ELECTRICAL
25
DESCRIPTION AND OPERATION
Engine Running Detection
The BeCM has two methods of detecting that the
engine is running; tachometer pulse monitoring and
alternator charge input.
The tachometer pulse monitoring is used for safety
related functions i.e. memory seat one-touch
inhibition. The engine rpm thresholds for the
tachometer pulse monitoring is as follows:
Petrol 180 rpm
±
10%
Diesel 240 rpm
±
10%.
The alternator charge input is used for load control of
electrical functions. If certain functions are operating
simultaneously, i.e. both rear windows operating and
seat heaters active, the BeCM will determine which
function has priority and temporarily deactivate one
function.
Key Inhibit Solenoid (NAS/JAPAN Only)
NAS and Japanese automatic transmission vehicles
have a key inhibit function which prevents removal of
the ignition key if the automatic transmission selector
lever is not in the PARK position.
The key inhibit function is controlled by the BeCM.
The BeCM de-energises a key inhibit solenoid located
in the ignition switch assembly when a park signal is
passed to the BeCM from the PARK switch located in
the H-gate.
On vehicles up to 97.5MY, the key inhibit solenoid is
not de-energised until the BeCM receives a PARK
signal from the park switch and the ignition is moved
to position 0 (off).
On vehicles from 97.5MY, the key inhibit solenoid is
de-energised via the park switch, irrespective of the
ignition switch position. This overcomes key removal
problems if a rapid key removal is attempted.