General Motors Vehicles Equipped with PASSLock

The PassLock system was designed to prevent vehicle theft by disabling fuel to the engine if attempts are made to start the vehicle without the correct bitted key. PASSLock increased the level of security while retaining the ease of service and costs offered by standard ignition lock systems. Unlike...



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The PassLock system was designed to prevent vehicle theft by disabling fuel to the engine if attempts are made to start the vehicle without the correct bitted key. PASSLock increased the level of security while retaining the ease of service and costs offered by standard ignition lock systems. Unlike the General Motors PASSKey I/II, VATS, PASSKey III, or keyless, the security of the PassLock system is built into the lock and is not dependent on a specialized key or separate device.

NOTE: For the purpose of this article, the terms PassLock, Magnetic Resonance Device (MRD) and Vehicle Theft Deterrent (VTD) are interchangeable.

No programming is required for the PASSLock-equipped vehicle to accept additional keys. Any key blank with the proper profile cut to the correct depths can be used to operate the ignition lock.

For the 1995-1/2 model year, General Motors introduced PASSLock, the first ignition lock equipped with a magnet mounted into the ignition lock cylinder and a corresponding Hall-effect sensor mounted into the housing assembly. When the correctly cut key is inserted into the lock cylinder and rotated, the magnet registers on the sensor’s three switch points. The sensor electronically signals the vehicle’s on-board computer, and the fuel supply remains on if the electronic value matches the code stored in the computer.

If the values do not match, the fuel supply is shut off. After three consecutive failed attempts, PASSLock will enter Long Tamper Mode, disabling the engine for 10 minutes while the Theft System indicator on the instrument panel flashes.

The PASSLock system is designed such that forced rotation normally damages the electronics, immobilizing the vehicle. According to General Motors, should the ignition lock be force rotated, the lock must be replaced in order to operate the vehicle.

Note: The theft deterrent function of the PASSLock System locks out the fuel injectors after the engine is started. However, before a tamper mode engages, the car may run for a few seconds. The engine will then stall.

PASSLock was developed for the General Motors 10-cut lock mechanism. There are three basic styles of PassLock ignition locks: Modular, Modular in-dash, and CSS. When purchasing a replacement ignition lock, make sure the part number is correct for the year, make, and model. PASSLock ignition locks vary by the version (PASSLock I or II), the type of connector, and if wired, the length of the wire. Installing the incorrect ignition lock will usually result in the vehicle not being operable.

Depending upon the year and the model, replacing the ignition lock can result in the need to disassemble the dashboard. Early vehicles equipped with the modular PASSLock ignition locks had a long wire that went from the ignition switch to a connector behind the instrument panel. The modular in-dash ignition locks and the CSS ignition lock cylinders do not have wiring that must be plugged in.

When replacing a PASSLock ignition lock, there is a one in 10 chance the Hall effect sensor is the same value as the lock being replaced. Replacement locks do not have an identified sensor value. When the starter is engaged for the first time and the engine starts but stalls, the instrument panel security light will flash, indicating the vehicle is in the secure mode (it will not start) and must be programmed to accept the new lock.

Note: To avoid programming when the ignition lock needs to be replaced, use the housing of the ignition lock, which contains the Hall-effect switch. Replace only the plug. The Hall-effect switch determines the magnetic value.

To reprogram PASSLock I ignition lock:

Step 1. After replacing the lock, try to start the vehicle with a correctly cut key. There is a one in 10 chance that the car will start.

Step 2. If the new lock does not match the electronic value in the vehicle’s computer, an indicator light on the instrument panel will begin flashing and the car will be disabled.

Step 3. Leave ignition in the ON or RUN position.

Step 4. After approximately 10 minutes, the light will stop flashing and remain ON. The onboard computer has then been programmed to accept the new lock’s signal. The car can be started.

If the indicator light turns off, the vehicle is probably equipped with a PASSLock II system. Continue with the following programming procedure.

To reprogram PASSLock II ignition lock:

Step 1. After replacing the lock, try to start the vehicle with a correctly cut key. There is a one-in-10 chance that the car will start.

Step 2. If the new lock does not match the electronic value in the vehicle’s computer, an indicator light on the instrument panel will begin flashing and the car will be disabled.

Step 3. Leave ignition in the ON or RUN position.

Step 4. After approximately 10 minutes, the light will stop flashing and turn OFF.

Step 5. Turn the ignition on and back to the ON or RUN position.

Step 6. After approximately 10 minutes, the light will stop flashing and turn OFF.

Step 7. Turn the ignition on and back to the ON or RUN position.

Step 8. After approximately 10 minutes, the light will stop flashing and remain ON. The onboard computer has then been programmed to accept the new lock’s signal. The vehicle can now be started.

Occasionally, a PASSLock-equipped vehicle will have problems starting. The following information can help to determine the cause of the problem.

The PASSLock system does not disable the starter; it only disables the fuel after the engine has started. If the vehicle will not crank, PASSLock cannot cause this condition. If the vehicle starts, but stalls quickly, this condition can possibly be related to PASSLock.

Most PASSLock-equipped vehicles have a telltale indicator in the instrument panel. When a PASSLock-equipped vehicle is being started, the instrument panel warning light for PASSLock remains on until the engine starts. For this reason a “No Start” condition should not be confused with PASSLock System fault.

Following is a list by model year of the General Motors vehicles that have been and are equipped with the PASSLock Anti-Theft System.

Buick Rainier 2002, 2003
Buick Skylark 1995, 1995-1/2, 1996
Cadillac Escalade 1998-2004
Chevrolet Cavalier Z24 1995-1/2
Chevrolet Cavalier 1995-1/2-2004
Chevrolet Cobalt 2004
Chevrolet Impala 1998-2004
Chevrolet Malibu 1996-2003
Chevrolet Monte Carlo 2000-2005
Chevrolet Astro Van 1996-2004
Chevrolet Express van 2002-2005
Chevrolet Full size pickup 1997, 1998
Chevrolet S-10 Blazer 1996-2003
Chevrolet S-10 pickup 1997-2004
Chevrolet Silverado 1997-2004
Chevrolet Sport Van 1997-2000
Chevrolet SSR 2002, 2003
Chevrolet Suburban 1997-2002
Chevrolet Tahoe 1998-2005
Chevrolet Trailblazer 2001-2004
GMC CK pickup 1997, 1998
GMC Envoy 2000-2003
GMC Jimmy 1996-2002
GMC Safari Van 1997-2004
GMC Savanna Van 2001-2004
GMC Sierra 1997-2003
GMC Sonoma pickup 1997-2003
GMC Suburban 1997-2002
GMC Vandura/Rallye 1997-2000
GMC Yukon 1996-2003
Hummer H2 2001-2003
Isuzu Hombre 1997-2001
Isuzu Ascender 2002-2004
Oldsmobile Achieva 1995-1/2-1997
Oldsmobile Alero 1998-1999
Oldsmobile Bravada 1997-1999
Oldsmobile Cutlass 1996-1998
Oldsmobile Intrigue 1997-1999
Pontiac Grand Am 1995-1/2-2003
Pontiac Sunfire/GT 1995-1/2-2004
Saturn Ion 2001-2003
Saturn L300 2000-2003
Saturn Vue 2000-2003

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