I have 2000 Chevy Tahoe Z71. The security light stays on

Hello. Yes, your Chevrolet's security system will 'shut-down' the ignition system; causing your truck to start but stop instantly. The truck 'thinks' it is being 'stolen' and will 'enable' it's security system to 'hamper' stealing it. Good luck and keep me informed; if you want to.

if the security light stays on and is not blinking when the key is turned on , (but do not try to start the car). then you can do a key computor. communication .turn key on and off and[ on ]leave it on for exzactly 10 minutes.the security light will turn off, now take key back to off and now start the car.

Just for the record, its a throttle body not a carb.
Sounds like the injectors are not getting power or a ground signal from the computer.
You would check them with a meter or low voltage test light.

Have you looked to see if the bulbs need to be changed , if you have it might be a blown fuse or the wiring could be messed up

Park lamp relay contacts maybe stuck closed .
Body Wiring Harness Junction Block
Under the left side of the instrument panel near the left kick panel

if leaking up around where torque -convertor maybe freeze plug it has 3 plugs behind flywheel/ if not there up higher can be intake -headgasket . i pretty sure its plugs

check for power at compressor to eliminate it,if you have power at plug the compressor is bad,then you need to make sure the system if full of freon,it won't kick it will low freon

I have had the EXACT same problem with my 03 Chevy Tahoe!!! I have yet to find out the solution!? I cleaned all my grounds and changed my rear speed sensor along with bench tested my alternator! Have you found the problem? I would be very grateful if you could hit me back with an answer!! Thanks

have someone tap on gas tank while you cranking it,,if it comes and goes while they do it ,, you need fuel pump

have alternator and battery check.