Key copying... With complications...

[nads1978]

My friend recently acquired an early V6 converted MK3.

The ignition barrel immobiliser ring is behind the passenger seat, with the (V6) ECU and an old key taped to it! Presumably the key is paired to the immobiliser.

There is only 1 (black) key with the car, it starts the engine & the remote unlocks the car.

If we buy a replacement key, and try to pair it ourselves, would the immobiliser & other key taped to it cause an issue?

What we want to achieve: a spare key with remote button functionality. No immobiliser reprogramming. - can a new key be copied from the working one?

[fawtytoo]

I'm guessing the key you use to start and lock/unlock the car with has nothing to do with the immobiliser. In which case, there's no need to pair it as the key taped to the immobiliser ring is doing that job instead.

EDIT: Scratch that. What car donated the engine? Have they used the ignition barrel from it? Do the keys look the same, that is, would they both fit ignition barrel and door locks? Then you'd be pairing it.

[nads1978]

Hi, engine is a 1MZ from a Camry, the ignition barrel is MR2, but the imobiliser ring from around it is adjacent to the ECU from the Camry, which is behind the passenger seat. The key looks similar, but has no blade, yes the immobiliser has nothing to do with the key I use to start & unlock. I need a 2nd (spare) key to start and unlock (with remote buttons), but not the immobiliser.

If I do the "foot dance" to add a key, I'm not sure what will happen - I don't want to make my only key unusable!

I suppose I'm asking how to get a 2nd remote functioning, as the key is easily cut - can the remote be cloned or added someway without immobiliser being affected?

Or, am I overthinking it, is the Camry ECU/immobiliser safe from being unpaired from the taped key?

[bobo83]

My understanding of the MR2 electronic system is that the ECU immobiliser and the remote locking are two separate systems. 

The ECU (immobiliser) uses a small capsule integrated into the key that is read by the ignition barrel immobiliser ring.

The remote locking system uses the small electronic board that has a battery found in the key. This is handled by a different electronic unit, not the engine ECU.

If my assumptions are correct, then the standard MR2 procedure of pairing a new remote locking key should work. To be safe, I would remove the tapped key from the car but I don't think it would matter.

[paulj]

The other key shouldn't cause an issue.  As others have said, the immobiliser and the remote/alarm are different systems.  I think you have the immobiliser "sorted" with the taped old key.  As for the alarm system you can code up to 4x keys to the ECU with the last 4 staying in memory - if you code a 5th key it will only be the very first which is lost and that is unlikely to be the one you have.  Even if it is, just code it back onto the ECU.

The key dance is in the how to guides but I do wonder if you might need a Camry key dance to talk to your Camry ECU.  When getting a replacement key bear in mind that Toyota used at least three types of remote control electronics. MR2 ones are tokai rika but there are also models that used Denso and another name that escapes me.  Tokai rika tend to have a grey insert in the key, do an image search.  If the innards of your existing working remote are not grey you might have to follow that lead...