Service theft system light on, vehicle starts but key is stuck in the ignition

Your vehicle has two theft systems - content theft , if the door is opened without the key or keyless entry key fob the horn honks lights flash . PATS - passive anti-theft system ,this keeps the vehicle from starting if the computers don't see the right code from the transponder pellet in the head of the key .
You can turn off the content theft but not the PATS , when trying to start the vehicle does the theft light flash fast ? Red light on top of the dash .

this will sound odd, but I was having the same issue, and I tried everything on this forum but I wasn't getting anywhere, but I decided to check all my fuses under the dash and found out on my 2010 Ford E350 fuse #54 fuel pump relay coil, was blown, I replaced it and the van started right up, I was having all the issues of a PAT system failure, dash lights on, security light blinking, and advance track service light on.

Does it have anti-theft system ?
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) Do you have a SECURITY light lit on the dash ?

Anti-theft system problem , possibility ! Do you have a security light blinking ? Security Indicator
The security indicator is located in the clock on the top of the instrument panel. The light emitting diode (LED) displays the immobilizer system status. The immobilizer contains the LED driver hardware for direct connection of the LED.
Vehicle Theft Deterrent (VTD) Operation
The immobilizer system design prevents vehicle theft by interrupting the engine operation. The immobilizer system prevents the vehicle from starting. The engine operating functions interrupt if the immobilizer system does not recognize the transponder identification code of the ignition key. The immobilizer system and the content theft deterrent system do not interact. The system includes the following components:
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The ignition key

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The column-mounted theft deterrent module with integrated antenna

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The transponder

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The engine control module (ECM

It's hard to fix something if you don't know how it works ! Fixed ignition ? What did you fix or change ?
SERVICE THEFT SYSTEM
Security: Refer to Theft Systems Description and Operation in Theft Deterrent
You need to have it checked for trouble codes .
The theft deterrent system on this vehicle is comprised of two separate systems, the vehicle theft deterrent (VTD) system and the content theft deterrent (CTD) system. The VTD system prevents drive away theft by keeping the vehicle from starting. The CTD system is the vehicle alarm system which discourages unauthorized entry into the vehicle. These systems are described and diagnosed separately within this section.
Theft System Indicators
SECURITY The instrument panel cluster (IPC) illuminates the SECURITY indicator as determined by the vehicle theft deterrent (VTD) system and the content theft deterrent (CTD) system. The IPC receives a message from the theft deterrent control module or the rear integration module (RIM) via the serial data circuit requesting illumination.
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The VTD system requests the IPC to illuminate the indicator only when the ignition switch is ON. The VTD system uses the indicator as a malfunction indicator. For specific VTD condition that will illuminate the security indicator, refer to Vehicle Theft Deterrent (VTD) Description and Operation .

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The CTD system requests the IPC to illuminate the indicator only when the ignition switch is OFF. The CTD system uses the indicator in order to identify system status. For specific CTD condition that will illuminate the security indicator, refer to Content Theft Deterrent (CTD) Description and Operation .

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The IPC performs the displays test at the start of each ignition cycle. The indicator illuminates for approximately 3 seconds.
SERVICE THEFT SYSTEM The radio illuminates the SERVICE THEFT SYSTEM message when the VTD system detects a failure. The radio receives a message from the theft deterrent control module via the serial data circuit requesting illumination.
This is one you need to take to the dealer , unless you have a GM factory scan tool !

Where is the ignition switch at , on the steering column ? Did you transfer the theft deterrent control module from the old column to the new one ? Do you have any lights lit on the dash , SECURITY ? Your car has a anti-theft system , the key has a transponder pellet imbedded in the head of it . Behind the plastic cover of the steering column ,around the ignition lock cylinder is the theft deterrent control module an antenna !
The vehicle theft deterrent (VTD) system functions are provided by the theft deterrent control module. The VTD system prevents vehicle operation if a valid (learned) transponder PASS-Key?®III (PK3) ignition key is not used to start the vehicle. The theft deterrent control module has an exciter that is part of the theft deterrent control module as an assembly. The PK3 key has a transponder embedded in the plastic head of the key. The exciter is an antenna which is made up of wire coils which surround the ignition lock cylinder. The PCM enables the engines starter and fuel delivery system when it receives a valid (learned) password from the theft deterrent control module via the class 2 serial data circuit. The components of the VTD system are as follows:

Hello and welcome to FixYa!
I believe that he tripped the BCM (body control module). If the BCM is faulty, you can expect electrical failures on your vehicle for the electrical circuitry runs through the BCM. You may need to have it replaced to resolve the electrical issues.
Hope this helps and thank you for using FixYa! Have a good one!

Your vehicle is equipped with the Passlock theft-deterrent system.
Passlock is a passive theft-deterrent systemT. he system is armed once the keyi s removed from the ignition. Passlock enables fuel if the ignition lock cylinderi s turned with a valid key. If a correct key is not used, fuel is disabled.

During normal operation, the THEFT SYSTEM light will go off after the engine is started. Ln the unlikely event that the engine stalls and the THEFT SYSTEM light flashes, wait until the light stopsf lashing before trying to restart the engine. Remember to release thkee y from the START position as soon as the engine starts. If after several tries the vehicle still does not start, the vehicle may need service. At this time, you may also want to check the fuses. See your Pontiac dealer for service.

If the THEFT SYSTEM light comes on while the engine is running, a problem has been detected and the system may need service. See your dealer for service. In an emergency, call the Pontiac Roadside Assistance Program at 1 -800-ROADSIDE or 1-800-762-3743.

This ans other details can find it in this link for 1996 Pontiac Sunfire - Owners Manual.

I hope helps (remember to rate and comment this).

ANTI-THEFT SYSTEM Passive anti-theft system
Your ignition key has a unique imbedded transponder which engages engine electronics and allows the vehicle to be started. Without the use of your special ignition key, the vehicle will not start.

During each vehicle start, the coded key is read by the anti-theft system. If the key’s ID code matches the code in the anti-theft system, the vehicle is enabled to start.

Anti-theft system
Briefly illuminates when the ignition is turned to the ON position to verify that the passive anti-theft system is operating properly.

Also, its possisble that tou have actovated the fuel pump switch.

CHeck it.

theft protection rsets itself. I have never seen a PCM go bad. Some just need a reflash which costs much, much less. You can get a used PCM if you really think you need one, at car-part.com. Page with asterisk is lowest price.

here's some info on antitheft. What's your red light doing on the dash when you turn on the key or try to start the car?

The passive anti-theft system (PATS) also contains the following components:

• Theft indicator.
• Encoded ignition key.
• Passive anti-theft transceiver module.
• Hybrid electronic cluster (HEC).
• Powertrain control module.
• J1850 communication network.
• Lighting control module (LCM).

The passive anti-theft system (PATS) uses radio frequency identification technology to deter a driveaway theft. Passive means that it does not require any activity from the user. This system is known as SecuriLock® in North America, Safeguard® in the U.K., and PATS in Continental Europe. This information can be found in customer literature such as the Owner's Manual.
PATS uses a specially encoded ignition key. Each encoded ignition key contains a permanently installed electronic device called a transponder. Each transponder contains a unique electronic identification code out of over 72 million billion combinations.
Each encoded ignition key must be programmed into a vehicle's hybrid electronic cluster (HEC) before it can be used to start the engine. There are special diagnostic service procedures outlined in the workshop manual that must be performed if the encoded ignition keys need to be replaced.
The encoded key is larger than a traditional ignition key. The key does not require batteries and should last the life of the vehicle.
The transceiver module communicates with the encoded ignition key. This module is located behind the steering column shroud, and contains an antenna connected to a small electronic module. During each vehicle start sequence, the transceiver module reads the encoded ignition key identification code and sends the data to the HEC.
The control functions are contained in the HEC. This module performs all of the PATS functions, such as receiving the identification code from the encoded ignition key and controlling engine enable. The HEC initiates the key interrogation sequence when the vehicle ignition switch is turned to RUN or START.
PATS uses the powertrain control module (PCM) to enable or disable the engine. The HEC communicates with PCM over the J1850 network in order to enable engine operation. The HEC and the PCM use sophisticated messages in order to prevent a theft. The HEC communicates with the lighting control module (LCM), which controls the theft indicator.The HEC and the PCM share security data when first installed together that makes them a matched pair. After this security data sharing, these modules will not function in other vehicles. The shared PCM ID is remembered even if the battery is disconnected. The HEC also stores the vehicle's key identification code even if the battery is disconnected. There are special diagnostic workshop procedures outlined in this service manual that may be performed if either the HEC or the PCM needs replacement.
All elements of PATS must be functional before the engine is allowed to start. If any of the components are not working properly, the vehicle will not start.
PATS uses a visual theft indicator. This indicator will prove out for three seconds when the ignition switch is turned to RUN or START under normal operation. If there is a PATS problem, this indictor will either flash rapidly or glow steadily (more than three seconds) when the ignition switch is turned to RUN or START. PATS also "blips" the theft indicator every two seconds at ignition OFF to act as a visual theft deterrent.
PATS differs from the perimeter anti-theft system in that PATS enables and disables the engine from starting. If equipped, the perimeter anti-theft system protects the perimeter of the vehicle (doors, hood, and trunk) and sounds an alarm.