Passive Anti-Theft System (PATS) PIDs
Monitoring the PATS PIDs can be very useful in determining which diagnostic steps to follow. Viewing the MASTERKEY (verifies if the key is programmed) 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 IC . A master key is any key that is programmed into the IC . 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 IC . There must be at least 2 keys programmed into the IC 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 IC . If the N_KEYCODE PID reads 0 or 1, additional key(s) need to be programmed into the IC 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 IC . If the N_KEYCODE PID reads 1, and the MASTERKEY PID reads Present, that particular key is already programmed into the IC . If the IC was replaced, the parameters in the IC and the parameters in the PCM need to be reset.
When the parameters in the IC are reset, it clears (erases) the PCM ID from the IC . A PCM parameter reset causes the PCM to send a PCM ID to the IC 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 IC will not match the ID being sent by the PCM, and can cause a PATS -related no-start.
If the PCM_ID (PCM id status) PID reads Stored, the IC has a PCM ID stored. If it reads Not Stored, a parameter reset of the PCM may resolve this issue. If the PCM_VFY (PCM verify status) PID reads No, and the N_KEYCODE reads 2 or more and the MASTERKEY reads Present, the IC and the PCM need to have their parameters reset. Refer to PASSIVE ANTI-THEFT SYSTEM (PATS) PARAMETER RESET . In this particular scenario, the PATSENABL (vehicle enable status) PID reads Disabled.
If the PCM_VFY PID reads NO, 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 IC . Refer to INTEGRATED KEYHEAD TRANSMITTER (IKT) KEY PROGRAMMING USING DIAGNOSTIC EQUIPMENT .
If the MASTERKEY PID continues to read Not Present after programming, this may indicate a defective key.
The SPAREKEY (spare key) PID is defaulted to ENABLE. With the SPAREKEY PID displaying ENABLE, the IC accepts more than 2 keys (up to a maximum of 8) being programmed into the IC using Key Programming Using Two Programmed Keys. 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 . This switch state control does not affect the Key Programming Using Diagnostic Equipment procedure.
Also, if the unlimited key mode has been enabled, the N_KEYCODE PID reads 2 after the first 2 keys have been programmed into the IC . If more than 2 keys are programmed, the N_KEYCODE PID reads 2.
In summary, for the PATS 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
- PATSENABL must read Enabled