Mechanics

SECURITY SYSTEM

1997 Buick Lesabre

Computer problem
1997 Buick Lesabre 6 cyl Front Wheel Drive Automatic 131000 miles

I drove my car home from grocery store and cut the engine off and when I went to restart it would not budge. Fuel pump is shut down and switch is, too. Could this be due to security system? We know it isn't the battery since we have checked everything else. Any info you could give me will be greatly appreciated. Thank you.
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Raymond loggins
October 11, 2008.



Hello, when you say shut down, does that mean you turn the key and get no noise, movement at all, or it tries to start and doesn’t? When you turn the key on do the dash lights for starting the car come on? Do you have a way to check/pull the codes? Auto Zone has the loan a tool program and you can use their scanner. The security sytem, I have attached info on that. The security light should be flashing, the ignition is only off for 3 minutes but it says nothing about the fuel pump. Which goes back to does the car try to start? Please provide more info if the supplied does not help.

The Universal Theft Deterrent System (RPO UA6) operates separately from the Personal Automotive Security System (PASS-Key(R) II). The system is designed to provide a warning in the event of force entry through the doors and trunk. When a forced entry is attempted, the alarm warning system trips causing the horn to sound intermittently and the exterior lamps to flash in unison for approximately 3 minutes . The universal theft deterrent system does not affect engine starting.

The alarm is tripped by closing switches strategically located in the door latch assemblies and the trunk lid lock cylinder tamper switch. If any door is opened or trunk lid lock cylinder violated by rotating or moving in and out without the key, the controller activates the alarm.

General Info on the Security System

The PASS-Key ½ 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 ½ II decoder module.

The PASS-Key(R) II decoder module controls the starter enable relay and the Powertrain Control Module (PCM) fuel enable input. If the PASS-Key(R) II decoder 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, located in the Ignition Key Lock Cylinder, make contact the with the key resistor pellet on the key when it is inserted. Rotating the lock applies ignition voltage to the PASS-Key(R) II decoder module, allowing the module to read the pellet resistance across terminals B7 and B8. The module compares the pellet resistance to the resistance value stored in the module.

If the key resistor pellet has the proper resistance, the PASS-Key(R) II decoder 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 PCM to allow fuel to flow.

If the resistance is incorrect, the PASS-Key(R) II decoder module shuts down for approximately three minutes. During this interval, there is no output at terminal A3 or A4 and the "SECURITY" indicator illuminates. The module ignores the ignition switch input during this shutdown period. For this reason, the timer runs and the SECURITY" indicator remains illuminated with ignition ON or OFF.

Once the timer expires, the next time the ignition switch cycles from "OFF" to "ON," the PASS-Key(R) II decoder module timer resets. A key having the correct code can then be used to start the engine

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ImpalaSS
Oct 11, 2008.