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.

Pulse Wipe
When the wiper is in the OFF position and the driver presses the Wash button for more than 0.062 Seconds, but less than 0.5 seconds, 2 wipe cycles in low speed mode will be provided.

Park After Ignition OFF
Because the wiper relays are powered from the battery, the BCM can run the wipers to park after the ignition is turned OFF.

Wipe After Wash
When the driver presses the wash button for over 0.5 seconds and releases it, the wiper will continue to run for 2 additional wipe cycles.

Rear Wiper
The rear wiper/washer system consists of the following features: mist wipers, intermittent wipers and wipe after wash. The rear wiper system is only active when the ignition switch is in the RUN/ACC position. The vehicle operator selects the rear wiper function using one of the three buttons on the dash mounted rear wiper switch. The rear wiper switch is hardwired to the Body Control Module (BCM). Upon receiving a wiper switch signal, the BCM provides 12 volts to the rear wiper motor. Rear washer occurs when the BCM receives a rear washer switch ON input. The BCM sends a PCI Bus message to the FCM requesting rear washer ON. The FCM activates the rear washer by providing a ground for the rear washer motor.

Speed Sensitive Intermittent Wipe Mode
The delay setting of the Rear Wiper system is based solely on the vehicle speed. The delay time is defined as the amount of time from the start of a wipe to the beginning of the next wipe. The Rear Wiper system delay time is based on the following:
7.75 - (MPH x .05) = Seconds delay

Examples:
At zero (0) MPH the delay is 7.75 seconds.
At 100 MPH the delay is 2.75 seconds.

Wipe After Wash
When the driver presses the wash button for over 1.5 seconds and releases it, the wiper will continue to run for 2 additional wipe cycles.

USING THE DRB
Refer to the DRB user guide for instructions and assistance with reading trouble codes, erasing trouble codes, and other DRB functions.

DRBIII(R) ERROR MESSAGES
Under normal operation, the DRB will display one of only two error messages: user-requested WARM Boot or User-Requested COLD Boot. If the DRB should display any other error message, record the entire display and call the STAR Center. This is a sample of such an error message display:
ver:2.14
date: 26 Jul93
file: key_iff.cc
date: Jul26 1993
line: 548
err: Ox1
User-Requested COLD Boot

Press MORE to switch between this display and the application screen.

Press F4 when done noting information.

DRBIII(R) DOES NOT POWER UP (BLANK SCREEN)
If the LED's do not light or no sound is emitted at start up, check for loose cable connections or a bad cable. Check the vehicle battery voltage (data link connector cavity 16). A minimum of 11 volts is required to adequately power the DRB. Check for proper grounds at DLC cavities 4 and 5.

If all connections are proper between the DRB and the vehicle or other devices, and the vehicle battery is fully charged, an inoperative DRB may be the result of a faulty cable or vehicle wiring.

DRB Scan Tool:

Display Is Not Visible
Low temperatures will affect the visibility of the display. Adjust the contrast to compensate for this condition.

WARNINGS
Vehicle Damage Warnings
Before disconnecting any control module, make sure the ignition is "OFF". Failure to do so could damage the module.

When testing voltage or continuity at any control module, use the terminal side (not the wire end) of the connector. Do not probe a wire through the insulation; this will damage it and eventually cause it to fail because of corrosion. Be careful when performing electrical tests so as to prevent accidental shorting of terminals. Such mistakes can damage fuses or components. Also, a second code could be set, making diagnosis of the original problem more difficult.

Road Testing A Complaint Vehicle
Some complaints will require a test drive as part of the repair verification procedure. The purpose of the test drive is to try to duplicate the diagnostic code or symptom condition.

WARNING: BEFORE ROAD TESTING A VEHICLE, BE SURE THAT ALL COMPONENTS ARE REASSEMBLED. DURING THE TEST DRIVE, DO NOT TRY TO READ THE DRBIII(R) SCREEN WHILE IN MOTION. DO NOT HANG THE DRBIII(R) FROM THE REAR VIEW MIRROR OR OPERATE IT YOURSELF. HAVE AN ASSISTANT AVAILABLE TO OPERATE THE DRBIII(R).

REQUIRED TOOLS AND EQUIPMENT
DRBIII(R) (diagnostic read-out box)
Jumper wires
Ohmmeter
Voltmeter
Sentry Key Tester
Test Light
8310 Airbag System Load Tool
8443 SRS Airbag System Load Tool
Diagnostic Junction Port Tester 8339

GLOSSARY OF TERMS
ABS Antilock brake system ACM airbag control module
AECM Airbag electronic control module (ACM)
ASDM Airbag system diagnostic module (ACM)
ATC Automatic temperature control
BCM Body control module
CAB Controller antilock brake
CMTC Compass/mini-trip computer
CPA Connector positive assurance
DAB Driver airbag
DLC Data link connector
DTC Diagnostic trouble code
DR Driver
EBL Electric back lite (rear window defogger)
EVIC Electronic vehicle information center
FCM Front control module
HVAC Heater ventilation, air conditioning
IPM Intelligent power module
LDU Lower drive unit
MIC Mechanical instrument cluster
MTC Manual temperature control
MSMM Memory seat/mirror module
OBD On board diagnostics
ODO Odometer
ORC Occupant restraint controller
PAB Passenger airbag
PASS Passenger
PCI Programmable Communication Interface (vehicle communication bus)
PCM Powertrain control module
PDC Power distribution center
PLG Power liftgate
PLGM Power liftgate module
PSD Power sliding door
PSDM Power sliding door module
PWM Pulse width modulated
RKE Remote keyless entry
SAB Seat airbag
SBT Seat belt tensioner
SIACM Side impact airbag control module
SKIM Sentry key immobilizer module
SKIS Sentry key immobilizer system
SQUIB Also called initiator (located inside airbag)
SRS Supplemental restraint system
TCM Transmission control module
VFD Vacuum fluorescent display
VTSS Vehicle theft security system