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john -aka eauto
john -aka eauto, The Car Guy
Category: Cadillac
Satisfied Customers: 15841
Experience:  15 years as a auto tech
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1996 sts: anti theft mode and will not start what can I do

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my 1996 sts seville goes into the anti theft mode and will not start what can I do

Ok its stuck in security mode

OK, there may be an issue with the security system, but lets try a relearn procedure. It is posted below. Try it an let me know what happens.

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.

    Important: The vehicle learns the key transponder information and/or passwords on the ignition switch transition from OFF to RUN. You must turn the ignition OFF before attempting to start the vehicle.

  5. 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.
  6. If additional keys are required to be learned, continue to step 7.
  7. With a previously learned master key, turn ON the ignition, with the engine OFF.
  8. Turn OFF the ignition and remove the key.
  9. 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.

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Customer: replied 7 years ago.
Thank you very much you save me alot money and headace sts seville has started again. my battery had went dead first thing this mornin i jump it off and reapplied what you had told me to do. and 1:30 10 -20- 2009 it works. thank again i am very pleased with you help. will recommend others to you and this site. after I did that process and let the car set for a couple of hrs it was good to go.


Customer: replied 7 years ago.
Hello john Aka eauto you help me out on the 1996 sts seville now it laped back to the same mode again I am so mad at this car, I don't know what to do. it does has 162000 miles on it what else to do. (anti security mode will not start what do you sugget
Most likley the ignition key switch or ignition key is faulty ....I would start by trying a different key if not it will most likley require key switch replacement