Hello .. thanks for the donation .. much appreciated
Vehicle Theft Deterrent (VTD) Description and Operation
Passlockà † System
The Passlockà † System is provided in order to prevent vehicle theft if the ignition lock cylinder is forced to rotate or the ignition switch is operated while separated from the ignition lock cylinder case. If starting is attempted without authorization from the Passlockà † System, the powertrain control module (PCM) will disable engine starting. Start disable may be in the form of fuel disable or starter disable, depending on engine application.
The components of the Passlockà † System are as follows:
The ignition lock cylinder and key
The ignition lock cylinder case, including the Passlockà † sensor
The ignition switch
The body control module (BCM)
The security indicator on the instrument cluster
The powertrain control module (PCM)
Ignition Lock Cylinder Case, Including the Passlockà † Sensor
The ignition lock cylinder fits inside the ignition lock cylinder case and operates the ignition switch when turned by a key with the proper mechanical cut. When the ignition key is used to turn the ignition lock cylinder to crank, start, a magnet on the lock cylinder passes close to the Passlockà † sensor within the ignition lock cylinder case. The magnet activates the security hall effect sensor in the Passlockà † sensor which completes a circuit from the security sensor signal circuit through a resistor to the security sensor low reference circuit. The resistance value will vary from vehicle to vehicle.
If a magnet from outside of the ignition lock cylinder case is used to attempt to steal the vehicle, the tamper hall effect sensor will be activated. This completes a circuit from the security sensor signal circuit through a tamper resistor to the security sensor low reference circuit bypassing the security resistor. If the ignition switch is forced to rotate without the correct key, or if the ignition lock cylinder is removed by force, the Passlockà † sensor will be damaged and will not operate.
Ignition Switch
The ignition switch contains the wiring and electrical switching portion of the column mounted ignition assembly. The ignition switch includes wiring pigtails which connect it to the base of column connector, the Passlockà † sensor on the ignition lock cylinder case, and other components. The wiring for the Passlockà † sensor is unaffected by ignition switch position. The electrical switch portion is operated by the key and lock cylinder when they are rotated within the ignition lock cylinder case. The ignition switch operates the crank relay regardless of the status of the Passlockà † System.
Body Control Module (BCM)
The body control module (BCM) contains the logic of the Theft Deterrent System. The BCM provides the battery positive voltage to operate the Passlockà † sensor. The BCM also measures the voltage of the security sensor signal circuit. The voltage measured will indicate whether the Passlockà † sensor has been activated and whether the resistance value from the sensor is a valid value or the tamper value. If voltage measured is in the valid range, the BCM compares this voltage, voltage code, to a previously learned voltage code. If the voltage codes match, the BCM sends a class 2 message containing a password to the powertrain control module (PCM). If the voltage codes do not match, or the voltage is in the tamper range, or there is a circuit fault, the BCM will not send the correct password to the PCM, and the vehicle will not start.
Powertrain Control Module
The powertrain control module (PCM) contains the remainder of the logic of the Theft Deterrent System. If a class 2 message containing a valid password is received from the body control module (BCM), the PCM will continue to allow the fuel injectors to operate. The PCM will allow the fuel injectors to operate until it decides there is no valid password coming from the BCM. If the PCM does not receive a class 2 message, or receives a class 2 message with an incorrect password, the engine will crank and will not run or will start and stall immediately.
Theft System Indicator
The IPC illuminates the theft deterrent indicator as determined by the theft deterrent system. The IPC receives a class 2 message from the BCM requesting illumination.
The vehicle theft deterrent (VTD) system requests the IPC to illuminate the indicator only when the ignition switch is ON.
The content theft deterrent (CTD) system requests the IPC to illuminate the indicator only when the ignition switch is in the OFF or ACC positions or during RAP.
The body control module performs the displays test at the start of each ignition cycle. The indicator illuminates for approximately 3 seconds.
Fuel Lockout Cycle
When it receives a password which is incorrect or a password which indicates tamper and the powertrain control module (PCM) disables the fuel injectors, the fuel injectors remain disabled for 10 minutes even if the ignition switch is turned from the RUN position to the OFF position.
Changing the Passlockà † Components
The following components contain codes or passwords, or must learn codes or passwords for the Passlockà † System to allow the vehicle to start:
The ignition lock cylinder case
The body control module (BCM)
The powertrain control module (PCM)
If any of these parts are replaced, a learn procedure must be performed. Refer to Programming Theft Deterrent System Components. If parts are replaced and a learn procedure is not performed, the engine will crank and will not run or will start and stall immediately.
Programming Theft Deterrent System Components
Programming Replacement Passlockà † Sensor, BCM, or PCM
IMPORTANT:The body control module (BCM) must be programmed with the proper RPO configurations before performing learn procedures. See Body Control Module (BCM) Programming/RPO Configuration .
If replacing the BCM with a GM Service Parts Operations (SPO) replacement part, the module will learn Passlockà † sensor data code immediately. The existing PCM however, must learn the new fuel continue password when the BCM is replaced.
If replacing a PCM with a GM Service Parts Operations (SPO) replacement part, after programming, these modules will learn the incoming fuel continue password immediately upon receipt of a password message. Once a password message is received, and a password is learned, a learn procedure must be performed to change this password again. A PCM which has been previously installed in another vehicle will have learned the other vehicle's fuel continue password and will require a learn procedure after programming to learn the current vehicle's password.
Conditions
Use this procedure after replacing:
Passlockà † Sensor
BCM
PCM
****Learn Procedures*****
There are two available methods to perform the programming procedure:
A 10 minutes procedure which requires a Tech 2 and a techline terminal.
A 30 minutes procedure which does not require the use of any tools.
10 Minute Learn Procedure
Tools Required
Tech 2 Â
Techline terminal with current SPS (Service Programming System) software
Connect the Tech 2 Â to the vehicle.
Select "Request Information" under "Service Programming".
Disconnect the Tech 2 Â from the vehicle and connect it to a techline terminal.
On the techline terminal, select "Theft Module Re-Learn" under "Service Programming".
Disconnect the Tech 2 Â from the techline terminal and connect it to the vehicle.
Turn ON the ignition, with the engine OFF.
Select "VTD Re-Learn" under "Service Programming".
Attempt to start the engine, then release the key to ON (vehicle will not start).
Observe the SECURITY telltale, after approximately 10 minutes the telltale will turn OFF (the vehicle is now ready to relearn the Passlockà † Sensor Data Code and/or password on the next ignition switch transition from OFF to CRANK).
Turn OFF the ignition, and wait 5 seconds.
Start the engine (the vehicle has now learned the password).
With the Tech 2 Â (scan tool), clear any DTCs.
*****30 Minute Learn Procedure*******
Turn ON the ignition, with the engine OFF.
Attempt to start the engine, then release the key to ON (vehicle will not start).
Observe the SECURITY telltale, after approximately 10 minutes the telltale will turn OFF.
Turn OFF the ignition, and wait 5 seconds.
Repeat steps 1 through 4 two more times for a total of 3 cycles/30 minutes (the vehicle is now ready to relearn the Passlockà † Sensor Data Code and/or passwords on the next ignition switch transition from OFF to CRANK).
IMPORTANT:The vehicle learns the Passlockà † Sensor Data Code and/or password on the next ignition switch transition from OFF to CRANK. You must turn the ignition OFF before attempting to start the vehicle.
Start the engine (the vehicle has now learned the Passlockà † Sensor Data Code and/or password).
With a scan tool, clear any DTCs if needed (history DTCs will self clear after 100 ignition cycles).
Hope this helps
SPONSORED LINKS
Friday, February 26th, 2010 AT 4:31 AM
