General Description

Personnel Automotive Security SYS (Pass-Key (R) III) Operation

When a ignition key is inserted into the ignition cylinder, wire coils surrounding the ignition cylinder energizes a transponder pellet located within the plastic portion of the ignition key. The energized transponder transmits a unique value by radio frequency back to the coils which are part of the PASS-Key(R) III module. When the PASS-Key(R) III module detects ignition voltage (ignition switch in RUN or START) at terminal E (CKT 1020, PNK) the module measures the transponder pellet value being received by the coils. The PASS-Key(R) III module then validates this value and performs one of the following functions:
^ If the value is valid, the PASS-Key(R) III module performs the following (system enable) functions:
- Sends a class 2 system enable message (unique password) to the PCM, the PCM enables the fuel system and provides a ground for the starter relays, thus enabling the engine to start.
^ If the value is invalid, the PASS-Key(R) III module performs the following (system disable) functions for approximately three minutes:
- Sends a class 2 system disable message (unique password) to the PCM, the PCM does not enable the fuel system or provide a ground for the starter enable relays, for approximately 3 minutes.

This password is unique for each PASS-Key(R) III module, thus preventing a thief from swapping the PASS-Key(R) III module or the PCM in order to start the vehicle. If the PCM receives an invalid password indicating a swapped PASS-Key(R) III module or PCM, the fuel or starter systems are not enabled.

If the ignition switch is turned to the RUN position anytime during the system disable interval, the PASS-Key(R) III module disregards the transponder value until the three minute system disable interval is complete (even if an ignition key with a valid transponder value is used).

When the system disable interval expires the PASS-Key(R) III module measures the ignition key transponder value when the ignition switch is turned to the RUN position.

If the PASS-Key(R) III module is unable to measure the ignition key transponder value (due to a damaged or missing pellet), the PASS-Key(R) III module performs the system disable functions, but does not activate the 3 minute system disable interval. An ignition key with a valid transponder value can be used to start the vehicle.