Grand Caravan FWD V6-3.8L VIN L (2001)
Body Control Module: Description and Operation
Part 5 of 5
REAR WINDOW DEFOG/HEATED MIRROR/FRONT WIPER DE-ICE
The defroster button located on the HVAC control controls the rear window defogger, heated side view mirrors and front wiper de-icer grid. In
addition the front wiper de-ice function is turned ON when front defog/defrost mode is selected.
When the defroster button is pushed, the HVAC control sends a bus message over the PCI bus to the Front Control Module (FCM) which controls
the Rear Window Defogger relay. The defroster LED will illuminate when the defroster function is ON. The defroster will function for 10 minutes
or can be cycled OFF sooner by pressing the defroster button again. The front wiper de-icer grid receives its 12 volts from the accessory relay
through fuse 11 and the HVAC control module supplies the grid ground.
VEHICLE THEFT SECURITY SYSTEM
The Vehicle Theft Security System (VTSS) is part of the Body Control Module (BCM). The BCM monitors the vehicle doors, liftgate, hood, and
the ignition for unauthorized operation. The alarm activates by sounding the horn, flashing the headlamps and the VTSS indicator lamp. The
VTSS does not prevent engine operation, this is done with the Sentry Key Immobilizer Module (SKIM). Passive arming occurs in one of two
ways. Upon normal vehicle exit by removing the ignition key, opening the driver door, locking the doors with the power lock, and closing the
driver door, or by removing the ignition key, opening the driver door, closing the driver door, and locking the doors with the Remote Keyless
Entry (RKE) transmitter. The VTSS indicator lamp will flash for approximately 15 seconds during the arming process. If there is no interruption
during the arming process, upon completion the VTSS indicator lamp will flash at a slower rate. When the BCM receives an input to trigger the
alarm, the BCM will control the outputs of the headlamps, horn, and VTSS lamp for approximately 18 minutes.
Arming (Active and Passive)
Active arming occurs when the RKE transmitter is used to lock the vehicle doors, whether the doors are open or closed. The arming process is
complete only after all doors are closed.
Passive arming occurs when the ignition key is removed, the driver door is opened, and the doors are locked with the power door lock switch,
and the door is closed.
Disarming (Active and Passive)
Active disarming occurs when the RKE transmitter is used to unlock the vehicle doors. This disarming will also halt the alarm once it has been
activated.
Passive disarming occurs upon normal vehicle entry (unlocking driver door with the key). This disarming will also halt the alarm once it has
been activated.
Tamper Alert
The VTSS tamper alert will sound the horn three times upon disarming to indicate a tamper condition has occurred.
Manual Override
The system will not arm if the doors are locked using the manual lock control or if the locks are actuated by an inside occupant after the doors
are closed.
Diagnosis
For complaints about the Vehicle Theft Alarm triggering on its own, use the DRBIII(R) and read the Last VTSS Cause status.
NOTE: A POWERTRAIN CONTROL MODULE FROM A VEHICLE EQUIPPED WITH A VEHICLE THEFT SECURITY SYSTEM
CANNOT BE USED IN A VEHICLE THAT IS NOT EQUIPPED WITH A VEHICLE THEFT SECURITY SYSTEM. IF THE VTSS
INDICATOR LAMP COMES ON AFTER IGNITION ON AND STAYS ON, THE PCI BUS COMMUNICATION WITH THE
POWERTRAIN CONTROL MODULE HAS POSSIBLY BEEN LOST.
WIPER SYSTEM
Frontwiper
The front wiper/washer system consists of the following features: lo-hi-speed, mist wipers, intermittent wipers and wipe after wash. The front
wiper system is only active when the ignition switch is in the RUN/ACC position. The vehicle operator selects the front wiper function using the
front wiper switch (a resistive multiplexed stalk switch) which is integral to the Multi-Function Switch. The front wiper switch is hardwired to the
Body Control Module (BCM). Upon receiving a wiper switch signal, the BCM sends a PCI Bus message to the Front Control Module (FCM). The
FCM controls the ON/OFF relay, the HIGH/LOW relay and the front and rear washer pump motors.
The Wiper system utilizes the BCM to control the ON/OFF and hi/low relays for the low and hi speed wiper functions, intermittent wiper delay as
the switch position changes, pulse wipe, wipe after wash mode and wiper motor functions. The BCM uses the vehicle speed input to double the
usual delay time below 10 MPH (6 KPH).
Speed Sensitive Intermittent Wipe Mode
There are 5 individual delay time settings with a minimum delay of 1.7 seconds to a maximum of 18.4 seconds. When the vehicle speed is under
10 MPH (6 KPM), the delay time is doubled, providing a delay range of 3.4 seconds to 36.8 seconds.
