Circuit Operation

The PASS-Key II system prevents the engine from starting if the proper resistance is not sensed from the ignition key. Only one of the 15 resistance values available works with each PASS-Key II module.

The PASS-Key II module controls the starter enable relay and the Powertrain Control Module (PCM) fuel enable input If the PASS-Key II module does not send the proper Pulse Width Modulated (PWM) signal to the PCM fuel enable input, the PCM does not allow fuel to be provided to the engine.

Resistor sensing contacts are located in the Ignition Key Lock Cylinder. These contact the Key Resistor Pellet on the key when it is inserted. Rotating the lock applies ignition voltage to the PASS-Key II module and pellet resistance is read. The pellet resistance, read across terminals B7 and B8, is then compared to the resistance value stored in the PASS-Key II module.

If the Key Resistance Pellet is of the proper resistance, the PASS-Key II module grounds terminal A4, energizing the Starter Enable Relay. At the same time, the module provides the cranking fuel enable signal at terminal A3 to inform the Powertrain Control Module (PCM) to allow fuel to flow.

If the resistance is incorrect, the PASS-Key II module shuts down for approximately three minutes. During this interval, there is no output at A3 or A4 and the SECURITY indicator illuminates. The Ignition Switch input is ignored during this shut down period. For this reason, the timer will run and the SECURITY indicator remains illuminated with Ignition ON or OFF.

Once the timer expires, the next time the Ignition Switch is cycled from OFF to ON, the PASS-Key II module timer is reset. A key having the correct code can then be used to start the engine.

Security Indicator Operation - PASS-Key II
The PASS-Key II system controls the SECURITY indicator. In normal operation, the PASS-Key� II module controls the lamp only when the ignition is ON. There are four PASS-Key II system bulb modes as follows.
1. Bulb Check. When the ignition is first turned on, the SECURITY indicator illuminates for approximately 5 seconds to indicate the system is operating correctly. Refer to the following bulb symptoms, if the bulb check does not operate.
2. Bulb Stays Illuminated and Engine Starts. If the SECURITY indicator stays illuminated after the engine starts, this is an indication that the PASS-Key II module is reading an open, short or incorrect resistance value. Verify that the PASS-Key� II module connection at the base of the steering column is properly connected and that a good ignition key is being used.
3. Bulb Stays Illuminated and Engine Does Not Start. If the SECURITY indicator stays illuminated while and after attempting to start the engine and the engine does not crank or start, this indicates that the PASS-Key II module has sensed an improper key value and has disabled the engine and set the disable timer. This specifically does not mean that the key sense circuit is open or shorted to chassis ground, refer to "Bulb Flashes and Engine Does Not Start". Remove the key from the ignition and verify that is the correct key code for the vehicle. The key code may be checked using tool J 35628-A and comparing the key code to that of other keys for the vehicle. After waiting approximately 3 minutes for the disable time to expire and the SECURITY indicator to go out, try to start the engine with a known good key with the proper key code.
4. Bulb Flashes and Engine Does Not Start. If the SECURITY indicator flashes once per second and the engine does not start, this indicates that the PASS-Key II module sensed an open, a short or otherwise invalid (value matched none of the available 15 key codes) input from the ignition key resistor input. The PASS-Key II module does not start the disable timer during this operation mode. This operation mode could also be caused by a malfunctioning power or ground circuits.