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-   -   Master key won't start car (

tarzan17 07-31-14 02:47 PM

Master key won't start car
Hi guys,

I am trying to get my car started.

This morning the master key (I only have one key) shell broke off leaving the key in the ignition. Fortunately I had a pair of pliers in the car and was able to drive home.

At home I had an empty spare key (case and cut key - no electronics) I ordered from ebay. So I moved the electronics from the broken casing into the new one.

When I tried to use the new key to start the car, I can hear it turn over but not start.The lock/unlock buttons work on the key and the led is visible when I press them. New battery in key has not helped. Disconnecting the battery has not helped.

Any suggestions? Is the master key circuit board fried? I do have my master key code but only have one key. Is there a way to test whether the key is transmitting properly? Do I need to reprogram my master key?


AnthonyMtz 07-31-14 03:01 PM

Would definitely try the re-programing process I'm not sure but I think you need 2 keys

tarzan17 07-31-14 04:46 PM

Thanks. Still trying to figure what reprogramming to try.

Found this thread that talks about reprogramming remote entry. What the heck is remote entry? Is it the ECU or the key?

To program your remote entry:
Make sure no key in ignition, driver door open and another 3 doors are closed and locked.
Insert the master key into ignition switch then remove it. Lock and unlock driver door 5 times( use the lock and unlock buttom at the door handle, not the master switch).
Then close and open the driver door one time.
Lock and unlock driver door 5 more times (at the door handle, same like the second step).
Then insert the master key in ignition and turn it on and then off. Remove the key. You hear the door lock and unlock itself once.
Then press the lock and unlock bottoms on the key (at the same time) and hold it for about 3 seconds.
Release both bottoms and then just press the unlock bottom for about 3 seconds and you should be done with reprogramming the remote entry.

AnthonyMtz 07-31-14 05:03 PM

That programing is for the remote let's say the buttons on the remote stop working you have to reprogram them to the ECU I don't think the key Un - programed it's self from the vehicles anti theft system try this. Take the remote out of the key shell hold it against the ignition use the old needle nose pliers get the broken piece and see if it will start. Please let me know what happens :)

tarzan17 07-31-14 05:11 PM

Thanks. I tried using the two broken parts (key and electronics) earlier and it did not start the car as before. I'm thinking I may have damaged the electronics when I reinstalled into new shell.

With the doors locked, from outside of the window, I see that the "Security Light" is solid red. When I unlock the door with the key, the Security Light starts blinking. When I put the key into the remote, the Security Light stays blinking. I never paid attention to the light, but from what I'm reading it should go out if the ignition detects the key as master. I'm going to keep searching the web to see if I can find an answer.

tarzan17 07-31-14 05:19 PM

Tried to disable the flashing "Security Light" from this thread:

but it did not work when I tried the insert for 5 second then lock car using key.

I did discover an Easter Egg feature I never knew about though - if you lock the door with key AND hold the key in locked position, it will close all four power windows. Same is true if you open the door with key AND hold the key in open position, it will open all four power windows.

AnthonyMtz 07-31-14 05:26 PM

Yes pretty nice feature, do you have the master key card for the vehicle if so stick that by the ignition and try to start with key and It should start

AnthonyMtz 07-31-14 05:36 PM

Try this link out amd try the steps

tarzan17 07-31-14 05:38 PM

Unfortunately when I bought the car used, it did not come with the card. But I do have the keycode from when I ordered the spare keys online.

Do you know if the "Security Light" should go blank when I insert the master key?

From reading this thread, it might be a bad ECU?

I may call CAA and see if they can get it started.

tarzan17 07-31-14 05:43 PM


Originally Posted by AnthonyMtz (Post 8651081)
Try this link out amd try the steps

That looks like programming for a new master key with an existing master key. I only have the one key unfortunately.

AnthonyMtz 07-31-14 07:27 PM


Originally Posted by tarzan17 (Post 8651088)
That looks like programming for a new master key with an existing master key. I only have the one key unfortunately.

Yea I understand, at this point I would suggest you go to the dealer ship to have them look further into this also did you change the fob over to the broken housing and get the pliers and try to start it that way maybe the replacement key shell you purchased is not letting the signal through to the anti theft system swap every thing over to the broken one and try it that way

tarzan17 08-01-14 07:05 AM

Based on my reading, it looks like the ECU is not recognizing the key transponder chip and therefore not disabling the immobilizer.

Logically, either the ECU is bad or the key chip is bad. Because I was able to start the car with the broken key and drive home, the only change to the system was replacing the electronic from the bad key into the new key casing. The ECU was not changed in anyway that I know of. Therefore, I am assuming the key "lost" its programming or is bad.

My question: Because I only have one master key, can I reprogram a bad master key using the same bad master key? In other words, does the reprogrammed key get programmed from the ECU or from the master key?

Here are the facts I found:
- The chips inside every Lexus Key are “programmed” to a single vehicle.
- The immobiliser system searches electronically for a transponder chip when a key is instered into the ignition and turned.
- If the correct chip is present, the immo system will allow the Lexus vehicle to start. If the immo system fails to detect a chip the fuel supply to the engine is cut off.
- It is normally impossible to bypass, override or remove a Lexus immobiliser and still drive the vehicle.

My symptoms appear as if I have an incorrect replacement key:

- The transponder chip inside the replacement Car Key must be electronically “paired” to your Lexus vehicle so your new Lexus Car Key interacts as normal – working just like the manufacturer’s original key supplied to its first owner at point of original sale.
- If the Lexus key is programmed incorrectly, your replacement key will unlock the doors and turn in the ignition, but the car’s ECU (Engine Control Unit) will NOT allow the vehilce to start.

AnthonyMtz 08-01-14 09:25 AM

Ok I think I understand what you are saying now,unfortunately the cars ecu would have to be re-flashed to a new set of remotes i called up lexus and they said you can't reprogram any keys without the master key so basically the key card would have to be reprogramed as well with the ECU re-flashed and a new set of remotes luckily you don't have a 2001 (or do you) because their is no way to re-flash the ecu it would have to be replaced I looked up some info on this and some people bought a used ecu on ebay with the remotes and made like 5 other keys lol but in this is going to cost a pretty penny at the dealer....i heard of a one time lost key deal at the dealer that if you loose the keys and you need a new ecu they will give you the ecu but charge for the remotes, keys, cutting the key, labor , and reprograming costing upwards of 500+$ :(

tarzan17 08-01-14 10:29 AM

Thanks for your help. Will know shortly what is wrong - it's being inspected by Lexus tech right now.

AnthonyMtz 08-01-14 10:41 AM


Originally Posted by tarzan17 (Post 8651962)
Thanks for your help. Will know shortly what is wrong - it's being inspected by Lexus tech right now.

Great! I would live to hear about what they find and finally put this key programing mystery to rest lol

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