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Canadafix, Auto Technician
Category: GMC
Satisfied Customers: 1632
Experience:  Canadian Class A
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GMC Canyon: is there anyway to disable the passlock security

Customer Question

is there anyway to disable the passlock security system on a 2006 gmc canyon?
Submitted: 5 years ago.
Category: GMC
Expert:  Canadafix replied 5 years ago.
Hello and welcome to Just Answer.

My name is Bernie and I will assist you with your question on Anti theft.

There is no easy way to do this unfortunately.
The systems are tied in to one another and they need to see specific data and voltages.

The modules cannot be removed because they also control many other systems.

If they made these systems easy to disconnect, thieves would certainly learn how to beat the system quickly.

Companies that manufacture after market remote car starters have developed modules to mimic the system already in place but still maintain the integrity of the original setup.

Your questions or comments on this subject are welcome.

Thank you.
Customer: replied 5 years ago.
is there a difficult way? haha im pretty experienced with electronics so it shouldnt be to difficult if there is a way
Expert:  Canadafix replied 5 years ago.

I admire your determination.

Here is a little light reading to begin. Read this through and ask me further questions after this.

Expert:  Canadafix replied 5 years ago.
The Passlock(TM) system is provided in order to prevent vehicle theft if the ignition lock cylinder is forced to rotate. The Passlock(TM) controller reads the coded Passlock(TM) data signal. The data consists of a voltage generated by a voltage divider network created between the Passlock(TM) assembly and the Passlock(TM) controller. If the data is correct , indicating rotation of the lock cylinder with the proper mechanically cut key, then the Passlock(TM) controller sends a password to the powertrain controller via serial data to indicate that fuel should be delivered to the engine. The Passlock(TM) controller also interfaces with the driver displays subsystem to indicate, via a security telltale, the Passlock(TM) subsystem status and acute subsystem failures.

The components of the Passlock(TM) system are as follows:
  • The ignition switch
  • The body control module (BCM)
  • The security indicator on the instrument cluster
  • The engine control module (ECM)

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 the column connector. The Passlock(TM) sensor is an internal resistor within the ignition switch.

The ignition switch receives a 5-volt reference from the body control module (BCM) via the ignition key resistor signal circuit. When in the start position, the 5-volt reference travels through the Passlock(TM) sensor within the ignition switch. This creates a unique voltage value which is returned to the BCM via the off/run/crank voltage circuit.

The body control module (BCM) contains the logic of the theft deterrent system. The BCM provides the 5-volt reference to operate the Passlock(TM) sensor. The BCM also measures the voltage of the off/run/crank voltage. The voltage measured will indicate whether the Passlock(TM) 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 to a previously learned voltage code. If the voltage codes match, the BCM sends a serial data message containing a password to the engine control module (ECM). 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 ECM, and the vehicle will not start.

The engine control module (ECM) contains the remainder of the logic of the theft deterrent system. If a serial data message containing a valid password is received from the body control module (BCM), the ECM will continue to allow the fuel injectors to operate. The ECM will allow the fuel injectors to operate until it decides there is no valid password coming from the BCM. If the ECM does not receive a serial data message, or receives a serial data message with an incorrect password, the engine will crank and will not run or will start and stall immediately.

The instrument panel cluster (IPC) illuminates the security indicator as determined by the theft deterrent system. The security indicator is illuminated when the body control module (BCM) provides a ground on the security indicator control circuit.

  • 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 retained accessory power (RAP).
  • The BCM performs the displays test at the start of each ignition cycle. The indicator illuminates for approximately 3 seconds .

When it receives a password which is incorrect or a password which indicates tamper and the engine control module (ECM) 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.

The following components contain codes or passwords, or must learn codes or passwords for the Passlock(TM) system to allow the vehicle to start:

  • The ignition switch
  • The body control module (BCM)
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.