System Components

PASS-KEY II SYSTEM

SYSTEM COMPONENTS
The ignition key for PASS-Key II equipped vehicles is a typical square ignition key blank and a resistor pellet. The key blank and resistor pellet are not serviceable separately. There are 15 different ignition key assemblies, each with a different resistance valve. The ignition key also has mechanical cuts similar to non-PASS-Key II ignition keys.

IMPORTANT:
When servicing the PASS-Key II system, obtain all ignition keys if possible and verify proper values with tool J 35628-A, VATS interrogator.

STEERING COLUMN LOCK CYLINDER
The steering column lock cylinder in PASS-Key II equipped vehicles contains a set of electrical contacts used to measure the ignition key resistor. The wire routing for the contacts inside the steering column is critical. When servicing the lock cylinder set, be certain to maintain proper wire routing. A forty-eight pin connector at the base of the steering column connects the contacts to the vehicle wiring. The connector is also used for diagnostic purposes.
The steering column lock cylinder also performs all lock cylinder functions similar to non-PASS-Key II vehicles. When replacing column lock cylinder, is necessary to make new keys which match the PASS-Key II key code of the PASS-Key II module and the mechanical cut of the new lock cylinder.

PASS-KEY II MODULE
The PASS-Key II module contains the PASS-Key II system logic. The PASS-Key II module has inputs from the battery and ground circuits, the ignition circuit and the ignition key resistor. The module has outputs to the starter enable circuit, the fuel enable circuit, and the security indicator.

IGNITION INPUT
The ignition input is used to turn the module on. When the module is turned on, it reads the ignition key resistor and controls the outputs accordingly. When the module is turned off the ignition key resistor is not read, and the starter enable relay and fuel enable output do not allow the engine to start. When the ignition is turned off, the battery input to the PASS-Key II module draws about 1 milliamp.

IGNITION KEY RESISTOR INPUT
The ignition key resistor inputs are used to determine if the correct key is being used to start the vehicle. The ignition key resistor inputs are read when the PASS-Key II module is first turned one. If the ignition key resistance value matches the value stored in the PASS-Key II module, the starter enable relay and fuel enable outputs allow the vehicle to start. If the ignition key resistance value does not match the value stored in the PASS-Key II module, the starter enable relay and fuel enable outputs prevent the vehicle from starting. While the vehicle is running, the ignition key resistor inputs are also read. If the PASS-Key II module reads an open, short, or incorrect resistance value for 60 consecutive seconds, the SECURITY' indicator illuminates until the fault is connected for the remainder of the ignition cycle and all subsequent ignition cycles. The PASS-Key II module allows the vehicle to start during this condition.

STARTER ENABLE OUTPUT
The starter enable circuit controls the starter enable relay. When the PASS-Key II module senses the proper ignition key resistance, it grounds the starter enable circuit which allows the engine to be cranked. If the PASS-Key II module does not sense the proper ignition key resistance, it does not ground the starter enable circuit.

FUEL ENABLE OUTPUT
The fuel enable circuit is a PASS-Key II Module output to the PCM. When the PASS-Key II module sees the proper ignition key resistance, it outputs a pulse width modulated (PWM) signal to the PCM. If the PASS-Key II module does not see the proper ignition key resistance, it does not output PWM signal to the PCM.

"SECURITY" INDICATOR OUTPUT
The security indicator circuit is an indicator output. The output is grounded, causing the indicator to light during any one of the following conditions:
^ During a five second BULB TEST at key "ON."
^ Any time the PASS-Key II module is preventing the engine from starting.
^ If the PASS-Key II module is not properly programmed.
^ If the PASS-Key II module has detected an open, short or incorrect resistance for 60 consecutive seconds while the vehicle is running.

STARTER ENABLE RELAY
The starter enable relay does not allow the engine to crank if the correct resistance is not sensed at the ignition key. it prevents the engine from cranking by opening the circuit to the starter solenoid.

POWERTRAIN CONTROL MODULE (PCM)
The PCM reads the fuel enable circuit to determine if the fuel injection should be allowed. If the fuel enable PWM signal is not present, the PCM does not allow fuel injection. If the correct PWM signal is present, the PCM allows fuel injection and normal engine operation.
The PCM has some diagnostic features associated with the PASS-Key II fuel input, including diagnostic trouble codes. Refer to Computers and Controls for details. Powertrain Management