2002 pontiac montanna van will not start.security light is flashing on.might be in theft mode

The security, antitheft or lock picture/icon is a visual indication that something in the car's antitheft system is failing. In most GM cars and trucks there is a hidden system that most people are unaware even exists. From the moment you put your key in the ignition, there begins a constant line of communication between your key's security chip or transponder, to the ignition's lock cylinder, and then to the car's TDM (Theft Deterrent Module). These 3 parts are in CONSTANT communication. If the key is in the ignition, then these parts are sending signals to each other. The security light illuminates when that signal gets broken, even just for a second. When the signal breaks, the car misinterprets this as an attempt at theft and goes into antitheft mode. The car thinks its being stolen or hotwired because it is not getting that signal from YOUR specific key. This is why the security light turns on and shuts down your vehicle. This link explains it pretty well.
http://www.diy-gm-security.com/

You don't need to bleed it really. If you start the vehicle and turn the wheel all the way from side to side and turn it off then repeat a few times the air will purge automatically.

If you need further help, I’m available over the phone at https://www.6ya.com/expert/justin_3ae27a9d61d6acd4

abs not going to be the cause...possible passlock security system problem....does the security light flash rapidly when it wont start? it is common for the security system to act up on these vehicles

The remote needs to work if the vehicle originally came with the remote from the factory. It gives off a signal to the ring around the ignition switch to deactivate the alarm.

you could have a bad alternator not keeping the system at the appropriate level of charge. Or check the battery, replace with other known battery that is good and see if this fixes the problem. Clean all battery terminals. Dead shorts in battery can really create problems and sometimes can load test good but on the low side. Try the battery swap first if you have access to one

Here's a trouble shooting guide.Trouble Code: P1632

Theft Deterrent Fuel Disable Signal Received

Possible Causes:


Perform the Powertrain Onboard Diagnostic System CheckPassword Learn Procedure - Attempt to start the vehicle (leave the ignition "on"). The Theft System telltale will flash for 4 seconds and then remain "on" for 10 minutes. Theft System Learn Mode will display Disabled on the Scan ToolTurn the ignition "off" after the Theft System telltale goes "out".Repeat steps 1 and 2 two more times. After the Theft System telltale turns "off" on the 3rd key cycle, and Theft System Learn Mode will display Enabled on the Scan Tool, attempt to start the engine. Once the engine starts the password is learned.

If you are dealing with the anti theft the anti theft will flash as you are trying to start the vehicle if this is the case then it is the anti theft if not then you are not dealing with a ant theft issue. You can do a 30 minute relearn procedure without a scan tool. here is how Turn ignition on without the engine reunning.attempt to start the vehicle then release the key to ON.(vehicle doest start) Observe the security light.afeter 10 minutes the security light will turn off.Turn off the ignition and wait 5 seconds.do this 3 times for 30 minutes. start the engine with the engine started the vehicle will learn the passlock key.

Gm vehicles have been known to have faulty anti theft security systems. One of the symtoms of this is when your vehicle starts for 1-5 seconds and then stalls. A good way to know if this is the problem is when you see a light on the dash that says SECURITY. If you see this light flashing or on solid, this explains the van not starting. This link might help you

http://vatspasslockpasskeysecurityhelp.yolasite.com/

The vehicle theft deterrent system is designed in order to prevent vehicle theft by disabling the fuel injectors unless the lock cylinder is correctly engaged by a mechanical key. The theft deterrent system uses the following 4 components for theft prevention:
• The lock cylinder
• The ignition switch
• The body control module (BCM)
• The powertrain control module (PCM)
When starting the engine, the PCM searches for a password from the BCM through the Class 2 serial data circuit. If the password is not recognized or not present, the PCM will disable the engine. Two modes of tamper detection are provided:
No password received
The engine will start and stall quickly. SECURITY telltale will flash on the instrument panel cluster (IPC) and then stay ON steady.
Incorrect or disable password received (More than 3 invalid passwords are received)
The engine is disabled for at least 10 minutes and the SECURITY telltale will illuminate solid on the IPC during the 10 minutes.
After the vehicle has passed theft detection, the PCM will continue normal operation.

Passlock™ Lock Cylinder
The Passlock™ lock cylinder is a locking cylinder that turns a rotating magnet past a stationary hall effect sensor. This action creates the Passlock™ cylinder data. The Passlock™ cylinder data is sent to the Body Control Module (BCM). The Passlock™ lock cylinder is interfaced with the BCM via a 3-wire connection:
• Power
• Ground
• Data

Powertrain Control Module (PCM)
The Powertrain Control Module (PCM) is located on the lower left side of the instrument panel.
The PCM communicates with the Body Control Module (BCM) via serial data over the class 2 serial data bus, CKT 1807. When the BCM determines a passed theft condition, the BCM sends a coded password to the PCM. When the PCM receives the correct password, the PCM enables the fuel injection system, allowing the vehicle to operate correctly. The PCM may allow the car to start and quickly stall during a failed theft condition.
The following conditions may cause the PCM to enter a tamper mode:
• A bad timing cycle
• An incorrect password
If the BCM does not receive a password within a preset time window, the BCM will enter a short tamper mode. During this mode, the PCM will not allow the car to operate for 4 seconds.
If the password is incorrect, the PCM will enter the long tamper mode. In the long tamper mode, the following actions will occur:
• The THEFT SYSTEM indicator will flash.
• The fuel injectors will be shut off for approximately 10 minutes.
Although the vehicle may start, the engine will quickly stall due to a fuel cut-off.
In the event of an open in the serial data communication between the BCM and the PCM, the following actions occur:
• The PCM will become fail-enabled if the car has already passed theft for that ignition cycle (i.e. the engine is running).
• The PCM may set the diagnostic trouble codes (DTC).
• The THEFT SYSTEM indicator will light continuously.
• The PCM will become fail-enabled for future ignition cycles.
If a failure occurs in serial data before the ignition cycle, while the PCM is not fail-enabled, the PCM will never receive a valid password in order to enable the continued use of the fuel injectors.

Your best bet , take to a qualified repair shop .
DTC B2947 Security System Sensor Power CKT Low
DTC B2948 Security System Sensor Power CKT High
DTC B2957 Security System Sensor Data Circuit Low
DTC B2958 Security System Sensor Data Circuit High
DTC B2960 Sec Sys Sensor Data Incorrect but Valid
DTC B3031 Security System Controller in Learn Mode
DTC B3033 Security System Indicates Tamper

sounds like either low battery voltage or the van has entered theft mode.. good luck..