My 2003 chevy tahoe wont start the security light is on a friend said it probly the pass key but i bought the car used and there is no resistor on my key it has worked fine for a year now it wont start and the light is on how do i fix it

The fuel pump isn't being shut down , the engine computer isn't seeing a anti-theft system pass word (code) so it disables the fuel injectors . The security light on ? DTC'S - diagnostic trouble code's are stored . Need a factory or professional scanner to read this code's . You could try a by pass of the key an lock cylinder ,but that may not be the problem . Does your key have a resistor pellet on the side of the key >
GM VATS Key Resistor Key Security Bypass

By pass the VATS system . Has pellet on the key ? That's a resistor , measure with a ohm meter . Go to radio shack an buy a resistor of equal resistance . Find the wires under steering coulmn an solder the resistor in place . Videos on youtube showing how to do it . Or you can have it towed to a repair shop an have it fixed that way .

Sounds like anti theft problem. Make sure you are using factory key

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.

if the security light is on in the dash it wont crank or start it is a anti-theft lock up and is probly the wires that go from the key cylinder to thebody controler that are broke you need the change the lock cylinder and get new pass keys for it

does it have the v.a.t.s. system...a chip in the key? sometimes the little resistor in the key goes bad..if you have a spare key try it

Your vehicle is equipped with the PASS-Key II (Personalized Automotive Security System) theft-deterrent system.
PASS-Key II is a passive theft-deterrent system. It works when you insert or remove the key from the ignition.
PASS-Key II uses a resistor pellet in the ignition key that matches a decoder in your vehicle. When the PASS-Key II system senses that someone is using the wrong key, it shuts down the vehicle's starter and fuel systems. For about three minutes, the starter won't
work and fuel won't go to the engine. If someone tries to start your vehicle again or uses another key during this time, the vehicle will not start. This discourages someone from randomly trying different keys with different resistor pellets in an attempt to make a match.

The ignition key must be clean and dry before it's inserted in the ignition or the engine may not start. If the engine does not start and the SECURITY light stays on when you try to start the vehicle, the key may be dirty or wet. Turn the ignition off.

Clean and dry the key. Wait about three minutes and try again. The SECURITY light may remain on during this time. If the starter still won't work, and the key appears to be clean and dry, wait about three minutes and try another ignition key. At this time, you may also want to check the fuses (see "Fuses and Circuit Breakers" in the Index). If the starter won't work with the other key, your vehicle needs service. If your vehicle does start, the first ignition key may be faulty. See your dealer or a locksmith who can service the PASS-Key II.

If you accidentally use a key that has a damaged or missing resistor pellet, the starter won't work. The SECURITY light will flash. But you don't have to wait three minutes before trying another ignition key.

See your dealer or a locksmith who can service the PASS-Key II to have a new key made.

If you're ever driving and the SECURITY light comes on and stays on, you will be able to restart your engine if you turn it off. Your PASS-Key II system, however, is not working properly and must be serviced by your dealer. Your vehicle is not protected by the PASS-Key II system. If you lose or damage a PASS-Key II ignition key, see your dealer or a locksmith who can service PASS-Key II to have a new key made. In an emergency, call the Chevrolet Roadside Assistance Center at 1-800-CHEV-USA or 1-800-243-8872 (In Canada call 1-800-268-6800).

Also this could helpfull: 2000 Chevrolet Camaro - Owners Manual

Hope helps.

Your Passlock may need to relearn the ignition keys, if the ignition lock has gone bad like my in-laws Grand Am Gt, here is what i did so they will not get stranded any more. Buy a Passlock by pass module for around $70.00. You can orderone from GMPASSLOCK.COM in the mean time try resetting the Passlock. Good luck

Ignition keys relearn takes about 30 min to do. 30-Minute Learn Procedure 1. Turn ON the ignition, with the engine OFF. 2. Attempt to start the engine, then release the key to ON; the vehicle will not start. 3. Observe the SECURITY tell tale light. After approximately 10 minutes, the light will turn OFF. 4. Turn OFF the ignition switch, and wait 5 seconds. 5. Repeat steps 1 through 4 - two more times - for a total of 3 cycles of 10 minutes. 3x10 = 30 minutes. The vehicle is now ready to relearn the Passlock Sensor Data Code and/or passwords on the next ignition switch turn from OFF to CRANK Important: Turn the Ignition Switch OFF. The vehicle learns the Passlock Sensor Data Code and/or password on the next ignition switch transition from OFF to CRANK. You must turn the ignition OFF before attempting to start the vehicle. 6. Start the engine. The vehicle has now learned the Passlock Sensor Data Code and/or password. 7. With a scan tool, clear any DTCs if needed. History DTCs will self clear after 100 ignition cycles. Without a scan tool you may have momentary starter interruptions while history clears itself.

If it's the same as the VATS system in my 86 Corvette (resistor pellet in key) the ignition switch might need to be replaced. The contacts on the key wore low, replacing the key helped for a short time but the new contacts wore the switch down faster then it too needed to be replaced. $200!

as long as all the fuses are good.. its probably the blower resistor/module... located next to the blower motor under the pass. side of the dash..