LAUNCH X-431 PAD III User Manual
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learning for the car. After tooth learning is successful, the MIL turns off.
After the engine ECU, crankshaft position sensor, or crankshaft flywheel is
replaced, or the DTC 'tooth not learned' is present, tooth learning must be
performed.
6.7 IMMO Service
An immobilizer is an anti-theft mechanism that prevents a vehicle’s engine from
starting unless the correct ignition key or other device is present. Most new
vehicles have an immobilizer as standard equipment. An important advantage of
this system is that it doesn’t require the car owner to activate it since it operates
automatically. An immobilizer is considered as providing much more effective
anti-theft protection than an audible alarm alone.
As an anti-theft device, an immobilizer disables one of the systems needed to
start a car’s engine, usually the ignition or the fuel supply. This is accomplished
by radio frequency identification between a transponder in the ignition key and a
device called a radio frequency reader in the steering column. When the key is
placed in the ignition, the transponder sends a signal with a unique identification
code to the reader, which relays it to a receiver in the vehicle’s computer control
module. If the code is correct, the computer allows the fuel supply and ignition
systems to operate and start the car. If the code is incorrect or absent, the
computer disables the system, and the car will be unable to start until the correct
key is placed in the ignition.
To prevent the car being used by unauthorized keys, the anti-theft key matching
function must be performed so that the immobilizer control system on the car
identifies and authorizes remote control keys to normally use the car.
When the ignition switch key, ignition switch, combined instrument panel, ECU,
BCM, or remote control battery is replaced, anti-theft key matching must be
performed.
6.8 Injector Coding
Write injector actual code or rewrite code in the ECU to the injector code of the
corresponding cylinder so as to more accurately control or correct cylinder
injection quantity.
After the ECU or injector is replaced, injector code of each cylinder must be
confirmed or re-coded so that the cylinder can better identify injectors to
accurately control fuel injection.
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