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Immoblizer

Tiny
KISHA8223
  • MEMBER
  • 1999 LEXUS GS 300
  • 6 CYL
  • FWD
  • AUTOMATIC
  • 206,000 MILES
Had coil replace because car didnt reconize the keys so the security light would blink and car want crank. But it worked for a few hours after replacing it until the alarm went off and it went back to not starting. Keys want lock doors, have to unpluge battery to get it to start. What could cause this to happen?
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Tuesday, August 9th, 2011 AT 11:16 PM

8 Replies

Tiny
KHLOW2008
  • MECHANIC
  • 41,815 POSTS
The coils should not be the cause for the keys not being recognised by the immobilizer or security system.

The keys not locking the doors means the door switch could be bad and unlocking the key does dot disarm the security system.

Did the alarm go off by itself or while you were attempting to open the door or start the vehicle?
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Tuesday, August 9th, 2011 AT 11:35 PM
Tiny
KISHA8223
  • MEMBER
  • 9 POSTS
Not sure u got my reply, the alarm went off when I was testing the locks because they where back working since they replace the coil. And I locked it and set it ooff by trying to open door fthru the window. Since then car don't rconize key car want crank only if I unplug the battery it will crank then
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Wednesday, August 10th, 2011 AT 1:09 AM
Tiny
KHLOW2008
  • MECHANIC
  • 41,815 POSTS
Have yu tried to lock and unlock the door with the key?

Try using the passenger door or trunk lid.

The driver door lock switch could be bad and does not unlock the door. Under such circumstances when you open the window to unlock, it is deemed forced entry and this would trigger the alarm/security system.
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Wednesday, August 10th, 2011 AT 11:41 AM
Tiny
KISHA8223
  • MEMBER
  • 9 POSTS
Im not so worry about the doors locking what im trying to worry about is why it want crank. The immoblizer light thats on the car doesnt go off when I put the key in it and its the master key. Ive tried both keys. On the Toyota rect it has replaced the TRANS COIL, but this didnt work for long it worked for about 3 hrs and the car went back to not starting only if I unplug one side of the battery then the car will crank. Should I take this car to the Lexus dealer maybe they have better knoledge of the problem because the Toyota people keeps charging me to fix somthing and its not it.
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Wednesday, August 10th, 2011 AT 12:43 PM
Tiny
KHLOW2008
  • MECHANIC
  • 41,815 POSTS
When the alarm system is breached, it can trigger the immobilizer and prevent starting even though you have the master key. You need to disalrm the security system to enable the immobilizer to work.

Since the problem is preventing starting, the key transponder might not be very reliable and reprogramming the key might solve the problem. Toyota and Lexus are supposed to be similar but then again where experience is concerned, I would rather go to the Lexus dealer.
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Wednesday, August 10th, 2011 AT 1:05 PM
Tiny
KISHA8223
  • MEMBER
  • 9 POSTS
Thank you! This I understand not what they been telling me. So reprogram the key would be the first thing I need to do? Thanks again and if I can donate money now can I do it?
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Wednesday, August 10th, 2011 AT 1:16 PM
Tiny
KHLOW2008
  • MECHANIC
  • 41,815 POSTS
Yes, since the key is intermittently not being recognised by the immobilizer, reprogramming the keys should be the first thing to do as both sets of keys have the same problem.

Prior to reprogeaming the keys, recheck the wiring and power supply to the immobiulizer ans security system. Any disruption can cause the problem as well. One thing that you need to look at would be the door locking system. If the keys do not work on all dors, you definitely have a fault with the power supply or security system. If it is only specific doors, then the problem would be the door switch.

Thank you for the offer of a donation but sorry to say I am not able to explain it to you as the system upgrade to our site is extensive and I seem to have lost track of quite a lot of things. Anyway I have contacted our admin and someone else would be answer to you shortly.

Keep me updated of how it goes.
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Wednesday, August 10th, 2011 AT 7:57 PM
Tiny
THIS IS MIKE
  • MECHANIC
  • 686 POSTS
Hi KISHA8223,
You can donate by asking another question and choosing to donate at that time. You can just thank the technician that helped you instead of asking another question unless you have another one. We will have another donation option button up soon to remedy this work around. Have a great day.
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Wednesday, August 10th, 2011 AT 8:59 PM

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