Operation CHARM: Car repair manuals for everyone.

System Shutdown

When the key pellet value does not match the one stored in the Instrument Panel Clusters (IPC)'s memory, the IPC will not ground the Starter Enable Relay or send the Class 2 message to enable fuel for approximately three minutes.

If the ignition key is returned to "RUN" anytime during the three minute system Shutdown interval. the instrument Panel Cluster (IPC) will disregard the key pellet value until the three minute cycle is complete (even with the correct key).

After approximately three minutes, the Instrument Panel Cluster (IPC) will measure the resistance of the key pellet and compare it to the one stored in the IPC's memory. If the key pellets value matches, the IPC grounds the Starter Enable Relay, allowing the starter to operate. The IPC also sends a Class 2 message to the Powertrain Control Module (PCM). The PCM will then enable fuel. If the value of the key pellet still does not match, the IPC starts the three minute system shutdown over.

If the Instrument Panel Cluster (IPC) is unable to measure the resistance of the key pellet (due to damaged or missing pellet), the IPC does not start the three minutesystem shutdown (a readable key can he used right away to start the vehicle).