General Information

When a key is inserted in the ignition, 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 and 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 three minutes:
- No ground 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 three 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 three minute system disable interval is complete (even if the correct key pellet value was used).

After approximately three minutes, the IPC measures the key pellet resistance and compares it 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 system disable functions (a readable key with the correct resistance value can be used to start the vehicle).