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● F_Try : The counter counting wrong PIN is entered.
Influence of the ignition on the PIN entry
From label "Start" to "PIN entered" action, any falling edge on the ignition will turn the lamp OFF and will exit the
limp-home procedure.
Exit limp-home procedure
"Exit limp-home procedure" means that, when a rising edge on the ignition occurs:
• The key can be read and is known : F_Try is reset, and engine start is allowed.
• The key can not be read or is unknown : the "IMMO" indicator starts blinking at 2Hz (duty cycle ON/OFF=1)
Inhibtion
If a wrong PIN has been entered 5 times in a row, the horn is activated at a 2.5Hz rate for 30 seconds and the system
isinhibited for 20 seconds. Inhibition means that engine start is not allowed (ie. the ICU is locked), and that the PIN can
not be entered. Each further incorrect try will increase the inhibit time by 20 seconds. The maximum inhibition time is
limited to 60 seconds. The inhibition is turned OFF:
• When the time-out is elapsed. In that case, the ICU remains locked, but the user may enter the PIN again.
• When the user turns the ignition ON with a correct key. In that case, the ICU is unlocked.
Correct PIN entered
If the entered PIN corresponds to the stored PIN, the ICU is unlocked and the passive arming delay is set to a calibration
value (i.e. 20senconds) specific to the limp-home procedure. The lamp blinks to indicate to the user to switch the ignition
OFF and ON again, so that the ICU and the ECM can communicate and "Unlock" the engine. While the PIN is being
entered, the ICU is locked. Therefore, the ECM may continuously send ECM's request to the ICU. When the user enters
the correct PIN, the ICU becomes unlocked and answers the ECM request with unlock status. "IMMO" indicator goes out.
If the ignition is switch off for more than the passive arming delay (i.e. 20 seconds), the ICU is locked again.
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