Page 335 - 05. Subyek Teknik Mesin - Automobile Mechanical and Electrical Systems Automotive Technology Vehicle Maintenance and Repair (Vehicle Maintenance Repr Nv2) by Tom Denton
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Electrical systems 317
RF Receiver/
Transmitter
Supply
Control Unit
Door Switch(s) M M M M
Lock Motors
Other Systems
(Alarm etc.)
Figure 3.121 Circuit to operate door locks
code and sends it in an electrical form to the main control unit. If the received
code is correct, the relays are triggered and the door locks are either locked or
unlocked. If an incorrect code is received on three consecutive occasions when Key fact
attempting to unlock the doors, then some systems will switch off until the door Trillions of different code
is opened by the key. This technique prevents a scanning-type transmitter unit combinations are used in modern
from being used to open the doors. locking systems.
3.4.5.5 Windows
The basic form of electric window operation is similar to many of the systems
discussed so far in this module; that is, a motor reversing system either using
relays or directly by a switch. More sophisticated systems are now popular for
reasons of safety as well as improved comfort. The following features are now
available from many manufacturers:
one touch up or down
●
inch up or down
●
lazy lock
●
back off or bounce back.
●
The complete system consists of an electronic control unit containing the
window motor relays, switch packs and a link to the door lock and sunroof
circuits. This is represented in the form of a block diagram in Fig. 3.122 .
When a window is operated in ‘one-touch’ mode, the window is driven in the
chosen direction until the switch position is reversed, the motor stalls or the
ECU receives a signal from the door lock circuit. The problem with one-touch
operation is that if a child, for example, should become trapped in the window Key fact
there is a serious risk of injury. To prevent this, a bounce-back feature is used. A bounce-back feature is used to
An extra commutator is fi tted to the motor armature. This produces a signal, via prevent people and things being
two brushes, proportional to the motor speed. Hall sensors are used on some trapped in windows.
systems. If the rate of change of speed of the motor is detected as being below a
certain threshold, the ECU reverses the motor until the window is fully open.