Have a 99' right hand blazer built for the UK market. For insurance puposes on import all blazers were fitted with a secondary alarm. This device I'm told goes wrong after time and prevents the starting of the vehicle from working properly. So I disconnected it and all was fine except we have to manually lock the doors, otherwise the hazards flash constantly (flat battery syndrome). Some mobile phone masts interfer with the operation of the standard alarm system, rendering the car disabled. Can anyone give any info on the problem which must be prevailant with the UK model?Thanks,Gav

 

Wow... I never knew they changed them that extensively for import into the UK... With most all of us located in North America, the chances that we would be able to help you out are not pretty... My best advice would be to get in contact with the service department at a local Chevy dealer near you and see if they can give you some wiring diagrams. With diagrams, I can help you out, but I don't have a clue what they add for over there... Sorry

 

gCookman
I have same machine currently stranded because of immobiliser failure!
How did you solve your problem? moonraker

 

Maybe this can help you:

These are internal repair documents from (2005) GM Service Information DVD that I found on E-bay...it may cover your situation.

Document ID# 560386
2000 Chevrolet/Geo Blazer - 4WD - RHD

Content Theft Deterrent (CTD) Description
Content Theft Deterrent (CTD) System
The theft deterrent system on this vehicle is comprised of 2separate systems. The systems are the Passlock system and the content theft deterrent (CTD) system. There are separate description and diagnosis procedures within this section. The CTD function provides the theft deterrent by sounding the horn and flashing the headlamps and the parklamps when there is an unauthorized vehicle entry or there is tampering detected.
Body Control Module (BCM)
The body control module (BCM) monitors several inputs in order to arm and disarm the CTD system. The BCM controls the alarm function outputs. When the BCM detects an unauthorized entry (any door opened), the BCM applies ground to the horn, the park lamp and the headlamp relays. The BCM will send messages to the security indicator in the instrument cluster through the Class2 serial data link. The BCM has the following 8basic modes for operating the CTD system. The more detailed descriptions are below.

• Off state
• Idle state
• Disarmed state
• Ready-to-arm state
• Arm initiated state
• Arm delay state
• Armed state
• Alarm state

The BCM has the following 6discrete inputs in order to monitor the CTD system:

• Ignition1
• Driver door mini-wedge (door jamb) switch
• Passenger door mini-wedge (door jamb) switch
• Door lock relay
• Door key switch
• Passenger door unlock relay

The BCM applies ground once per second for approximately 2minutes, or until a valid input to disarm the system is received by the BCM.
Door Mini-Wedge (Door Jamb) Switches
The theft deterrent system uses the door mini-wedge switch as one method in order to activate the alarm. If the BCM detects any door opening before the BCM receives a disarm input, the alarm mode activates.
Door Key Switch
The BCM monitors the door key switches in order to disarm the CTD system. When the lock cylinder turns in order to unlock the door, the switch grounds the disarm input to the BCM.
Remote Control Door Lock Receiver Module System
The remote control door lock receiver module system may also arm and disarm the CTD system. When the remote control door lock receiver receives a door lock or an unlock signal from the key fob, the remote control door lock receiver sends a message to the BCM. The message orders the BCM to perform the appropriate door lock/unlock command. The BCM detects the message and performs one of the following functions:

• Locks the doors and enters the armed initiated mode
• Unlocks the doors and enters the ready-to-arm mode

Off State
The CTD system will be in the off state when the ignition switch is in the RUN position and all the doors are closed. The BCM will request the security indicator to remain OFF.
Idle State
The CTD system will be in the idle state when the ignition switch is in the RUN position and any door is open. The BCM will request the security indicator to remain OFF.
Disarmed State
The CTD system will be in the disarmed state when the ignition switch is in the LOCK (off) position and all the doors are closed. The BCM will request the security indicator to remain OFF.
Ready-To-Arm State
The CTD system will be in the ready-to-arm state when the ignition switch is in the LOCK (off) position and any door opens. The BCM will request the security indicator to flash.
Arm Initiated State
The CTD system will be in the arm initiated state when the ignition switch is in the LOCK (off) position, any door opens, and the BCM detects a lock command from either the power door lock switch or the remote control door lock receiver. The BCM will request the security indicator to remain ON.
Arm Delay State
The CTD system will enter the arm delay state when the ignition switch is in the LOCK (off) position, the BCM receives a LOCK command from either the power door lock switch or the remote control door lock receiver and all the doors are closed. The BCM will request the security indicator to remain ON for 15 seconds.
Armed State
The CTD system will enter the armed state after the 15 second delay of the arm delay state, unless the BCM detects any door opening within that time. The BCM monitors the inputs (listed above) in order to determine whether to activate the alarm or to disarm the system. The BCM will request the security indicator to remain OFF.
Alarmed State
The CTD system will enter the alarmed state from the armed state if any door opens. The horns and the exterior lights will alternate off and on for approximately two minutes or until an unlock command is received by the BCM. If the BCM does not receive an unlock command, the CTD system will go back to the armed state. The BCM will request the security indicator to remain off. The CTD system will change from the alarm state to the off state if the vehicle control module (VCM)/powertrain control module (PCM) receives a valid Passlock ignition key rotation.
Remote Panic Alarm/Vehicle Locator State
The CTD system will enter the remote panic alarm/vehicle locator state when the panic button on the key fob is pressed. When the panic button is pressed, the remote control door lock receiver sends a message to the BCM. The BCM will sound the horns and flash the headlamps and the parklamps. You can disable the remote panic alarm/vehicle locator state by pressing the panic button on the key fob again or the system will time out after 30 seconds.


Here is a companion document...

Document ID# 624126
2000 Chevrolet/Geo Blazer - 4WD - RHD

Vehicle Theft Deterrent (VTD) Description
Passlock System
The theft deterrent system has been incorporated into the body control module (BCM). The theft deterrent is provided in order to prevent the vehicle operation if the correct key is not used in order to start the vehicle. The ignition key turns the lock cylinder. The cylinder rotation produces an analog voltage code in the Passlock sensor. This voltage code is received by the BCM. The BCM compares the voltage code to the previously learned voltage code. If the codes match, a class 2 message is sent from the BCM to the vehicle control module (VCM). The message enables the fuel injectors.
The design of the Passlock system is to prevent vehicle theft by disabling the engine unless the ignition lock cylinder rotates properly by engaging the correct ignition key. The system is similar in concept to the passkey system. However, the Passlock system eliminates the need for a key mounted resistor pellet. The components of the Passlock system are as follows:

• The ignition lock cylinder
• The ignition switch
• The Passlock sensor
• The body control module (BCM)
• The security indicator
• The vehicle control module (VCM)

Ignition Lock Cylinder and Housing
The ignition lock cylinder is located at the upper right side of the steering column. The Passlock sensor is in the steering column. The Passlock sensor is separate from the key and lock cylinder. The key and the lock cylinder work together in order to determine if the proper ignition key was used to start the vehicle.
In the event of an open Class 2 serial data line between the BCM and the VCM, the vehicle will become fail-enabled if the VCM has already received the password from the BCM for that ignition cycle (the engine is running). In this event, the following conditions occur:

• The security indicator will be ON continuously.
• The VCM will become fail-enabled for future ignition cycles.

If a failure in the Class 2 serial data line occurs before the ignition cycle, when the VCM is not fail-enabled, the following conditions occur:

• The VCM will never receive a valid password in order to enable the fuel injectors.
• The vehicle will not start.

Ignition Switch
The lock cylinder and the visible key insert portion of the ignition switch are located at the upper right side of the steering column. The electrical switching portion of the assembly is separate from the key and lock cylinder. The electrical switch portion is hidden inside the steering column. The electrical switch portion and the key and lock cylinder synchronize and work in conjunction through the action of the mechanical assembly between the 2 parts.
Passlock Sensor
The Passlock sensor is inside the upper right side of the steering column. The Passlock sensor contains 2 hall effect sensors. The tamper hall effect sensor is on the top. The security hall effect sensor is under the tamper hall effect sensor. Both of the hall effect sensors monitor the magnet of the lock cylinder through an opening. The tamper hall effect sensor is physically placed on top of the security hall effect sensor. This arrangement enables the tamper hall effect sensor to engage first if an intruder attempts to bypass the Passlock sensor by placing a large magnet around that area of the steering column. There is a tamper resistor inside the Passlock sensor in order to help prevent tamper to the system. Passlock equipped vehicles have a selection of 10 different security resistors ranging from 0.5K ohms up to 13.6K ohms. Installing one of the security resistors inside the Passlock sensor will generate a unique Passlock code. All 10 combinations of the Passlock sensor have the same part number. However, you cannot simply replace the Passlock sensor and expect the system to operate properly. Always start by performing the Diagnostic System Check first and following the instructions.
Body Control Module
The Body Control Module (BCM) contains the theft deterrent system logic. The BCM reads the Passlock data from the Passlock sensor. If the Passlock data is correct, the BCM will pass theft. The BCM will then transmit the code password to the VCM.
During the tamper mode the vehicle may start. The vehicle will then stall. If the BCM receives the wrong Passlock data, the VTD will immediately go into the tamper mode. The tamper mode will lock-out the vehicle fuel injectors for 10 minutes. The SECURITY indicator will flash while the VTD is in the tamper mode.
If the Passlock sensor sends a correct password to the BCM when the ignition is in the ON position, the BCM will send a fuel enable signal to the VCM. The VCM will not disable the fuel due to any BCM message for the remainder of the ignition cycle.
SECURITY Indicator
The SECURITY indicator appears at the instrument cluster. If the SECURITY indicator flashes or if the SECURITY indicator lights continuously during the vehicle operation, refer to the system diagnosis.
Vehicle Control Module
The VCM communicates with the BCM over the Class 2 serial data line. When the BCM determines a no start condition, it sends a Class 2 serial data password to the VCM in order to disable the fuel injection system. If the BCM receives the expected voltage from the Passlock sensor, the BCM sends a class 2 serial data password to the VCM in order to enable the fuel injection system. The VCM then allows the vehicle to start correctly. If the Class 2 serial data password from the BCM to the VCM is not within the Vehicle Security Status Message, the fuel injectors will shut OFF during a start attempt. The SECURITY indicator will be illuminated for 10 minutes. If the VCM does not receive the same password from the BCM as the last learned one, the vehicle will start and then stalls due to the Fuel Lockout.
Fuel Lockout Cycle
The Passlock system has a lockout cycle of approximately 10 minutes. Once the vehicle is in the lockout cycle, the vehicle remains in the lockout cycle for 10 minutes, even if the ignition switch is turned from the RUN position to the OFF position.
The Passlock system uses the lockout cycle in order to synchronize all of the Passlock components when any Passlock related part is changed. The Passlock system requires 3 consecutive lockout cycles in order to complete the 30 minute learn procedure for a changed component.
Changing the Passlock Components
The design of the Passlock system is to prevent theft even if the various theft deterrent parts change. The parts that can no longer be changed without the possibility of going into a tamper mode are:

• The Passlock sensor
• The BCM
• The VCM

If you replace any of these parts the vehicle may start and stall for 10 minutes. This is the long tamper mode. If this occurs, the system must go through a long tamper mode cycle. During this time the SECURITY indicator will be flashing for the full 10 minutes and the DTC B3031 will be set. The BCM and the VCM require the full 10 minutes in order to complete a learn cycle. The ignition switch must remain in the RUN position until the SECURITY indicator stops flashing. You will need to repeat the cycle if the ignition switch does not remain in the RUN position. When replacing any of the above parts it is recommended to perform one of the following procedures:

• Seed and Key Procedure (10 minutes). Refer to PASSLOCK Reprogramming Seed and Key .
• Auto Learn Procedure (30 minutes). Refer to PASSLOCK Reprogramming Auto Learn .

 

is there a bit of this missing? it saysarm initiated state then nothing. also, what does it immobilse, is it fuel pump relay, injection module, or just distributor spark. if only distributer spark surely you can just override it totally and forget it as its more trouble than its worth. finally, i see us companies offering pre-programming ecus to your vin but with security disabled. anybody bought one, does it work. any thoughts/advice welcome. brian new member

 

Considering that the original post in this thread is 3+ years old... And the last reply was close to 2 years ago...

We had a problem with the database that cut off a lot of threads. I am sure that if you look for them, you will find many more like this.

I have restored this thread from my email records. I have also copied that post into the Tech Article (DIY) section:
Content & Vehicle Theft Deterrent Information