Circuit Description
Power Door Locks/Keyless Entry/Security AlarmHow the Circuit Works
The power door locks, keyless entry, and the security alarm system are part of the multiplex integrated control system. The use of multiplexing incorporates all three systems together. The following multiplex control units operate the systems:
- Door multiplex control unit
- Gauge control module
- Multiplex integrated control unit (MICU)
- Relay control module
Power Supply
With the ignition switch in the ON (II) or START (III) position, battery voltage is applied through fuse 21 to the multiplex integrated control unit and to the door multiplex control unit. Fuse 21 and the MICU are located in the under-dash fuse/relay box. Fuse 7 (in the under-hood fuse/relay box), is hot at all times. It supplies battery voltage to the to relay control module.
Fuse 7 (in the under-dash fuse/relay box) is hot at all times and supplies battery voltage to the MICU, the door multiplex control unit, and the gauge control module.
Fuse 8 (in the under-dash fuse/relay box) is hot at all times and supplies battery voltage to the MICU
System Description
Door Locks (switch operation)
The driver's door lock switch is part of the door multiplex control unit. The door multiplex control unit is located within the power window master switch. All lock and unlock commands from this switch are communicated across the multiplex communication line to the MICU located in the under-dash fuse/relay box. The following lock or unlock control signals are also communicated to the MICU:
- Passenger's door lock switch
- Door lock knob switches
- Driver's key cylinder switch According to the switch request, the MICU directly operates the power supply and the grounding signals to the reversible electric door lock motors for lock and unlock modes.
Inserting the key into the driver's key cylinder switch and turning the key one time will unlock the driver's door. Turning the key a second time will unlock all the doors. This is a multiplex controlled response.
Locking the doors from the driver's door switch will lock all the doors.
Door Locks (Keyless Transmitter Operation)
The doors can be locked or unlocked from the hand-held keyless transmitter. The receiver antenna for the keyless system is located in the power window master switch (door multiplex control unit).
All lock and unlock commands from the keyless transmitter are communicated across the multiplex communication line to the MICU.
According to the request, the MICU directly operates the power supply and the grounding signals to the reversible electric door lock motors for lock and unlock modes.
Pressing the unlock button one time will unlock the driver's door. Pressing the unlock button a second time will unlock all the doors. This is a multiplex controlled response.
Pressing the lock button of the remote transmitter will lock all the doors, and set the security system.
Security
The security system is incorporated with the power door locks. When the vehicle is locked with the door key, lock knob, door lock switch, or the remote transmitter, the security system is activated. The system will set completely 15 seconds after the hood, doors, and trunk are closed. The security system monitors the following signals:
- Battery voltage
- Door lock knob switches
- Door switches
- Ignition key switch
- Radio connection
- Security hood switch
- Trunk key cylinder switch (sedan)
- Trunk latch switch
When any of the monitored systems is disturbed, the alarm is triggered. Along with the inability to start the vehicle, the taillight relay and the horn relay are activated. All exterior parking lights will flash and the horns will sound.
Information about arming and disarming the security system is multiplex communicated to the gauge control module for operation of the security indicator lamp.