2002 Chevy Malibu 2002 Malibu "Theft system light rema

Was the light on before you replaced the cylinder? Essentially you replaced the passlock sensor, and all it shows is a 10 minute learn procedure. There are a few key possibilities that come up. First it states that all DTCs have to be cleared before the relearn, another part of the 10 minute procedure is that the key has to be cycled to start and released to run, and after 10 minutes the indicator should go off. The vehicle already starts and runs though. I would guess that there are trouble codes in the system that are requesting the indicator to be on. To find out what these codes are, will require a scan tool. I don't believe that a general code read will interrogate the theft system. That usually will only get you emissions, or PCM trouble codes.

You are going to have to answer the presently unknown, are there any fault codes that have the indicator requested. There are at least 6-7 troble codes that will request its illumination, and they store in the BCM(body control module).

Included is the description and operation of the system.

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:

"Â The ignition lock cylinder and key

" The ignition lock cylinder case, including the Passlockà † sensor

"Â The ignition switch

"Â The body control module (BCM)

"Â The security indicator on the instrument cluster

"Â 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.

"Â The vehicle theft deterrent (VTD) system requests the IPC to illuminate the indicator only when the ignition switch is ON.

"Â 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.

"Â 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:

"Â The ignition lock cylinder case

"Â The body control module (BCM)

"Â 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.

Since the vehicle starts and runs, you have already programmed or 'learned' the theft system components. Like I said, you would need to extract the fault codes to move any further. Without knowing if/what fault may be turning the light on, you don't have much direction.