Principles of Operation

WARNING: This page is about a different car, the 2009 Mercury Milan, 2009 Lincoln MKZ, and 2009 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 1.6 m (5.3 ft) from the rear of the vehicle, 50 cm (1.6 ft) from the rear side of the vehicle, and 16 cm (6 in) above the ground. The parking aid module (PAM) calculates the distance to an object within the 170 degree semicircular azimuth area around the rear of the vehicle. A variable warning tone is generated from a parking aid speaker attached to the PAM. 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 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 4 sensors, the parking aid speaker, or the PAM. This is indicated by the parking aid disabled warning in the message center.

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 SJB, the audio control module (ACM) and the instrument cluster (IC). The following chart describes network messages used by the parking aid module:

NOTE: Both the Medium Speed Controller Area Network (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 Instrument Cluster (IC). Refer to MODULE COMMUNICATIONS NETWORK article for network communication information.

PARKING AID MODULE (PAM) NETWORK COMMUNICATION MESSAGES

Broadcast Message	Originating Module	Network Type	Receiving Module
Ignition switch position	IC	MS-CAN	PAM
Parking air audio volume cutback command	PAM	MS-CAN	ACM
Parking aid enabled status	IC	MS-CAN	PAM
Parking aid system status	PAM	MS-CAN	IC
Transmission selector (PRNDL) range	Transmission Control Module (TCM)	HS-CAN	IC
Transmission selector (PRNDL) range (gateway)	IC	MS-CAN	PAM
Vehicle speed	PCM	HS-CAN	IC
Vehicle speed (gateway)	IC	MS-CAN	PAM