Operation CHARM: Car repair manuals for everyone.
Home >> Ford Truck >> 2012 >> E 250 V8-5.4L >> Repair and Diagnosis >> Accessories and Optional Equipment >> Antitheft and Alarm Systems >> Testing and Inspection >> Initial Inspection and Diagnostic Overview >> Principles of Operation

Principles of Operation




Anti-Theft

Principles of Operation

NOTE: Replacement of the Passive Anti-Theft System (PATS) transceiver does not require the PATS (Passive Anti-Theft System) keys to be programmed into the Instrument Panel Cluster (IPC) again.

NOTE: Make sure any aftermarket remote start systems have been removed from the vehicle before any PATS (Passive Anti-Theft System) -related no-start concerns are investigated.

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

Anti-Theft Indicator

PATS (Passive Anti-Theft System) uses a visual anti-theft indicator located in the IPC (Instrument Panel Cluster). The anti-theft indicator proves out for 3 seconds when the ignition key is in the ON or START position. If there is a PATS (Passive Anti-Theft System) concern, the anti-theft indicator either flashes rapidly or glows steadily when the ignition key is turned to the ON or START position. PATS (Passive Anti-Theft System) also flashes the anti-theft indicator every 2 seconds when the ignition key is in the OFF position to act as a visual theft deterrent. for information on the anti-theft indicator.

PATS (Passive Anti-Theft System) is active only for a few seconds when the vehicle is starting. It is not a PATS (Passive Anti-Theft System) concern if the vehicle stalls after it has been running for a minimum of 3 seconds. PATS (Passive Anti-Theft System) cannot disable a running vehicle.

A PATS (Passive Anti-Theft System) no-start can involve a vehicle no-start due to either the fuel injectors or the starter not operating (or both). If the PATS (Passive Anti-Theft System) anti-theft indicator does not prove out and one (or both) of the previous conditions are present, it can be due to a PATS (Passive Anti-Theft System) concern. If the anti-theft indicator proves out, and the vehicle does not start, it is probably not a PATS (Passive Anti-Theft System) concern. Refer to Computers and Control Systems Information. If the anti-theft indicator does not illuminate at all, it can be an IPC (Instrument Panel Cluster) concern. GO to Symptom Chart. Symptom Related Diagnostic Procedures A low battery voltage condition can cause the PATS (Passive Anti-Theft System) to allow starter operation, but can keep the fuel injectors from operating.

Passive Anti-Theft System (PATS) Keys

NOTE: A minimum of 2 keys must be programmed into the IPC (Instrument Panel Cluster) before the vehicle starts.

PATS (Passive Anti-Theft System) uses a special ignition key that is larger than a conventional ignition key. It contains a permanently-installed electronic device called a transponder. Each transponder contains a unique encrypted identification code which is one of a very large number of combinations. The addition of this transponder to the key makes it an "encoded" key. The PATS (Passive Anti-Theft System) key does not require batteries and should last the lifetime of the vehicle. Each PATS (Passive Anti-Theft System) key must be programmed into the IPC (Instrument Panel Cluster) before it can be used to start the vehicle. A maximum of 8 PATS (Passive Anti-Theft System) keys can be programmed to start the vehicle. There are special procedures described that must be carried out if a new PATS (Passive Anti-Theft System) key is necessary. Refer to Key Programming Using Diagnostic Equipment Passive Anti-Theft System (PATS) Key Programming Using Diagnostic Equipment or Key Programming Using Two Programmed Keys Passive Anti-Theft System (PATS) Key Programming Using Two Programmed Keys.

Passive Anti-Theft System (PATS) Transceiver

The PATS (Passive Anti-Theft System) transceiver is located under the steering column shroud and communicates with the encoded ignition key. During each vehicle start sequence, the PATS (Passive Anti-Theft System) transceiver reads the encoded ignition key identification code and sends data to the IPC (Instrument Panel Cluster). The IPC (Instrument Panel Cluster) validates the code, and if it is the correct code, sends a message to the PCM to ground the starter relay solenoid coil and allow the fuel injectors to operate.

Passive Anti-Theft System (PATS) Operation

The PATS (Passive Anti-Theft System) function is controlled by the IPC (Instrument Panel Cluster). With this type of PATS (Passive Anti-Theft System), there are parameters that need to be reset if either the IPC (Instrument Panel Cluster) or the PCM (or both) are replaced. Refer to Passive Anti-Theft System (PATS) Parameter Reset Passive Anti-Theft System (PATS) Passive Anti-Theft System (PATS) Parameter Reset.

When the PATS (Passive Anti-Theft System) key is turned to the ON or START position, the IPC (Instrument Panel Cluster) initiates the key interrogation sequence by sending a voltage signal to the PATS (Passive Anti-Theft System) transceiver. The transceiver then uses its antenna to bounce a signal off the transponder in the PATS (Passive Anti-Theft System) key. This process "reads" the PATS (Passive Anti-Theft System) key identification code and sends the key identification code back to the IPC (Instrument Panel Cluster), which interprets it and determines if it matches one of the stored key codes. If it does match one of the stored key codes, the IPC (Instrument Panel Cluster) sends a message to the PCM to ground the starter relay solenoid coil and allow the fuel injectors to operate. If it does not match one of the stored key codes, or it is only a partial key read or no key read, the IPC (Instrument Panel Cluster) sends a message to the PCM to not ground the starter relay solenoid coil and not allow fuel injector operation. The anti-theft indicator in the IPC (Instrument Panel Cluster) flashes (or may glow steadily) and the IPC (Instrument Panel Cluster) stores one or more DTCs.

All elements of PATS (Passive Anti-Theft System) must be functional before the vehicle starts. If any of the components are not working correctly, the vehicle cannot start.

If the IPC (Instrument Panel Cluster) must be replaced for any reason (PATS (Passive Anti-Theft System) or IPC (Instrument Panel Cluster) concerns), the PATS (Passive Anti-Theft System) keys must also be programmed into the new IPC (Instrument Panel Cluster). Refer to Key Programming Using Diagnostic Equipment Passive Anti-Theft System (PATS) Key Programming Using Diagnostic Equipment.

PATS (Passive Anti-Theft System) disables the vehicle from starting if there is:

- a damaged PATS (Passive Anti-Theft System) key.

- a non-programmed PATS (Passive Anti-Theft System) key.

- a non-PATS (Passive Anti-Theft System) key (key has no electronics).

- damaged wiring.

- a damaged transceiver.

- a damaged IPC (Instrument Panel Cluster).

- a damaged PCM.

Passive Anti-Theft System (PATS) PIDs

Monitoring the PATS (Passive Anti-Theft System) PIDs in the IPC (Instrument Panel Cluster) can be very useful in determining which diagnostic steps to follow. Viewing the MASTERKEY PID (verifies if the key is programmed) (with both keys) determines if the key is a programmed key and proves-out the transceiver, circuitry and the IPC (Instrument Panel Cluster). A master key is any key that is programmed into the IPC (Instrument Panel Cluster). Viewing the MIN_KEYS PID (minimum number of keys) (this PID does not change) indicates the minimum number of keys that must be programmed into the IPC (Instrument Panel Cluster) in order for the vehicle to start. There must be at least 2 keys programmed into the IPC (Instrument Panel Cluster) in this type of PATS (Passive Anti-Theft System) before the vehicle starts. Viewing the N_KEYCODE PID (number of keys programmed) determines if the minimum number of keys has been programmed into the IPC (Instrument Panel Cluster). If the N_KEYCODE PID reads 0 or 1, additional key(s) needs to be programmed into the IPC (Instrument Panel Cluster) in order to meet the minimum of 2 keys. If the N_KEYCODE PID reads 0 or 1, and the MASTERKEY PID reads Not Present, that particular key must be programmed into the IPC (Instrument Panel Cluster). If the N_KEYCODE PID reads 1, and the MASTERKEY PID reads Present, that particular key is already programmed into the IPC (Instrument Panel Cluster). The SPAREKEY (spare key) PID is defaulted to ENABLE.

When the parameters in the IPC (Instrument Panel Cluster) are reset, it clears (erases) the PCM ID from the IPC (Instrument Panel Cluster). A PCM parameter reset causes the PCM to send a PCM ID to the IPC (Instrument Panel Cluster) that is necessary for the system to operate. Make sure to cycle the key at least once, then turn the key ON and make an attempt to start the vehicle for 3-5 seconds before attempting more procedures. If only a PCM parameter reset occurs, the ID stored in the IPC (Instrument Panel Cluster) does not match the ID being sent by the PCM, and can cause a PATS (Passive Anti-Theft System) -related no-start. Carry out the parameter reset, and do not cycle the key until after the parameter reset selection has been highlighted, and the on-screen instructions have been followed. The IDS (Integrated Diagnostic System) then resets the parameters in both the IPC (Instrument Panel Cluster) and the PCM at the same time. Passive Anti-Theft System (PATS) Passive Anti-Theft System (PATS) Parameter Reset

If the PCM_ID reads Stored, the IPC (Instrument Panel Cluster) has a PCM ID stored. If it reads Not Stored, a parameter reset may resolve this issue. If the PCM_VFY PID (PCM verify) reads No, the N_KEYCODE PID reads 2 or more and the MASTERKEY PID reads Present, the IPC (Instrument Panel Cluster), and the PCM need to have their parameters reset. Refer to Passive Anti-Theft System (PATS) Parameter Reset Passive Anti-Theft System (PATS) Passive Anti-Theft System (PATS) Parameter Reset.

If the PCM_VFY PID reads No, the N_KEYCODE PID reads 1 and the MASTERKEY PID reads Present, or if the N_KEYCODE PID reads 0 and the MASTERKEY PID reads Not Present, a minimum of 2 keys need to be programmed into the IPC (Instrument Panel Cluster). Refer to Key Programming Using Diagnostic Equipment Passive Anti-Theft System (PATS) Key Programming Using Diagnostic Equipment.

The SPAREKEY PID in the IPC (Instrument Panel Cluster) is defaulted to ENABLE. With the SPAREKEY PID displaying ENABLE, the IPC (Instrument Panel Cluster) accepts more than 2 keys (up to a maximum of 8) being programmed into the IPC (Instrument Panel Cluster) using the Key Programming Using Two Programmed Keys Passive Anti-Theft System (PATS) Key Programming Using Two Programmed Keys procedure. The SPAREKEY PID can be toggled to DISABLE if the customer wants to disable the customer spare key programming function. To enable or disable the spare key feature, refer to Key Programming Switch State Control Passive Anti-Theft System (PATS) Key Programming Switch State Control. This switch state control does not affect the Key Programming Using Diagnostic Equipment Passive Anti-Theft System (PATS) Key Programming Using Diagnostic Equipment procedure.

In summary, for the PATS (Passive Anti-Theft System) PIDs and their correct state in order for the vehicle to start:

- N_KEYCODE must read 2 or more

- MASTERKEY must read Present

- PCM_ID must read Stored

- PCM_VFY must read Yes

Unlimited Key Mode

PATS (Passive Anti-Theft System) contains a feature named unlimited key mode that has an UNL_KEY_MODE PID (unlimited key mode). This feature allows a customer to program more than 8 keys to their vehicle if they request it. Each vehicle in unlimited key mode is set up with a special unlimited transponder security key code. This allows all the customer vehicles to share the same mechanically cut keys, but no other keys from outside can be used to operate the vehicles. For an individual customer, any randomly selected security key that has been previously mechanically cut and electronically programmed to the vehicle is acceptable. Refer to Spare Key Programming - Unlimited Key Mode Passive Anti-Theft System (PATS) Spare Key Programming - Unlimited Key Mode.
pro multis · About Operation CHARM