EPAS Control

The PSCM controls the steering during active park assist maneuvers based on the active park assist steering angle request message received from the IPMA . The PSCM also provides steering column torque data to the IPMA to determine if the driver has placed their hand(s) on the steering wheel while the active park assist system has control of the steering.

Active Park Assist Chimes

The active park assist system chimes are controlled by the IPC . Based on the parking aid chime request message received from the IPMA , the IPC prioritizes the incoming chime request and then commands the ACM or the DSP (if equipped) to sound the chime through the audio system speakers. In the event of an audio system fault, the IPC sounds the chimes through an integral speaker. For more information on the IPC warning chimes,
Refer to: Warning Chimes - System Operation and Component Description (413-01 Instrumentation, Message Center and Warning Chimes, Description and Operation).

Active Park Assist Message Display

Active park assist messages are shown on the centerstack infotainment display. Conditions that can cause the active park assist system to be temporarily unavailable or cause the current active park assist system maneuver to be cancelled are:

Cancellation Event	Audio System Display Message/Audio Chime
Vehicle speed above 18 mph (29 km/h) during the measuring/searching phase for 30 consecutive seconds. Note, the screen is shown while driving faster than 18 mph (29 km/h), screen goes away and system deactivates after 30 seconds.	PARALLEL PARK REDUCE SPEED TO SCAN FOR PARKING SPOT
Deactivation of the AdvanceTrac® system by the driver while the active park assist system is currently scanning for parking spots.	ACTIVE PARK ASSIST NOT AVAILABLE REFER TO OWNER GUIDE followed by a chime
The active park assist system is unavalible if the battery has been disconnected. Drive the vehicle straight above 25 km/h (16 mph) for a few minutes for the steering to center.
A vehicle attachment is detected by the reverse parking aid system, such as a trailer or bike rack. The attachments need to be electrically connected to the vehicle to prevent the active park assist from activating.	ACTIVE PARK ASSIST NOT AVAILABLE REFER TO OWNER GUIDE followed by a chime
Driver grabbing steering wheel while the active park assist system has control of the steering.	ACTIVE PARK ASSIST CANCELLED BY DRIVER followed by a chime
The driver opening the drivers door.
Deactivation of the AdvanceTrac® system by the driver while the active park assist system has control of the steering.	ACTIVE PARK ASSIST DEACTIVATED followed by a chime
An ABS activation or an AdvanceTrac® system activation occurs while the active park assist system has control of the steering.
Maximum number of moves is exceeded during any parking maneuver. The number is incremented each time the driver shifts gears, 9 is the maximum.

Component Description

Active Park Assist Sensors

The active park assist sensors are narrow beam ultrasonic sensors. The sensors continuously send out ultrasonic signals to detect an available parking space and communicate the information back to the IPMA . The sensors are active when the vehicle is moving regardless of whether the operator has pressed the active park assist switch. Only objects that reflect a sufficient amount of sound waves are detected by the active park assist sensors. The surface properties, size and composition of an object can affect the ability of the sensors to detect the object. Incorrect sensor alignment, dirt covered sensors, heavy rain and snow can cause objects not to be detected.

The operating temperature range for the active park assist sensors is -40°C (-40°F) to 85°C (176°F).

IPMA

The IPMA is the controlling module for the active park assist system. It processes the active park assist, parking aid sensor data, and camera data, provides the steering angle commands to the PSCM , ABS module, PCM and generates driver input requests through the centerstack infotainment display and audio system. The IPMA sets and stores Diagnostic Trouble Codes (DTCs) for the active park assist system. The IPMA communicates on the FD-CAN .

PMI is required if installing a new module.

Active Park Assist Switch

The active park assist switch is a momentary contact switch that enables and disables the active park assist system (parallel parking, perpendicular parking or parallel park out assist). The switch is integral to the ATCM located in the center console.