General Information

When a key is inserted in the ignition, contacts that are located in the steering column (ignition) lock cylinder contact a resistor pellet located in the ignition key. The theft deterrent module measures the resistance of the key pellet. The module compares this value to a value stored in memory. The theft deterrent module then performs one of the following functions:
^ If the values match, the theft deterrent module performs the following system enable functions:
^ The module provides a ground for the theft deterrent relay at terminal A4 (CKT 625, YEL/BLK). The ground enables the starter to operate.
^ The module sends a proper pulse width modulated (PWM) signal to the PCM. The signal travels via CKT 229 (DK BLU), terminal A3. When the PCM receives this input, the PCM enables the fuel delivery system.
^ If the values do not match, the theft deterrent module performs the following system disable functions for approximately 3 minutes:
^ No ground is provided to the theft deterrent relay. The starter is disabled.
^ No command is given to the PCM in order to enable the fuel delivery system.

If you turn the ignition switch to the RUN position anytime during the system disable interval, the theft deterrent module disregards the key pellet value until the 3 minute system disable interval is complete. This action occurs even if you use the correct key pellet value.

After approximately 3 minutes, the theft deterrent module performs the following actions:
^ The module measures the key pellet resistance.
^ The module compares the key pellet resistance to a value stored in memory.

If the values match, the theft deterrent module performs the system enable function. If the values do not match, the module performs the system disable functions again.

If the theft deterrent module is unable to measure the key pellet resistance due to a damaged or a missing pellet, the module does not perform the system enable or system disable functions. No 3 minute interval is performed. A measurable key with the correct resistance value can be used in order to start the vehicle.