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Lexus Immobilizer

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Old Jul 19, 2016 | 06:14 PM
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Default Lexus Immobilizer

My Lexus is still showing the solid red light, but only when the lock is initiated by 1 of the key fobs.
I've gone through the manual reset, and if I set the alarm and put either key fob 1, key fob 2, and valet key in ignition each time security is set, the security light goes out. So I'm guessing that all the keys are recognized. Have been unable to program the 2nd key fob, I don't know if I am doing something wrong, but I followed the directions and tried several times. Both fobs are functional, lights on fob work, battery power is there. I had accidentally tried to verify or reset the 1st fob the other day and the car responded with it locking and unlocking by itself. I erased the fob and then was able to put it back in again and it works... But not the second.
Tried inputting each key quickly, but the security light is still solid red.
The other day I was able to set off the alarm by locking all doors and reaching in to unlock through the open window, the alarm went off. That is no longer the case... The only thing that happens now is that once the door is unlocked the security light goes off.
I'm baffled. I'm 40+ miles from a Lexus dealership. I'm irritated. My brain hurts from reading all the mechanical documents on Diagnostics, Body Mechanical, etc, etc etc...
My multimeter scares me, because I just don't get it and I'm afraid I'm going to do something wrong. There is a connector in the rear that is unplugged and I don't know what it goes to, and no one will respond to my post.
On a happy note... I fixed the trunk door lock, I dismantled the antannae motor housing only to find out the computer was fried, but I found the pulley cord finally. I repaired the passenger tail light and resealed it and it looks great and works. I dismantled and cleaned and then replaced the entire cup holder console (boy was it dirty, especially the rear air flow compartment), I removed and replaced the engine air flow/filter assembly, understand how it all works, cleaned it and put it back in place. Finally found a great product to clean really yellowed headlights and they look new, detailed entire car, or, mats, etc and it looks great. But the damn immobilizer system or theft deterent system has me so upset.... AHHHH!
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Old Jul 19, 2016 | 06:18 PM
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Oh yeah... And I'm now a "Rookie" on Club Lexus!!! Who hoo!! Lol
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Old Jul 19, 2016 | 07:09 PM
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Is that unplugged harness in your back for the trailer wiring? I believe these are prewired. I couldnt fond anything in the shop manual.
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Old Jul 19, 2016 | 07:35 PM
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Originally Posted by Drcoffee
Is that unplugged harness in your back for the trailer wiring? I believe these are prewired. I couldnt fond anything in the shop manual.
I have no idea here are the pictures..




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Old Jul 19, 2016 | 09:29 PM
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Tail houses antenna, tail/trunk lights rear wiper, rear lock ... going on the limb .. remote receiver. Nothing to do with immobilizer.

Salim

Last edited by salimshah; Jul 19, 2016 at 09:32 PM.
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Old Jul 20, 2016 | 04:12 PM
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Update...
So today I hooked the ground back up to the battery and let it sit for awhile. Tried to reprogram the second key fob several times again, to no avail.
Noticed that all 3 keys will now set the alarm when using them in the drivers door lock. The security alarm only stays on solid red for about 30 seconds and then goes out. So I left it like that, windows down and then came back, reached into unlock it and boom, the alarm went off. Had to run and grab my key fob to stop it.
The other weird thing is that when I lock and unlock the doors with the valet key they cycle like 2 times now.
What does this mean???

Still baffled.
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Old Jul 20, 2016 | 04:13 PM
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Originally Posted by salimshah
Tail houses antenna, tail/trunk lights rear wiper, rear lock ... going on the limb .. remote receiver. Nothing to do with immobilizer.

Salim
What are the blue connectors for?
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Old Jul 20, 2016 | 04:26 PM
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Sorry .. I dont know.

Its been a while I had to remove the the antenna motor and I dont recall if it a blue dot.

Salim.
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Old Jul 20, 2016 | 04:30 PM
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Originally Posted by PrisyCrisy
Update...
So today I hooked the ground back up to the battery and let it sit for awhile. Tried to reprogram the second key fob several times again, to no avail.
Noticed that all 3 keys will now set the alarm when using them in the drivers door lock. The security alarm only stays on solid red for about 30 seconds and then goes out. So I left it like that, windows down and then came back, reached into unlock it and boom, the alarm went off. Had to run and grab my key fob to stop it.
The other weird thing is that when I lock and unlock the doors with the valet key they cycle like 2 times now.
What does this mean???

Still baffled.
Please do not mix the remote function with immobilizer function. The remote is based on RF signal to operate locks and windows. The immobilizer works on magnetic signature match. The magnetic signature is radiated by a slug (in the key) and ecu matches the signature against what was programmed in by master key.

Salim
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Old Jul 20, 2016 | 05:18 PM
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I believe those wires are likely for the optional navigation system. If I recall correctly, that's where the DVD drive for the navigation system would reside, if so equipped.
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Old Jul 20, 2016 | 05:30 PM
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Originally Posted by salimshah
Please do not mix the remote function with immobilizer function. The remote is based on RF signal to operate locks and windows. The immobilizer works on magnetic signature match. The magnetic signature is radiated by a slug (in the key) and ecu matches the signature against what was programmed in by master key.

Salim
I definitely get they are two different systems.
But the security light has to do with the theft deterrent system... Right?
The immobilizer relates to the keys, and the keys once put in the ignition turn off the security light, which means the keys are accepted... Correct?
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Old Jul 20, 2016 | 07:34 PM
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blinking red light goes off as I insert a master key (registered) in the ignition.

Salim
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Old Jul 21, 2016 | 05:30 AM
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Again..... My car only has a solid red light now...
Which seems like it's in a program mode.
It used to blink... But it's not right now
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Old Jul 21, 2016 | 06:59 AM
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I vaguely recall a process of inserting and removing in succession all master key in ignition. Not sure if it was accompanied by brake pedal action.

Salim
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Old Jul 21, 2016 | 09:13 AM
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Apparently there is a "break code" that can be used, but the only way to get it is to contact the Lexus Manufacturer or dealer and it must be requested through a Service Manager to release this security authorization. It is some type of code used in conjunction with brake pedal and turning of the master key.

Wish I could obtain this information and just do this myself !!!!!!
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