Parking Aid - System Operation and Component Description: Notes

System Operation

Pro Trailer Backup Assist™

System Diagram

Courtesy of FORD MOTOR COMPANY

Network Message Chart

PSCM Network Input Messages

Broadcast Message	Originating Module	Message Purpose
Gear lever position	TCM	Used for PTBA feature activation and video display.
Ignition status	BCM	Used to ensure the ignition state is appropriate for PTBA operation.
Trailer backup assist cancel request	APIM	Used to provide a cancel request from the APIM if it cannot support the PSCM display request.
Trailer backup assist enabled request	IPC	Used to enable the PSCM for PTBA operation for the trailer chosen by the user.
Trailer backup assist setup request	IPC	Request to setup up a new trailer.
Trailer backup assist status	IPMB	Used to provide the status of the PTBA system.
Trailer backup assist switch request	TRM	Used to provide the current PTBA control knob position and button status (pressed/not pressed).
Trailer ball to bumper distance	IPC	Indicates how far from the trailer ball is from the bumper.
Trailer setup	IPMB	Request to setup up a new trailer.
Trailer target to bumper distance	IPC	Indicates the target distance for the ball to bumper.
Vehicle speed	PCM	Used as an input to the PTBA controller in the PSCM.

IPMB Network Input Messages

Broadcast Message	Originating Module	Message Purpose
Message center display	IPC	Indicates what is displayed in the message center.
Message center feature configuration	IPC	Indicates the message center configuration.
Rear differential indicator request	TCCM	Used to indicate if there is a fault with the rear differential.
Rear differential lock indicator request	TCCM	Used to indicate if the rear differential has been locked.
Remote start status	BCM	Used to indicate if the vehicle is under remote start protocol.
Trailer angle offset direction status	IPC	Used to provide the trailer data for the current active trailer. Includes the trailer ID and all the trailer measurements stored in the IPC.
Trailer backup assist cancel request	APIM	Used to provide a cancel request from the APIM if it cannot support the PSCM display request.
Trailer backup assist enabled	PSCM	Used to request trailer angle detection in the IPMB.
Trailer backup assist enabled request	IPC	Request to setup up a new trailer.
Trailer backup assist setup status	IPC	Indicates the status of the trailer back up setup.
Trailer backup assist setup request	IPC	Request to setup up a new trailer.
Trailer backup assist text message request	PSCM	Used to provide PTBA centerstack infotainment display status to the IPMB.
Trailer ball to bumper distance	IPC	Indicates how far from the trailer ball is from the bumper.
Trailer lamp connected	TRM	Deactivates the system if a trailer is connected.
Trailer target to bumper distance	IPC	Indicates the target distance for the ball to bumper.
Vehicle lateral acceleration	RCM	Used to determine the current vehicle lateral acceleration.
Wheel speed data	ABS module	Used to confirm vehicle movement and calculate distance traveled during PTBA maneuvers.
Vehicle yaw rate	RCM	Used to determine the current vehicle yaw rate.

IPC Network Input Messages

Broadcast Message	Originating Module	Message Purpose
Gear lever position	PCM	Input used for the park requirement for trailer set up in the message center.
Steering wheel message center switch status	SCCM	Used for the message center navigation and trailer setup.
Trailer backup assist text message request	PSCM	Used to provide the trailer information message displays in the message center.
Trailer reverse message request	IPMB	Used to generate messages on the centerstack infotainment display.
Trailer setup	IPMB	Request to setup up a new trailer.
Trailer backup assist setup status	APIM	Indicates the status of the trailer back up setup.

TRM Network Input Messages

Broadcast Message	Originating Module	Message Purpose
Trailer backup assist text message	PSCM	Used to illuminate the status indicator in the PTBA control knob button when system is on.

BCM Network Input Messages

Broadcast Message	Originating Module	Message Purpose
Trailer assist lamp request	PSCM	Used to command the trailer assist lamp on and off for low ambient light operation.

PCM Module Network Input Messages

Broadcast Message	Originating Module	Message Purpose
Trailer backup assist enabled	PSCM	Used to limit the vehicle speed and throttle response when PTBA is in use.

APIM Network Input Messages

Broadcast Message	Originating Module	Message Purpose
Trailer backup assist text message request	PSCM	Used to generate messages on the centerstack infotainment display.
Trailer reverse message request	IPMB	Used to generate messages on the centerstack infotainment display.

Pro Trailer Backup Assist™

NOTE: The liftgate and doors must be fully closed for correct operation of the PTBA system.

NOTE: The trailer electrical connection status is irrelevant to the operation of the PTBA system.

NOTE: The rear audible parking aid system is disabled automatically while the PTBA system is active.

NOTE: The transmission needs to be in park (P) to input the needed measurements into the IPC message center.

In order to utilize the PTBA system, a compatible conventional trailer equipped with a correctly positioned trailer target sticker needs to be connected to the vehicle. Some measurements and trailer specifications have to be entered through the IPC message center trailer towing tab, using the LH upper steering wheel switch. The trailer information is stored in the IPC for easy recall and the IPC can store up to a maximum of 10 different conventional trailers. Refer to the Owner's Literature (Pro Trailer Backup Assist Quick Start Guide) to find the detailed steps and instructions required to properly position the vehicle and trailer in order to setup, calibrate and operate the PTBA system. For best results, it is not recommended to calibrate the system in low ambient light conditions. Refer to the Owner's Literature for tips to resolve warnings or difficulties that may occur during setup.

NOTE: The PTBA control knob inputs to the TRM.

NOTE: The TRM is the governing module for the PTBA status indicator on the PTBA control knob.

After the PTBA system is setup, the steering system receives a hitch angle from the camera and the driver can adjust the curvature of the trailer path using the PTBA control knob located on the instrument panel. The PTBA control knob includes a button to enable and disable the system, a knob to control the direction of the trailer while reversing and a status indicator on the button. When the PTBA control knob button is pressed and a stored trailer is selected, the IPC message center and the centerstack infotainment display prompts the driver to shift to REVERSE (R) to activate the system. When the system is in use, releasing the PTBA control knob allows the knob to return to center or zero curvature and the vehicle follows the trailer path. Pressing and releasing the PTBA control knob button or turning the steering wheel at any time the system is active, disables the PTBA system. If the system is disabled by the operator after the system starts to control the steering, the centerstack infotainment display displays a PTBA canceled message followed by a warning chime.

The PTBA system keeps the trailer angle and speed within reasonable operating limits enabling the driver to control the path of the trailer. Vehicle speed is always limited to below 10 km/h (6 mph) when the PTBA system is active and the feature deactivates if 10 km/h (6 mph) is exceeded. Vehicle brakes may be automatically applied and engine torque may be automatically reduced to limit speed. The target speed limit varies depending on operating conditions but can be as low as 3 km/h (2 mph).

Several modules communicate with each other to control the PTBA system functions. The TRM reads the PTBA control knob and button analog signals and sends them on the MS-CAN through the GWM to the PSCM on the HS-CAN2. The rear parking aid camera captures the trailer target sticker image on the trailer and sends the data to the IPMB over two video signal circuits. The IPMB reads the video signal from the rear parking aid camera and determines the tracking status and trailer angle based on the entered dimensions if the trailer target sticker is detected. The trailer target sticker data is then sent from the IPMB to the PSCM over the HS-CAN2. The PSCM uses all the data it receives from each interfacing module to control overall PTBA system operation. The following are outputs of the PTBA controller software in the PSCM:

Request for warning or instructions to the driver to be displayed in the IPC and centerstack infotainment display.
Steering wheel position to achieve the desired trailer curvature (indicated by the knob position).
Braking and powertrain speed limiting requests.
Activation and deactivation of the PTBA system.

Certain conditions can cause the PTBA to incorrectly align the vehicle and trailer (not backup straight):

PTBA control knob concern.
A spare tire installed on the vehicle or trailer.
One of the tires on the vehicle or trailer has significantly more or less treadwear than the other tires.
One of the tires on the vehicle or trailer is deflated or over inflated.
Different tire sizes are used on the vehicle or trailer.
The drawbar connection to the hitch receiver is inadequate.
Trailer suspension concern.
The rear parking aid camera, or liftgate.
The trailer frame or tongue is damaged.
The ground is irregular.

It is possible to compensate for the trailer drifting to the right or left by slowly turning the PTBA control knob until the trailer is following your desired path and then holding the knob in that position. Fixing the cause of the concern and as needed recalibrating the system is recommended for straight backing.

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

PTBA Image Display

On vehicles equipped with the 360 degree view camera system, when the ignition is ON, the PTBA control knob button is in the on position and reverse gear is selected, the rear parking aid camera views are shown on the FDIM. In the Rear PTBA 360 + Rear Normal view, the rear park aid camera view image in the PTBA 360 degree view is replaced with a trailer graphic. The Rear Normal view contains an icon representing a trailer attached to a truck on the right side of the display. The Rear PTBA 360 + Rear Normal view is shown first. Subsequent presses of the camera selection switch allow the driver to cycle through the rear parking aid camera views in the following order:

View order	View name	Description
1	Rear PTBA 360 + Rear Normal	Contains the normal rear parking aid camera view, shown next to a PTBA 360 degree camera view.
2	Rear Normal	Provides an image of what is directly behind the vehicle.

On vehicles equipped with the rear only parking aid camera system, when the ignition is ON, the PTBA control knob button is in the on position and reverse gear is selected, the rear PTBA camera view is shown on the FCDIM. The rear PTBA camera view contains an icon representing a trailer attached to a truck on the right side of the display.

For additional information on the centerstack infotainment display, Refer to: Parking Aid - System Operation and Component Description .