The PASSKey III vehicle theft deterrent system interfaces to a PASSKey III coded key to determine if a valid ignition key is attempting to start the vehicle's engine. If the key identification code is valid, the theft deterrent module sends a fuel enable signal to the Powertrain Control Module (PCM) to allow fuel delivery to the engine. If the key identification code is invalid, the theft deterrent module does not send a fuel enable signal to the PCM. This action causes the PCM to disable fuel delivery to the engine; thus the engine will crank but will not start.

The theft deterrent module can read the identification code inside the PASSKey III coded key in less than 0.25 seconds.

While the system is in standby mode, the parasitic current of the theft deterrent module is less than 0.5 amperes.

1. With key removed from ignition key cylinder, the system goes in standby mode. The SECURITY indicator stays off.
2. When turning the ignition switch to RUN with the proper PASSKey III coded key, the theft deterrent module reads and confirms the identification code in the key.
3. The theft deterrent module sends a fuel enable signal to the Powertrain Control Module (PCM). It also turns on the SECURITY indicator for two seconds.

1. When turning the ignition switch to RUN with a PASSKey III coded key that contains an invalid identification code, the theft deterrent module reads the identification code in the key and determines the code is illegitimate.
2. The theft deterrent module does not send a fuel enable signal to the PCM.
3. The theft deterrent module sets the tamper flag and runs a 10-minute lockout timer.
4. During this period, the theft deterrent module flashes the SECURITY indicator.
5. If the ignition key is turned to OFF/LOCK during the 10-minute lockout timer period, the system goes in standby mode. The lockout timer resumes where it left off upon turning the ignition switch back to RUN.
6. When the 10-minute lockout timer expires, the system goes in re-learn wait mode. The ignition switch must be cycled from RUN to OFF/LOCK back to RUN to in order to advance to the next mode.
7. Upon turning the ignition switch to RUN, the system re-enters tamper mode for a second time and another 10-minute lockout timer is run. When the 10-minute lockout timer expires, the system goes in re-learn wait mode. For a second time, the ignition switch must be cycled from RUN to OFF/LOCK back to RUN to in order to advance to the next mode.
8. Upon turning the ignition switch to RUN, the system re-enters tamper mode for a third time and another 10-minute lockout timer is run. When the 10-minute lockout timer expires, the system goes in re-learn wait mode. For a third time, the ignition switch must be cycled from RUN to OFF/LOCK back to RUN to in order to advance to the next mode.
9. Upon turning the ignition switch back to RUN, the system erases the previously stored identification codes and learns the new identification code in the PASSKey III coded key. The new identification code then becomes legitimate.
10. The theft deterrent module turns on the SECURITY indicator two seconds and sends a fuel enable signal to the PCM to enable fuel delivery to the engine. If the new identification code is from a valet key, the system will not store its value.
11. In order to store another identification code from another PASSKey III coded key, remove key from the ignition key cylinder, and within 10 seconds, insert a new key and turn the ignition switch to RUN.

1. When turning the ignition switch to RUN with a key that does not contain a PASSKey III identification code, the theft deterrent module enters the no coded key mode.
2. As long as the ignition switch remains in RUN during the no coded key mode, the SECURITY indicator flashes rapidly. Also, the theft deterrent module does not send a fuel enable signal to the PCM.
3. The theft deterrent module performs a key code read every 0.25 seconds during this mode. Note that if the system cannot read the identification code from the key, the system will not enter the 10-minute lockout timer. However, if an invalid key identification code is read, the system enters tamper mode.
4. To exit this mode, turn the ignition switch back to OFF/LOCK and start again with a different key.