Passive Anti-Theft System (PATS) PIDs

Monitoring the PATS PIDs can be very useful in determining which diagnostic steps to follow. Viewing the MASTERKEY (master key) PID with both keys determines if the key is a programmed key and can also be used to prove out the transceiver, circuitry and the IPC. A master key is a key that is programmed into the IPC. Viewing the MIN_KEYS (minimum number of keys) PID (this PID does not change) determines the minimum number of keys that must be programmed into the IPC. There must be at least 2 keys programmed into the IPC in this type of PATS before the vehicle starts. Viewing the N_KEYCODE (number of keys programmed) PID determines if the minimum number of keys have been programmed into the IPC. If the N_KEYCODE PID reads 0 or 1, additional key(s) need to be programmed into the IPC 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. If the N_KEYCODE PID reads 1, and the MASTERKEY PID reads Present, that particular key is already programmed into the IPC. In this particular case, there are not enough keys programmed (a minimum of 2 are needed before the vehicle starts) into the IPC and at least 1 more key needs to be programmed before the vehicle starts. Refer to INTEGRATED KEYHEAD TRANSMITTER (IKT) KEY PROGRAMMING USING DIAGNOSTIC EQUIPMENT  in this service information.

Also, if the unlimited key mode has been enabled, the N_KEYCODE PID always reads 2, after the first 2 keys are programmed into the IPC, regardless of how many additional keys are added.

When the parameters are reset, it clears (erases) the TCM ID from the IPC. A parameter reset causes the TCM to send a TCM ID to the IPC 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 TCM parameter reset occurs, the ID stored in the IPC does not match the ID being sent by the TCM, and can cause a PATS-related no-start. Carry out a PATS parameter reset, then turn the key ON and make an attempt to start the vehicle for 3-5 seconds before attempting more procedures.

If the PCM_ID (TCM id status) PID reads Stored, the IPC has a TCM ID stored. If it reads Not Stored, a parameter reset may resolve this concern. If the PATSENABL (vehicle enable status) PID reads Disabled, and the N_KEYCODE PID reads 2 or more and the MASTERKEY PID reads Present, the IPC and the TCM need to have their parameters reset. Refer to PASSIVE ANTI-THEFT SYSTEM (PATS) PARAMETER RESET  in this service information.

If the PATSENABL PID reads Disabled, and 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. Refer to INTEGRATED KEYHEAD TRANSMITTER (IKT) KEY PROGRAMMING USING DIAGNOSTIC EQUIPMENT  in this service information.

If the MASTERKEY PID continues to read Not Present after programming, this may indicate a defective key. The SPAREKEY PID is defaulted to ENABLE. With the SPAREKEY PID displaying ENABLE, the IPC accepts more than 2 keys (up to a maximum of 8) being programmed into the IPC using Key Programming Using Two Programmed Keys in this service information. It can be toggled to DISABLE if the customer wants to disable the customer spare key programming function. Refer to KEY PROGRAMMING SWITCH STATE CONTROL  in this service information. This switch state control does not affect the Integrated Keyhead Transmitter (IKT) Key Programming Using Diagnostic Equipment procedure.

In summary, in order for the vehicle to start, the PATS PIDs and their correct state they must be in are as following: