PASS-Key® II is a registered trademark of the Delco Electronics Corporation.
When a key is inserted in the ignition, the contacts located in the ignition cylinder contact a resistor pellet located in the key. The instrument cluster (IPC) measures the resistance of the key pellet. The IPC then compares this value to a value stored in the IPC's memory. The IPC then performs one of the following functions:
| • | If the values match, the IPC performs the following (system enable) functions: |
| - | Provides a ground for the starter enable relay, enabling the starter to operate. |
| - | Sends a class 2 message to the PCM. The PCM then enables the fuel system to operate. |
| • | If the values do not match, the IPC performs the following (system disable) functions for approximately 3 minutes: |
| - | No ground is provided to the starter enable relay, disabling the starter. |
| - | No system enable class 2 message is sent to the PCM. The PCM does not enable the fuel system for approximately 3 minutes. |
If the ignition switch is turned to the RUN position anytime during the system disable interval, the IPC disregards the key pellet value until the 3 minute system disable interval is complete (even if the correct key pellet value was used).
After approximately 3 minutes, the IPC measures the key pellet resistance. The IPC compares this value to the one stored in the IPC's memory. If the values match, the IPC performs the system enable function (see above). If the values do not match, the IPC performs the system disable functions again (see above).
If the IPC is unable to measure the key pellet resistance (due to a damaged or missing pellet), the IPC does not perform the system disable functions. Use a readable key with the correct resistance value in order to start the vehicle.
Ignition Key
The ignition key for the vehicles equipped with the PASS-Key® II system consists of a typical square ignition key blank and a resistor pellet. The PASS-Key® II ignition key has the same mechanical key cuts of a non PASS-Key® II ignition key. Do not service the key blank and the resistor pellet separately. There are 15 different ignition key assemblies, each with a different key pellet resistance value.
Steering Column Lock Cylinder
The steering column lock cylinder used with the PASS-Key® II system contains a set of electrical terminals used in order to contact the resistor in the ignition key. The wire routing for the contacts inside the steering column is very critical. When servicing the lock cylinder, maintain proper wire routing. When replacing a steering column lock cylinder, make new keys which match the PASS-Key® II key code of the PASS-Key® II system and the mechanical cut of the new lock cylinder.
Instrument Cluster (IPC)
The instrument cluster (IPC) contains the software for controlling the PASS-Key® II system. The IPC monitors the following components:
| • | The key-in-ignition input CKT 80 (LT GRN) |
| • | The ignition key resistor input CKT 1073 (WHT/BLK) |
The IPC controls the starter enable output CKT 625 (YEL/BLK). The IPC also sends a fuel enable message to the powertrain control module (PCM) via the class 2 serial data line.
Key-In-Ignition Input
The key-in-ignition input CKT 80 (LT GRN) is used in order to wake up the instrument cluster (IPC) when a key is inserted into the steering column lock cylinder (ignition switch). When the IPC wakes up, the IPC measures the key pellet resistance value on the ignition key resistor input CKT 1073 (WHT/BLK).
Ignition Key Resistor Input
The ignition key resistor input CKT 1073 (WHT/BLK) is used by the instrument cluster (IPC) in order to measure the key pellet resistance.
Starter Enable Output
The starter enable output CKT 625 (YEL/BLK) is used by the instrument cluster (IPC) in order to control the starter enable relay.
Theft Deterrent Relay
The starter enable relay is controlled by the instrument cluster (IPC) via the starter enable output CKT 625 (YEL/BLK). If the IPC measures the correct key pellet resistance value, the IPC switches the starter enable output CKT 625 (YEL/BLK) to ground. The relay is energized if the ignition switch is in the START position and the gear selector is in the PARK or NEUTRAL positions.
Powertrain Control Module (PCM)
The powertrain control module (PCM) monitors the class 2 serial data line for the fuel enable message from the instrument cluster (IPC). If the fuel enable message is not present, the PCM does not enable the fuel system during the engine crank. If the message is present, the PCM enables the fuel system. This condition allows the engine to start during the engine crank.
