Body Control Module: Description and Operation
Part 3 of 3
LOW TIRE PRESSURE WARNING MODULE MODES
When the ignition is turned to the "run" position, the LTPW module performs a complete self-check of all electrical components in the system.
After the vehicle reaches a speed of approximately 33 km/h (20 mph), the module will perform a dynamic check of the tire pressure
transmitters. During the dynamic check, the vehicle speed may fall below 33 km/h (20 mph) but not for longer than one minute. The LTPW
module will confirm if the Radio Frequency (RF) transmissions from each tire pressure transmitters have been received.
If any component exhibits a trouble condition during the initialization or dynamic check, the LTPW module will set a DTC and illuminate the
"Low Tire" warning lamp. A fault can also occur if the LTPW module (after initialization) does not receive any transmissions from the
transmitter/sensor for six consecutive ignition cycles.
Diagnostic mode is considered to be any time that the DRB is hooked up to the DLC and is communicating with the LTPW module. In
diagnostic mode, the LTPW module does not monitor or accept the tire pressure sensor/transmitter signal. This means that you cannot read the
tire pressure sensor/transmitter transmission information while driving the vehicle with the DRB hooked up.
The Program Mode enables the LTPW module to detect which wheel (LF, RF, RR, LR) is sending the signal. The module must learn each of
the four tire pressure sensor/transmitters' identifications (ID). This transmitter ID "learning" is used so that if any other signals are being
received by the LTPW module at this frequency, it won't be misinterpreted.
Programming is initially done at the assembly plant. If a LTPW module fails or one or more tire pressure sensor/ transmitter(s) fails, after
replacement of the faulty component the LTPW module's diagnostic memory must be reprogrammed or cleared in order to relearn the
The DRB can place the module in Program Mode. It is possible to reprogram only one tire pressure sensor/transmitter. To program a module
place a magnet (special tool 8192) on the end of the LF wheel valve stem for approximately six seconds. The magnet will energize and close
the Reed switch. With the Reed switch closed, the transmitter will transmit the identification (ID) and tire pressure to the module. After the
module has learned that particular tire pressure sensor/ transmitter ID, the magnet should be moved to each of the other wheels in a clockwise
direction. Hold the magnet at each wheel for six seconds before moving onto the next wheel. Exit the Program Mode. The module will store
the locations of each transmitter ID. Using the DRB, verify that the module programming is complete by looking at the tire pressure
sensor/transmitter ID's and pressure values.
MANUAL A/C (HVAC)/REAR WINDOW DEFOGGER
The Prowler comes standard with manual air-conditioning. The actuators for blend-air and fresh/recirc are cable operated. The mode door is
electrically activated by the BCM based on input from the HVAC control head. The BCM uses an evaporator fin probe to prevent evaporator
When the ignition is in the "run" position, the body control (BCM) monitors the evaporator temperature state and the status of the A/C switch.
Based on this information, the BCM sends a CCD message to the powertrain control module (PCM) indicating the A/C switch status and the
evaporator temperature state.
The body control module controls the mode door position by receiving different voltage levels from the HVAC control over the HVAC mode
sense circuit. Included in this signal is the input for the rear window defogger. The Rear Window Defogger button is located in the center of the
Mode Control knob. Press this button once to turn on the Rear Window Defogger and a second time to turn it off. A LED in the button shows that
the defogger is on. The defogger turns off automatically after 10 minutes of operation. Each later activation will allow 5 minutes of operation.
The timer functions for the rear window defogger are controlled by the BCM.
POWER DOOR LOCKS
Power door locks are standard equipment on all Prowler vehicles and have the following features:
Automatic door locks - automatically lock the doors when all doors are closed and the vehicle reaches a speed 18 mph. This feature can be
enabled/disabled by the DRB Ill or by the customer cycling the ignition key from "Off to Run" four times (leaving the key in the off position)
then pressing any power "lock" switch and removing the key from the ignition switch. A single chime will signal programming completed.
Power door lock inhibit feature - cancels lock switch actuation when the key is in the ignition and either door is open.
To prevent motor burnout, the BCM will pulse the lock/unlock relays a maximum of 4 seconds. Even though the switch may be held down
This vehicle is NOT equipped with central locking (unlocking one door with the key opens both doors). However, the vehicle is equipped with
door key cylinder switches that are used exclusively for the vehicle theft security system and will arm or disarm the system.
Remote Keyless Entry (RKE) (Standard Equipment)
The body control module interfaces with the remote keyless entry receiver module via a one-way serial bus interface. The RKE module is
located under the left side of the instrument panel top cover. It does not actuate relays directly but receives the signal from the transmitter and
then communicates with the BCM.