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Gary
Gary, Chevy Technician
Category: Chevy
Satisfied Customers: 15914
Experience:  15 years GM master tech
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I have a 1999 Chevy Tahoe the security light is on it cranks

Customer Question

I have a 1999 Chevy Tahoe the security light is on it cranks up but cuts back off my key doesn't have a chip in it
Submitted: 1 year ago.
Category: Chevy
Expert:  Gary replied 1 year ago.

I am sorry your having this problem

99 % of these with the security lights on are an issue with the pass lock sensor that is built into the outer ignition lock housing case bad and not reading the key correctly

the key itself has a resistance reading built into the head of the key that the sensor reads when the key is put in the ignition lock cylinder

unfortunately the only fix for this other than sending the engine computer out to have the security system programming removed from it is to replace the outer ignition lock case that has the pass lock sensor built into it

you can try the relearn procedure i will list below to see if it will run for you so you can get it into the shop to be fixed

you can always get me back through this post for FREE anytime with any follow up with this question even after you rate us here at Justanswer as i do not get credit for my work until you rate us here

  1. Momentarily rotate the ignition key to the CRANK position (Do NOT start the vehicle), then release it to the RUN position (Do NOT key OFF in the process).
  2. Wait 10 minutes. Observe the SECURITY indicator. Refer to the following list for the appropriate responses:
    • If the passlock sensor was replaced the SECURITY indicator will flash for the 10 minutes duration.
    • If the EVO/passlock module was replaced, the SECURITY indicator will flash for a few seconds and then remain ON for the remainder of the 10 minutes duration.
    • If the VCM/PCM was replaced with a new programmed VCM/PCM and connected to the vehicle for the first time, the vehicle will start and this procedure may not be necessary.
    • If the replacement VCM/PCM was connected to any vehicle at any other time, even momentarily, the SECURITY indicator will flash for a few seconds and then remain ON for the 10 minutes duration.
  1. The SECURITY indicator will transition from flashing to ON briefly to OFF after 10 minutes if remaining in the ignition ON position.
  2. Turn the ignition switch to the OFF position and wait for 10 seconds.
  3. Repeat steps 3�6 two more times. The new security code is ready to be communicated among the Passlock sensor, EVO/Passlock module and VCM/PCM. The new password ***** ***** on the next ignition lock cylinder cycle from OFF to CRANK to ON (start attempt).