Power Locks: Description and Operation

Power Door Locks/Keyless Entry/Security System

How the Circuit Works

The power door locks, keyless entry, and security 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
- MICU
- Relay Control Module

Power Supply
Battery voltage is supplied at all times through fuse 6 (in the under-dash fuse/relay box) to the keyless receiver unit and through fuse 7 (in the under-dash fuse/relay box) to the MICU, the door multiplex control unit, and the security indicator.

Fuse 7 (in the under-hood fuse/relay box) is hot at all times and supplies battery voltage to the relay control module.

Fuse 8 (in the under-dash fuse/relay box) is hot at all times and supplies battery voltage to the MICU and the trunk lid opener switch.

Fuse 27 (in the under-dash fuse/relay box) is hot at all times and supplies battery voltage to the door multiplex control unit.

With the ignition switch in ON (II) or START (III), battery voltage is supplied through fuse 21 (in the under-dash fuse/relay box) to the MICU and to the keyless receiver unit.

System Description

Door Locks (Switch Operation)
The driver's door lock switch links directly to the door multiplex control unit located within the power window master switch. All lock and unlock commands from this switch are communicated across the multiplex integrated control system to the MICU.

The following lock or unlock control signals are also communicated to the MICU:
- Front Passenger's Door Lock Switch
- Door Lock Knob Switches
- Driver's Door Key Cylinder Switch

According to the switch request, the MICU directly operates the power supply and the grounding signals to the reversible door lock motors for lock and unlock modes.

Inserting the key into the driver's door 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 lock switch will lock all the doors.

Door Locks (Remote Transmitter Operation)
The doors can be locked or unlocked by the remote transmitter. The receiver antenna for the keyless system is located in the keyless receiver unit. The keyless receiver unit communicates lock and unlock commands directly to the door multiplex control unit. The door multiplex control unit communicates commands across the multiplex integrated control system to the MICU. According to the command, the MICU directly operates the power supply and the grounding signals to the reversible 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 keyless transmitter will lock all the doors, and set the security system.

Security
The security system is incorporated within the power door locks and keyless entry. When the vehicle is locked by the driver's door key cylinder switch, either door lock switch, or the remote transmitter, the security system is activated. The security system monitors the following signals:
- Audio Unit connection
- Door Lock Knob Switches
- Door Switches
- Ignition Key Switch
- Security Hood Switch
- Trunk Lid 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 energized. The exterior lights will flash, and the horns will sound for 2 minutes.