On 2003 Chevy Tahoe Z71, Content Theft Deterrent Light is flashing and vehicle cranks but then instantly shuts down. Fuel pump appears to shut process down. How can I turned this off/reset? Why did it come on in the first place? This happens every once in a while. Then just disappears for a while. Thank you!

fuel pump shut off due to security light on ????? Security systems do not disable fuel pumps , disables cranking and or fuel injectors . So what the service light isn't on ??? If the security light is lit codes are stored in the BCM - body control module ,theft deterrent module , What ever controls the theft system on your fantom vehicle . Your best bet ,have it towed to a qualified repair shop.

What alarm ? Content theft alarm ? Think's the vehicle is being broken into ? Something other then horn going off ? This is the factory alarm .

Content Theft Deterrent (CTD) System
The Content Theft Deterrent function provides the theft deterrent by sounding the horn and flashing the headlamps and the park lamps when there is an unauthorized vehicle entry or there is tampering detected.

Hello Narisol,


Excerpt from the 2003 Owners Manual.


Passlock

Your vehicle is equipped with the Passlock theft-deterrent
system. Passlock is a passive theft-deterrent system.
Passlock enables fuel if the ignition lock cylinder is turned with a valid key. If a correct key is not used or the ignition lock cylinder
is tampered with, the fuel system is disabled and the vehicle
will not start. During normal operation, he SECURITY light
will turn off approximately five seconds after the key is turned to
RUN. If the engine stalls and the SECURITY light flashes,
wait about 10 minutes until the light stops flashing before trying
to restart the engine. Remember to release the key from START as
soon as the engine starts. If the engine does not start after
three tries, the vehicle needs service. If the engine is running and the
SECURITY light comes on, you will be able to restart the engine
if you turn the engine off. However, your Passlock system is not
working properly and must be serviced by your dealer. Your vehicle is not protected by Passlock at this time. You may also want to
check the fuse. See Fuses and Circuit Breakers on page 5-85.
See your dealer for service. In an emergency, call the M
Roadside Assistance Center. See Roadside Assistance Program on
page 7-5.


Excerpt from the 2003 Owners Manual.

Testing the Alarm The alarm can be tested by following these steps:
1.
From inside the vehicle, Iower the driver's window and open
the driver's door.
2.
Activate the system by locking the doors with the power door
lock switch while the door is open, or with the remote keyless entry transmitter.
3.
Get out of the vehicle, close the door and wait for the SECURITY light to go out.
4.
Then reach in through the window, unlock the door with the manual
door lock and open the door. This should set off the alarm. When
the alarm is set the power door unlock switch is not operational.
If the alarm does not sound when it should but the headlamps flash, check to see if the horn works. The horn fuse may be blown. To
replace the fuse, see Fuses and Circuit Breakers on page 5-85.
If the alarm does not sound or the headlamps do not flash, the
vehicle should be serviced by your dealer.

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:
?€¢
The ignition key

?€¢
The column-mounted theft deterrent module with integrated antenna

?€¢
The transponder

?€¢
The engine control module (ECM

It almost sounds as if the vehicles theft deterrent system is shutting down. Is your vehicle equipped with a theft deterrent system ? If so there's several things that could be wrong or it could be as simple as doing what's called a relearn for that system. Attempt to restart it, once it starts then dies leave the ignition switch in the run position, if equipped with a theft system ( check your owners manual) there will be a light in the instrument panel that will begin flashing , while leaving the ignition switch in the run position wait for about 10 minutes, the light SHOULD stop flashing. Turn the ignition switch to the off position and attempt to start it. If it still bothers you're either dealing with something deeper or different type of a problem. Good luck.

Is the security light in the instrument panel ON of Flashing? If so the TDM (Theft Deterrent Module) will shutdown the fuel delivery.

Have you anti theft system checked, that is where your problem will be.

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Have it checked for DTC'S - diagnostic trouble code's . I suspect the problem is with the tdm module or the ignition switch ???? Assuming will only get you into trouble . If the PCM - engine computer does not see the right coded meassage from the TDM it won't turn on the fuel injectors or it will cut them off in two seconds . .
Buick Security Systems 1998 Chevy is the same .
Ignition Key With Wrong Resistor Pellet Code is Used To Start Engine
The theft deterrent module performs one of the two following actions when you attempt to start the vehicle with a wrong ignition key:
• There are 15 PASS-Key® II resistance ranges. The PASS-Key® II resistance may be one of the 14 valid but incorrect PASS-Key® II resistance ranges. The theft deterrent module will perform the following actions when you attempt to start the vehicle (if the condition is present during an engine start attempt or for 1 second any time after the engine has started):
• Turns on the SECURITY indicator
• Sends a password to the PCM through the fuel enable signal circuit
• The password disables fuel delivery to the engine.
• Disables the theft deterrent relay, which disables the starter circuit
• Disables sampling of the PASS-Key® II resistance for 3 minutes
• The 3 minute time period is called the shut-down period.
• Disconnecting the battery will not clear the timer sequence. The timer sequence will resume when battery power is restored.
• Inserting the proper key during the vehicle shut-down period will not start the engine. The engine will not start until the shut-down period has elapsed.
• After the shut-down period, the engine will start if the correct ignition key resistor pellet is used.
• The PASS-Key® II resistance may be correct and allow the engine to start. Later during the same ignition cycle, the PASS-Key® II resistance may be one of the 14 valid but incorrect resistance ranges. The theft deterrent module will perform the following actions:
• Enters the fail-enable mode
• Turns ON the SECURITY indicator
• Sends a password to the PCM through the fuel enable signal circuit when more attempts to start the engine occur
• The password allows the fuel enable circuit to deliver fuel to the engine.
• Enables the theft deterrent relay, which also enables the starter circuit.

Ignition Key With Correct Resistor Pellet Code is Used To Start Engine
The theft deterrent module performs the following actions when the correct ignition key is used in order to start the vehicle:
• Enables the theft deterrent relay. The theft deterrent relay enables the starter unit.
• Sends a password to the Powertrain Control Module (PCM) through the fuel enable signal circuit. As a result, the PCM allows fuel delivery to the engine.


By pass theft system .
GM VATS Key Resistor Key Security Bypass

Only if theft light is flashing, then it would need to be reset, to reset turn key to on and wait till theft light stops flashing about 10mim or so, then turn key to off and back to start engine.