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ASEMaster35yrs, Chevy Technician
Category: Chevy
Satisfied Customers: 2095
Experience:  ASE Certified since 1972,Master Auto tech,Heavy Truck Tech ,chev dealer tech
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hello the security light is on in my 1999 chevy silverado my

Customer Question

hello the security light is on in my 1999 chevy silverado my truck will fire but shut off like a second latter we tried turn key on sit 11 min the try to start fired then shut right off then tried on 11min off back on 11 off back on 11 more then off to start same thing fire then shut down please help thank you
Submitted: 6 years ago.
Category: Chevy
Expert:  ASEMaster35yrs replied 6 years ago.

Hi, glad to be of help. This is definitely a passlock problem. You may need a new key lock cylinder or possibly a security module.

Try a 30 minute key relearn procedure first.

Here is the procedure for key relearn:


Theft deterent systems, relearn procedures


Passlock III Relearn Procedure

30-Minute Relearn Procedure

Use this procedure after replacing any of the following components:

  • The PASS-Key III plus keys
  • The theft deterrent module (TDM)
  • The powertrain control module (PCM)

This procedure is not available on vehicles equipped with EXPORT configured TDMs.

  • When performing the 30-minute relearn procedure, all previously learned keys will be erased from the TDM memory. Additional keys may be learned after performing the relearn procedure.

When replacing a TDM with a GM SPO Replacement Part, ensure the procedure to setup a new TDM is performed prior to the 30-Minute Relearn Procedure.

1. With a master vehicle key, turn ON the ignition, with the engine OFF.

2. Observe the security indicator. After approximately 10 minutes, the telltale will turn OFF.

3. Turn OFF the ignition, and wait 5 seconds.

4. Repeat steps 1-3 two more times for a total of 3 cycles or 30 minutes.

5. ignition OFF before attempting to start the vehicle.

6. With a master vehicle key, start the vehicle. The vehicle has now learned the key transponder information and/or the ECM has now learned the fuel continue password.

7. If additional keys are required to be learned, continue to step 7.

8. With a previously learned master key, turn ON the ignition, with the engine OFF.

9. Turn OFF the ignition and remove the key.

10. Within 10 seconds insert the key to be learned. Turn ON the ignition with the engine OFF. The vehicle has now learned the new key.


Here is some links and information to by pass the security system:


How to Bypass Passlock 2

Best solution


Build your own instructions $37


Buy outright $179


The easiest way would be measure your resistance and simply put the same value resistor between your orange/black and engine side yellow, tape the yellow coming from the key side. Must be sure to be within aprox 5% of the measured value or it could cause car to fail to start with the key or the autostart.

When testing PkII you need to test the "key side" of the yellow wire not the engine side or non key side of the wire that you cut. The resistance is coming down for the key cylinder.


The best way to bypass passlock 2

There is three wires going to your key switch one is black one is yellow and the other is orange or white cut the yellow in half and strip back the black wire ,take the yellow wire from key switch side and wrap the wire through and around the black and that should get you started