Remote Keyless Entry System Circuit Description - GMC Chevrolet Camaro 1998 Service Manual

Body.and Accessories
Locking the Doors
Press the LOCK button in order to perform the
following operations:
• Lock all of the doors
• Deactivate the illuminated entry
• Arm the universal theft-deterrent system
Panic Mode
Press the button that is marked with the horn symbol
in order to activate the emergency panic mode.
This mode will activate the horn and the parking lights
intermittently until the panic mode button is
pressed again.
Remote Control Door Lock Transmitter
The remote control door lock transmitter transmits a
radio signal to the body control module (BCM).
The BCM controls the functions of the transmitter.
The transmitter range is approximately 9 m (30 feet).
The transmitter data is encrypted, and changes
with each use. If the transmitter buttons are pressed
too many times out of range from the vehicle the
transmitter and the BCM will get out of
synchronization. This will result in the transmitter
appearing not to work at all. This situations will occur
after the transmitter button is depressed more that
256 time when it is out of range from the vehicle. This
may also be necessary if the transmitter battery
has been replaced and the buttons were pushed a few
times out of range. If the transmitter and the BCM
get out of synchronization, re-synchronize the
transmitter and the BCM. Refer to Re-synchronizing
Transmitter and Body Control Module.
Re-Synchronizing Transmitter and Body
Control Module (BCM)
Press both lock and unlock on the transmitter and
hold for approximately 8 seconds. This will attempt to
match security codes.
Body Control Module (BCM)
The Body Control Module (BCM) is battery fed. The
BCM is always monitoring the transmitter signal. When
the BCM receives the correct transmitter signal the
following actions occur:
1 . A transistor driver energizes the correct lock
control relay coil.
2. The transistor driver will arm the universal
theft-deterrent, if equipped.
3. The doors lock.
The BCM also regulates which lock control relays will
be energized in order to perform the following
operations:
• Unlock the doors
\1 •
Release the rear compartment lift window panel
• Disarm the universal theft-deterrent, if equipped
For replacement of the BCM, refer to Body Control
Module Replacement
Keyless Entry 8-557
Remote Keyless Entry System Circuit
Description
Circuit Operation
The body control module (BCM) is designed with an
internal antenna. The BCM picks up transmitted
radio frequencies from a hand held remote control
door lock transmitter. The transmitter has sufficient
power for operating the system from up to 7-10 meters
(22-33 ft) from the vehicle.
The side door lock actuators and the rear compartment
lid release actuator contain an electronic circuit
breaker (ECB). ECB resistance increases if the
actuator is overloaded. Resistance returns to normal
after the voltage is removed from the actuator
terminals.
Remote Control Door Lock Transmitter
Functions
Lock
When the lock button on the remote control door lock
transmitter is pressed, the body control module (BCM)
grounds the coil of relay 5. A voltage pulse is
applied from the BCM through circuit 295 to both side
door lock actuators. Ground is applied from G200
through circuit 650, the BCM and circuit 694
and circuit 1663 to the actuators. the driver and
passenger doors lock. The BCM turns off all of the
courtesy lamps as visual confirmation that a lock
function was performed.
Unlock
When the unlock button on the remote control door
lock transmitter is pressed once, the body control
module (BCM) grounds the coil of relay 3. A voltage
pulse is applied from the BCM through circuit 694
to the left side door lock actuator. Ground is applied
from G200 through circuit 650, the BCM and
circuit 295 to the actuator. The driver door unlocks.
The BCM also grounds the dome/courtesy lamps
through CKT 156 for approximately 40 seconds
to provide illuminated entry. The BCM then initiates
the theater dimming function until the BCM receives
an ignition ON input.
When the unlock button on the transmitter is pressed
a second time within 5 seconds, the BCM grounds
the coil of relay 3. A voltage pulse is applied from the
BCM through circuit 1663 to the right side door
lock actuator. Ground is applied from G200 through
circuit 650, the BCM and circuit 295 to the actuator.
The passenger door unlocks.