The immobiliser system (from Steve, Jags on Gas - several posts August 2011 and December 2011)
The Immobiliser system elements are the key mounted chip, the security module mounted inside the NSR (LHS) wing, the exciter ring around the ignition barrel, the ECU (RHS kick panel) and all the wiring in between.
The chip in the key has no power of its own (batteries are not used in the key) so the chip must be powered up to reveal its code by EMF coming off the exciter ring, just like a chip placed under the skin of a pet Dog. The key chip has a unique and non-erasable code which is registered in the security module during set up.
If the chip is not registered to the security module (or the record has been lost) when an attempt to crank is made, the engine will be immobilised.
The immobiliser system is quite seperate to the key fob operated alarm system. Flat batteries in the key fob cannot result in loss of chip registration over minutes, days or weeks as the memory of the unique key / chip code is held within the security module. This module has a CMOS battery for memory retention although all can be lost if the car's battery is flat or disconected for very long (indeterminate) periods.
To find out if a car is immobilised, perform this check
Turn ignition on but do not crank the engine. Observe the orange 'check engine' light in the bottom left corner of the instrument pod. If that light goes out, the car is immobilsed, at least by the starter not cranking the engine if you try to start it.
The fact that other systems like wipers, lights, windows etc. will still work can confuse the issue. The fact that they are working means nothing at all. The engine alone is immobilised.
*Apparently cars built for the U.S. market do not have this immobiliser system.
The most important thing to understand by far is that the immobiliser operates (or does not operate) a disablement system within the ECU. Imagine it as simply switching a wire. The reason for my seperation of the two systems using two different labels is that the car's engine can be disabled even though the immobiliser system is working and the chip-in-key has been accepted.
Immobilisation = Disablement, although Disablement can occur without Immobilisation.
P1621 [0,8,16,21] please refer to the relev ant manual i to caly komunikat sam kod mowi jak sie nie myle oNiektórzy teraz pewnie się zaczną śmiać, bo za każdym razem gdy ktoś pisze o tym błędzie, to się pojawiam ja ze swoim czujnikiem położenia wału :-hehe
Engine control module engine immobilization input circuit malfunction