security light?

1999 MERCURY COUGAR
100,000 MILES • V6 • 2WD • AUTOMATIC
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PEGGY WHITE
  • MEMBER
  • 3 POSTS
Changed alternator and battery now car will not turn over. When key is turned dash lights and radio come on but no engine sound. Security light blinks until you turn key on to start then remains on. Is it the anti they system messing up? I do not have the original key I had to have one made.
Jul 10, 2018 at 6:09 AM
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ROL*S.
  • AUTOMOTIVE REPAIR CONTRIBUTOR
  • 61 POSTS
Hi Peggy,

Your car could have either of two different anti-theft systems. Active or Passive. The passive system disables the car to crank or start. I added an image that shows how the security blinks when there is a malfunction. Basically your key needs to be programmed. You might have a local shop that can do it but it is probably a dealer job.
Did that key start the car before the alternator and battery was replaced?
Image (Click to enlarge)
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Jul 14, 2018 at 12:05 PM
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PEGGY WHITE
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It is a passive system I do believe, but it also has a remote start anti theft. I do not have the original key or key fob to reset it. Had to have a locksmith make a key for it but it did start it prior to the alternator being replaced.
Dec 12, 2018 at 6:33 PM
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STRAILER
  • AUTOMOTIVE REPAIR CONTRIBUTOR
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Can you turn on the headlights then try to crank the engine over, have someone watch the lights to see if they go out when you crank the engine over. Please let me know, Ken
Dec 15, 2018 at 10:52 AM