Immobiliser problem

[Lynnec]

I left my key in the ignition turned on. The Battery went flat. I attached jump leads but the car won't start. I suspect the imobiliser is on. Can any one advise how to turn it off please

[Lynnec]

Surprised that not one person has replied to this request for help

[Parts-King]

The immobiliser cannot be turned off, I suspect you may have jump started it with the leads the wrong way round and popped a fuse. Check the main large fuses, usually 100/120 amps, and see if any are blown. You will need to sort that out before you will be able to start it 

 

[Lynnec]

I didn't put the leads on incorrectly. The engine turns over perfectly just won't fire up

[Parts-King]

I think you can discount an immobiliser problem, the keys are chipped and the engine ECU controls the immobiliser. You now need to do some basic checks, does it have fuel? does it have a spark at the plugs? that sort of thing......

[Lynnec]

It was running great until I left the key turned in the ignition. It's just had a full service last week

[Parts-King]

Back in the day it was possible to burn out the coil, but not in modern cars. I think you might need some assistance to check the basics, like i said, fuel, spark etc

[Gerg]

2 hours ago, Lynnec said:

Surprised that not one person has replied to this request for help

I don't think this is an unwillingness to help, just that there are no straightforward answers to your problem.

Having said that, if you have another key for the car, have you tried that one too?  Or are you using a key that is not the normal one since the Battery has gone flat?  I doubt that this is the problem, but as it is so easy to rule this out!

Just as background, the car is configured to work with the unique code of the immobiliser chip in the key fob (this is nothing to do with the key fob Battery and door lock remote control).  This immobiliser chip takes all its power via induction from a circuit next to the ignition key switch, in the same manner that wireless phone charging does.

So, in effect, the car is configured to the key(s) - that's as I understand it anyway.

The very few times that I have had what was basically this problem (not on Toyotas, as it happens), there has been an 'immobiliser warning' on the dash (actually shown in words of the radio display of a Peugeot I had with this) when an attempt was made to start the car.  I imagine that there is no fault indication on the dash in this case?

[Lynnec]

No although a couple of weeks before this the engine kept cutting out and the diagnostic said it was an immobiliser fault. I changed keys and it ran fine until the Battery went flat when I left the  ignition on

[Lynnec]

I've got the Battery on charge now so I'll see what happens when it's done. Thank you for your replies

[Parts-King]

I very much doubt there will be an immobiliser fault, very very rare, good luck in finding the fault  

[Lynnec]

Story  of my life. The rare and impossible always happens to me. The diagnostic showed 5 immobiliser faults and it cut out 5 times so who knows 😔

[Gerg]

21 hours ago, Lynnec said:

No although a couple of weeks before this the engine kept cutting out and the diagnostic said it was an immobiliser fault. I changed keys and it ran fine until the battery went flat when I left the  ignition on

I have no great insight into a problem like this (unlike Kingo, above, who , as you can see, works at a Toyota dealer).  But from what you've added above, I would imagine that:

The immobiliser receiver/transmitter module that lives immediately next to the mechanical ignition key lock (black module pictured under the red arrow in this picture from eBay, of an Avensis lock for sale), is slowly failing to 'energise' the ignition key itself, because the internal electronic inductive element is 'going down', so the immobiliser chip code is not being generated, as the 'wireless generation' function is failing to get enough power into the key.

So, I'm thinking that one key is marginally better (but still within the specification) at producing the code pattern at a reduced wireless power from the keyswitch module, this is the key you were using when the immobiliser module problem got worse, and both keys then stopped working, after your Battery went flat.

The other key is the 'weaker' key, and was failing whist you were actually driving the car.  But both keys, in this hypothetical scenario, are still good.

I think that the module shown with the arrow, either has a poor connection, or has failed.  Your leaving the ignition on is perhaps coincidence - this was going to happen anyway.

Re-seating the connection to this module is fairly easy as the access is straightforward (but I don't know the Avensis - never owned one).  So this is well worth trying first.  And the part itself, from a breakers, looks reasonably priced (the one shown was ~ £20).  The module arrowed just needs removing and fitting to your car to possibly fix the problem if it remains after its connector has been re-seated.  I think that there would be no special configuring required, and you can continue to use your old keys.  This could be finished in under an hour if there are no special security bolts to have to deal with (which there sometimes are around the steering column lock, but I can't see anything on the electronic module itself).

But, all the above is conjecture(!), and I would be happy to hear from someone who knows better!

Hopefully, you've got it sorted already....