Immobilizer Help- Would a New Toyota Key from Dealer Fix the Issue? (1 Viewer)

[Recovering Rover]

2002 LC
250K Miles
Purchased used in August 2022
Only key that came with it is an after-market key that opens the doors and starts the car, but the fob will not work (it’s not programmed).

Ever since purchasing the LC. the immobilizer “seems” to get wonky if the car is open for too long (for example I leave it unlocked or I’m working on it with the doors open) or if I hit some unknown sequence of lock/unlock from the inside buttons.

But usually after I’ve entered the car and see the red anti-theft blinking, I place the key in the ignition and it goes off. Car starts fine.

If I enter the key and it’s still blinking, the immobilized kills the spark and it won’t start.

If so, I simply remove the key, lock all doors from the inside, manually unlock the driver’s door, shut it and manually lock it with the key by turning once to the left. Then, once I manually unlock the driver’s side door with the key by turning once to the right, the immobilizer almost always shuts off when I then put the key in the ignition.

Today was the first time I followed that sequence and it didn’t disengage. I tried the sequence once more after 5 minutes and it worked.

My question is: if I have my Toyota dealership order me a new key and program it, should that fix the issue? I don’t know if it’s related to the key being after-market and obviously not programmed for the fob to work.

Lastly, is there some way to simply disable the immobilizer/anti-theft? It’s much more of a hassle than it’s worth.

Cheers!

 

[kevgentile]

Programming the fob is an entirely separate function from the immobilizer circuit. You need to check for any faults in the circuit. You'll probably find that the problem is in the key antenna or amplifier.

 

[Recovering Rover]

Programming the fob is an entirely separate function from the immobilizer circuit. You need to check for any faults in the circuit. You'll probably find that the problem is in the key antenna or amplifier.

As in the after-market key that came with the vehicle?

For that reason I assume a key from Toyota that’s programmed to my car should resolve the issue, but that will cost around $600.

It’s worth it for the fix but I don’t want to buy a new key if it’s not going to cure the issue

 

[kevgentile]

As in the after-market key that came with the vehicle?

For that reason I assume a key from Toyota that’s programmed to my car should resolve the issue, but that will cost around $600.

It’s worth it for the fix but I don’t want to buy a new key if it’s not going to cure the issue

The fob is programmed to the wireless door lock ecu, not the actual immobilizer chip in the main ecm. The keys 4c chip internal to the key is coded to the immobilizer circuit thru a unique transponder serial number. Your immobilizer obviously has this coded since it starts the truck. 4C chipped keys either work or don't work so it's not very likely it's an intermittent key issue.
Again, find a way to scan the circuit to avoid throwing parts and keys at it. It's a basic circuit, a meter and the wiring diagram will get you where you need to go. You can download it from mud.

 

[kevgentile]

Also check to make sure you key unlock warning switch circuit is operating properly. Simple check is to turn the IG on, open the door, lock the door with the lock button and it should immediately unlock.

This ksw circuit does tie into the immob circuit though I haven't confirm that it would actually effect the key from shaking hands with the ecm/immob. But it's worth confirming operation.

Your erratic door lock behavior is probably due to a failing door lock ecu

 

[suprarx7nut]

2002 LC
250K Miles
Purchased used in August 2022
Only key that came with it is an after-market key that opens the doors and starts the car, but the fob will not work (it’s not programmed).

Ever since purchasing the LC. the immobilizer “seems” to get wonky if the car is open for too long (for example I leave it unlocked or I’m working on it with the doors open) or if I hit some unknown sequence of lock/unlock from the inside buttons.

But usually after I’ve entered the car and see the red anti-theft blinking, I place the key in the ignition and it goes off. Car starts fine.

If I enter the key and it’s still blinking, the immobilized kills the spark and it won’t start.

If so, I simply remove the key, lock all doors from the inside, manually unlock the driver’s door, shut it and manually lock it with the key by turning once to the left. Then, once I manually unlock the driver’s side door with the key by turning once to the right, the immobilizer almost always shuts off when I then put the key in the ignition.

Today was the first time I followed that sequence and it didn’t disengage. I tried the sequence once more after 5 minutes and it worked.

My question is: if I have my Toyota dealership order me a new key and program it, should that fix the issue? I don’t know if it’s related to the key being after-market and obviously not programmed for the fob to work.

Lastly, is there some way to simply disable the immobilizer/anti-theft? It’s much more of a hassle than it’s worth.

Cheers!

A couple thoughts:

1. Do you have anything else on your key chain or around the key? The immobilizer is rather sensitive so a poorly made aftermarket key with a radio-challenged chip could need a totally clear path to the ignition.
2. You can get a new key for ~$125. Get the part number and search online and even check ebay. I've had customers buy a YotaMD kit with a new blade from me and then get a good condition used remote on ebay and end up with a "new" master key that'll last for life for under $200 all in.
3. You cannot disable the immobilizer far as I know. It's a very effective anti-theft device. That's more valuable on a brand new $100k car (which these nearly were 15 years ago), but understandably annoying on a beat up old car now. Just get a good key and clear your keychain and it's a non-issue.

 

[magikaram]

You cannot disable the immobilizer far as I know. It's a very effective anti-theft device.

Not that you're wrong, I wholly believe you, but one of the previous owners to my LX has somehow bypassed the immobilizer. None of my keys are recognized by the ECU as the security light doesn't disable upon key insertion to the cylinder, which if the car were factory, it shouldn't start. I had a locksmith cut new keys, and without programming they started the car.

I'll be virginizing the eeprom soon, that way I can remove whatever garbage wiring someone put under the lower dash panel. If I figure out what the wiring or modules were installed, I can share.

 

[suprarx7nut]

Not that you're wrong, I wholly believe you, but one of the previous owners to my LX has somehow bypassed the immobilizer. None of my keys are recognized by the ECU as the security light doesn't disable upon key insertion to the cylinder, which if the car were factory, it shouldn't start. I had a locksmith cut new keys, and without programming they started the car.

I'll be virginizing the eeprom soon, that way I can remove whatever garbage wiring someone put under the lower dash panel. If I figure out what the wiring or modules were installed, I can share.

Master turns off red light.
Valet does not.

Both start the car.

Sounds like maybe someone shoved a valet remote up into the ignition bezel?

 

[magikaram]

Master turns off red light.
Valet does not.

Both start the car.

Sounds like maybe someone shoved a valet remote up into the ignition bezel?

I'll take a closer look at it this weekend, there is a remote start module connected to the system, so maybe someone used the valet/card key to get it to work?

 

[Trunk Monkey]

Almost definitely what happened, a remote start on these won't work without a immob. chip present, so the usual solution is to hide a key in the dash to fulfill that. Hopefully it's one that they cut the blade off so that if someone were creative and found it, they couldn't then start the truck.

 

[suprarx7nut]

I'll take a closer look at it this weekend, there is a remote start module connected to the system, so maybe someone used the valet/card key to get it to work?

That is exactly what happened. I'd bet a dollar.

 

[kevgentile]

A immob delete can be done, but like suprarx7nut said it's not really worth it since you'll still have to send the ecm out if you don't have the ability to read and write to the ic900 chip.

To delete requires a unique file written to the chip and you must clip one of the wires in the immob circuit. You're better off diag'ing the problem and correcting it properly.

The master keys extinguish the security light immediately upon insertion where as the valet will illuminate for 2 seconds and then extinguish the light. I have recently had spent many hours diag'ing a faulty system.

 

[magikaram]

so I've opened up the two modules that have spliced into presumably the immobilizer wiring. Neither had a valet/master key chip in them. One PCB had no branding, the other was an iDatalink ADS-TB... which when googled shows up as an immobilizer bypass/remote start kit for the LX470.

Still no clue what the first mystery box does, only name on it is 'CM-800'. I forgot to take a picture yesterday while I did the exploratory search with it.

As expected, without the 'kit' installed, my keys do not start the car. I'll need to pull the ECU and virginize the ic900 chip with a bit of kit that I snagged to read/write EEPROMs. Hopefully if I can get the chip reprogrammed, removing this kit wont block me from starting the car.