aftermarket immobilizer bypass

[grumblefish]

Morning, all. I am newbie to the forum. My husband has a '91 FJ80, and we just picked up an '01 LX470 last weekend. The LX only came with one key (mechanical, no fob buttons), so I've been researching options for keys that don't involve a Lexus dealer. In trying to determine if I have a master or a valet key, I realized that the "security" light near the clock never comes on at all. At first I thought maybe the bulb was just out, but there is a plastic key shaped thing hanging from the A pillar on the driver's side, and I wondered if it was some kind of aftermarket security or remote start. Lo and behold, there is a box under the kickpanel labeled TBXKEY. I've googled, I've searched this forum, and I'm having trouble finding much info about aftermarket bypass systems, other than that you need them to install aftermarket remote start or security systems. I did locate the manufacturer of the TBXKEY, and have sent them an email asking for info. Since I have no additional fob for remote start, I'd just as soon remove the bypass, but since I don't know exactly what is being bypassed here (is it just a bypass for the transponder in the key, or is it bypassing other systems and acting as an immobilizer on its own?) I'm hesitant to do so. I'd really just like to figure out the most cost effective way to get a second key, but in order to figure out if I have a master, I think I have to do something about this bypass. While I wait to see if the manufacturer responds, I figured I'd reach out to see if anyone here has dealt with a similar issue. Thanks!

 

[nitteo]

I had no master key and no fobs. I was locking and unlocking with the key manually. Finally, I did this:

No Master Key ECU Swap for Virginized ECU with Keys

 

[Trunk Monkey]

For a remote start you need to have the transponder. Some do this by hiding a key under the dash, or I guess there's what you found to send the transponder signal. Should be able to just unplug and be back to where you can check the security light. But, your remote start won't work.

 

[grumblefish]

For a remote start you need to have the transponder. Some do this by hiding a key under the dash, or I guess there's what you found to send the transponder signal. Should be able to just unplug and be back to where you can check the security light. But, your remote start won't work.

I don't have access to use the remote start as is, since I have no fob, so no loss there. Assuming I unplug and it reverts the system to "normal", I assume then I can use the key that is likely hidden in the box?

 

[BEG]

View attachment 2026713

Open up that black box. There's a 50% chance you'll find an OEM key in there.

 

[grumblefish]

Open up that black box. There's a 50% chance you'll find an OEM key in there.

No such luck. A broken off peice of what I assume is an old fob is in there. I disconnected the box. Still no security light, and the truck started right up.

 

[BEG]

No such luck. A broken off peice of what I assume is an old fob is in there. I disconnected the box. Still no security light, and the truck started right up.

Are you sure the RFID chip isn't in that broken off piece of fob? That'd be a pretty straightforward swap into a new key housing.

 

[grumblefish]

Are you sure the RFID chip isn't in that broken off piece of fob? That'd be a pretty straightforward swap into a new key housing.

I assume the chip is in there, yes. It is just a flat piece of plastic with some Lexus markings, broken on one end, and tucked into the housing with a piece of foam so it fits. So the chip can be taken out and put in a new key housing?

 

[BEG]

I assume the chip is in there, yes. It is just a flat piece of plastic with some Lexus markings, broken on one end, and tucked into the housing with a piece of foam so it fits. So the chip can be taken out and put in a new key housing?

Yup. If the fob that's in there doesn't have the remote section included (and you want a remote key), you'll probably have to buy a new complete key and break it open to replace the RFID chip. That would be a good time to get a YotaMD shell from @suprarx7nut

I buy my replacement keys from 1010keys on eBay. They have great service and make extra sure they're cutting your keys correctly. If you need the shell only (you have the remote section with the buttons) then get these cut:

2 (BLADE CUT by PHOTO) REMOTE FOB KEY/SHELLS for LEXUS to REPAIR KEYLESS ENTRY | eBay

(2) FREE (PRE-CUT by PHOTO) KEYS REPAIR your SPARE / BROKEN 3 BUT REMOTE FOB KEY for LEXUS. ( DON'T EVER BUY AN UNCUT KEY! No need to find a Locksmith or go to your dealer for blade cutting. PHOTO INSTRUCTIONS… Take good clear digital photos of your existing key blade using most any “smart”...

www.ebay.com

If you need the remote section of the key, go with these (they'll verify the correct chip and blade type):

(BLADE CUT INC) DIY REMOTE ENTRY FOB KEY w/4C CHIP EASY PROGRAM KEYS for LEXUS | eBay

DIY PRE-CUT EASY TO PROGRAM 3 BUTTON FOB REMOTE KEY w/4C CHIP for LEXUS. Do It Yourself Programming is possible for the Lexus models listed in the compatibility chart provided your existing key is a MASTER KEY.

www.ebay.com

 

[grumblefish]

@BEG , excellent info. Thank you!!

This is what's inside the box... Literally a broken off piece of plastic under the copper coil.

 

[BEG]

@BEG , excellent info. Thank you!!

This is what's inside the box... Literally a broken off piece of plastic under the copper coil. View attachment 2027091

Wow, ok. Looks like they used a piece of the "flat key" and card that comes in the factory manual?

It looks like the transponder signal from the "credit card" is being amplified by the black box and basically tricking the immobilizer into thinking there's always a key near the ignition. I imagine if you take the chip out, or disconnect the box, the immobilizer should go back to functioning the way it's supposed to.

 

[Mauser]

Wow, ok. Looks like they used a piece of the "flat key" and card that comes in the factory manual?

It looks like the transponder signal from the "credit card" is being amplified by the black box and basically tricking the immobilizer into thinking there's always a key near the ignition. I imagine if you take the chip out, or disconnect the box, the immobilizer should go back to functioning the way it's supposed to.

It is the credit card key. That is just an amplifier for the transponder That chip should be in the ecu as a master. Just use it to program a new key.

 

[BEG]

It is the credit card key. That is just an amplifier for the transponder That chip should be in the ecu as a master. Just use it to program a new key.

That's good info. I wish mine had come with a credit card key. I wouldn't have had to solder in one of your chips!

 

[Mauser]

That's good info. I wish mine had come with a credit card key. I wouldn't have had to solder in one of your chips!

Haha. If mine would have had a master key I would have never figured out a cheap way to do it.

 

[grumblefish]

It is the credit card key. That is just an amplifier for the transponder That chip should be in the ecu as a master. Just use it to program a new key.

Thanks, @Mauser . Do I need to put the chip in a key, or can I leave it as it and go through the programming sequence with a new key?

 

[Mauser]

Thanks, @Mauser . Do I need to put the chip in a key, or can I leave it as it and go through the programming sequence with a new key?

I would just use it to delete all the keys and start over. Techstream is the easiest way to do it.

 

[grumblefish]

I would just use it to delete all the keys and start over. Techstream is the easiest way to do it.

Please excuse my ignorance and seemingly never ending questions. If I am going to delete my current key and start over, do I need to remove the tbx box and the fragment of the credit card key and start with virgin keys and the techstream? Or do I leave the fragment where it is and use the techstream to program additional keys?

I'd seen posts about the techstream prior to starting on this key quest, and realized early on that I probably would want one for a myriad of reasons.

 

[Mauser]

Please excuse my ignorance and seemingly never ending questions. If I am going to delete my current key and start over, do I need to remove the tbx box and the fragment of the credit card key and start with virgin keys and the techstream? Or do I leave the fragment where it is and use the techstream to program additional keys?

I'd seen posts about the techstream prior to starting on this key quest, and realized early on that I probably would want one for a myriad of reasons.

You will have to remove the box to program any keys because the amplified signal of that transponder will make the ecu think any key inserted is the transponder in the box.

You also can't check if your other key is a master because you don't have a working security light.

I would get rid of the box and check to see if your other key is a master. If it is use it to delete all the other keys and program new ones. If your other key isnt a master use your piece of card with a cut key shell with the electronics removed to program new keys.

You don't have to use Techstream to program the keys, but it makes it super easy. Techstream is the best tool I have bought for my Toyotas