Principles of Operation

WARNING: This page is about a different car, the 2011 Mercury Milan, 2011 Lincoln MKZ, and 2011 Ford Fusion. However, it is still accessible from the selected car via links, so may be relevant.

NOTE: The Smart Junction Box (SJB) is also known as the Generic Electronic Module (GEM).

The parking aid sensors detect objects approximately 152 cm (60 in) from the rear of the vehicle, 50 cm (1.6 ft) from the rear side of the vehicle, and 30 cm (12 in) above the ground. The Parking Aid Module (PAM) calculates the distance to an object within the 170 degree semicircular area around the rear of the vehicle. A variable warning tone is generated from a parking aid speaker. The parking aid speaker increases its warning tone rate as the vehicle gets closer to an obstacle. When an object is detected within 25 cm (10 in) of the sensors, the warning tone becomes continuous.

The parking aid speaker has a dual function for vehicles equipped with the parking aid system and cross traffic alert system. The parking aid speaker will emit an audible warning tone to notify the driver of impeding traffic from the side of the vehicle when backing out of parking spaces. Refer to WARNING SYSTEM - SIDE VISION & REAR VISION -- FUSION, MILAN & MKZ article for cross traffic alert information.

The parking aid system is enabled when the ignition switch is in the RUN position and the REVERSE (R) gear is selected. The parking aid system is disabled if a fault is detected in 1 of the 3 sensors, the parking aid speaker, or the PAM. This is indicated by a warning and the message center will display the message "CHECK PARK AID".

The PAM is on the Medium Speed Controller Area Network (MS-CAN) and can be diagnosed with a scan tool. The PAM communicates with the scan tool, the Audio Control Module (ACM), the SOD-L, the SOD-R and the Instrument Panel Cluster (IPC). The following chart describes network messages used by the PAM:

NOTE: Both the MS-CAN and the High Speed Controller Area Network (HS-CAN) are used for intermodule communication. A gateway message is transferred from one network to another network through the IPC. Refer to MODULE COMMUNICATIONS NETWORK -- FUSION, MILAN & MKZ article for network communication information.

PAM NETWORK COMMUNICATION MESSAGES

Broadcast Message	Originating Module	Network Type	Receiving Module
Ignition switch position	IPC	MS-CAN	PAM
Parking aid sounder volume cutback request	PAM	MS-CAN	ACM
Parking aid enabled status	IPC	MS-CAN	PAM
Parking aid system status	PAM	MS-CAN	IPC
Transmission selector (PRNDL) range (gateway)	IPC	MS-CAN	PAM
Side obstacle detection cross traffic alert	SOD-L and SOD-R	MS-CAN	PAM
Vehicle speed (gateway)	IPC	MS-CAN	PAM