System Operation: Pats

WARNING: This page is about a different car, the 2017 Ford F-550 Super Duty, 2017 Ford F-450 Super Duty, 2017 Ford F-350 Super Duty, and 2017 Ford F-250 Super Duty. However, it is still accessible from the selected car via links, so may be relevant.

The PATS function is controlled by the BCM and the PCM.

When the START/STOP button is pressed, a signal is sent to the BCM. When the BCM detects the START/STOP button is pressed, it begins the key initialization sequence by activating the PATS center antenna, the PATS rear antenna and both exterior door handle keyless entry antennas. Each antenna transmits a low frequency signal with an approximate range of 1 m (3 ft). The passive key activates if it is within range of the antennas. The BCM is able to determine the passive key location (inside or outside the vehicle) based on the input from the antennas.

When the passive key activates, it sends the PATS identification code to the RTM via a high frequency signal. The RTM interprets the high frequency signal from the passive key and sends the information to the BCM over the LIN-based circuit.

If a valid programmed passive key is detected inside the vehicle, the BCM transitions the ignition out of off.

When the ignition transitions out of off and the modules initialize, the PCM sends a challenge request to the BCM. The BCM replies and if the correct identification is received, the PATS disables and allows the vehicle to start. If the PATS prevents the vehicle from starting, a DTC sets in one of the modules.

The PATS and the RKE system share operation of several components including the passive keys, the BCM and the RTM.

If there is a concern with any of these components, the PATS and the RKE system are both affected.

In the event of a no start, place a programmed passive key in the backup location to allow the vehicle to start. The PATS center antenna activates the passive key when the START/STOP button is pressed in the event the batteries are depleted within the passive key.

NOTE: If available as a selection on the scan tool, the passive start feature is a programmable parameter and can be enabled/disabled. If the feature is disabled, the features to passively enter and start the vehicle are inoperative. To start the vehicle, the passive key must be placed in the backup starting location.

The BCM controls the ignition modes and, in conjunction with the PCM, control the PATS.

For information on ignition states, Refer to: Steering Wheel and Column Electrical Components - System Operation and Component Description .

PATS Parameter Identifications (PIDs)

In conjunction with Diagnostic Trouble Codes (DTCs), the PATS Parameter Identifications (PIDs) are a useful tool when diagnosing PATS concerns.

BCM PID Chart

Acronym	Name	Description
KEYS_PROGMD	Number of ignition key codes supported	Displays the number of keys currently programmed into the BCM.
MIN_KEYS_RQD	Minimum number of keys required	Minimum number of programmed keys required. This PID always reads 2.

PCM PID Chart

Acronym	Name	Description
PATSENABL	Vehicle enable status	Indicates if PATS allows the vehicle to be driven. Must read enabled for the vehicle to be driven.