Part 2A

AUTOMATIC ZONE CONTROL (AZC)
The AZC (Automatic Zone Control) system will be the auto industry's first sport utility vehicle to offer automatic dual-zone temperature control with infrared sensing technology for superior occupant comfort. With AZC, occupants select a comfort temperature, not the actual passenger compartment air temperature. The temperature in the passenger compartment at any time may be slightly higher or lower than the selected value. For instance, on sunny summer days the air flow will probably be cooler than the comfort temperature; on cold or cloudy days and at night it will probably be slightly warmer.

A simplified control system for operation of mode, recirculation, and temperature control doors provides positive positioning without the complexity of feedback from position sensors. Knowing the number of operating motor revolutions required to provide full travel, and the number of motor commutator pulses per revolution, the control system runs the motor for the number of commutator pulses corresponding to the desired door position. To maintain accuracy, the system recalibrates itself periodically at known zero or full travel conditions.

The AZC blower control provides continuously variable control of air flow rate to meet occupant comfort requirements. Pulse-width modulation of blower power allows the blower to operate at any speed from stationary to full speed.

The AZC module uses infrared sensing technology to control occupant comfort levels, not the actual passenger compartment air temperature. Dual infrared sensors mounted in the face of the control unit independently measure the surface temperature to maintain customer-perceived comfort temperature under changing conditions. Dual Zone temperature control provides wide side-to-side variation in comfort temperature to exceed the needs of either front seat occupant. This sensing system replaces interior air temperature and solar sensors used to approximate direct sensing control through complex control programs.

The infrared temperature sensor cannot be adjusted or repaired and, if faulty or damaged, the module must be replaced.

NOTE: THE INFRARED SENSOR WINDOW MAY BE PERMANENTLY DAMAGED IF ANY TYPE OF COSMETIC VINYL DRESSINGS ARE ALLOWED TO CONTACT THE LENS. AVOID SPRAYING OR WIPING THIS AREA WITH ANY CLEANER OR CONDITIONER. THIS MAY RESULT IN IMPAIRED TEMPERATURE SENSING AND CONTROL.

Functional Operation
The AZC system communicates over the PCI bus (Programmable Communication Interface multiplex system) and allows diagnostics with the DRBIII (R).

Through the PCI bus, the AZC head receives engine temperature and engine RPM, to allow for cold engine blower lock-out and wide open throttle A/C cut-out. It also receives vehicle speed (for determination of the amount of air flowing through the condenser), a pulse width dimming signal for the VF display. U.S./Metric status, and the ambient air temperature. The ambient air temperature in previous years was hard wired to the ATC head. Now Bus communication allows the Body Control Module to send the ambient temperature information to the AZC head and the overhead console.

The AZC head is responsible for maintaining the interior temperature of the vehicle based on the customer's input on the faceplate and the I/R sensor input. The faceplate contains two large rotary knobs that control fan speed and mode selection. It also contains two smaller rotary knobs for the temperature control of each zone. One of the three buttons place the system in recirculation mode, the button across from that, turns the A/C ON or OFF. The third button on the bottom, turns the Rear Defogger ON and OFF. All three of these buttons contain a LED indicator showing an ON or OFF state.

The figure in the VF display on the control head is represented as a "stickman", and the arrow indicates the direction of the airflow inside the vehicle. The A/C button allows the compressor to be switched ON or OFF, except in defrost and automode. The Recirc button allows air to be drawn from the inside of the vehicle only, except in defrost. On high temperature/humidity days, recirc mode should provide better cooling than normal mode because the inside air is recirculated within the vehicle.

This system also allows increased flexibility because it can be operated in a manual mode. In manual mode the customer may select the airflow, fan speed, and whether the compressor will operate. The system can also be put into manual fan control by moving the fan control knob from automatic to one of the manual blower speed selections. Manual mode offers 10 different blower speeds, the automatic mode has an infinite number available.

The AZC system in 2000 is fully addressable with the DRBIII (R) and it still retains the on-board diagnostics from the past years. For more thorough explanation of the on-board diagnostics, please refer to the Service Information. All of the inputs to the AZC head can be read with the DRBIII (R) and some outputs can be actuated. Diagnosis of the AZC system should begin with the reading active codes on the DRBIII (R). If no active codes are displayed, read the stored codes next.

If any of the motor actuators are replaced or the A/C, heater housing is replaced, the system should be recalibrated. This happens automatically at battery disconnect or it can be accomplished using the DRBIII (R). Without recalibration, the AZC head will not be sure of the actuators position and may result in poor air control.

Active Codes
An active trouble code indicates an on-going malfunction. The defect is present every time the AZC head checks the circuit or function. It is not possible to erase an active code. Active codes will change to stored once the reason for the code has been corrected.

Stored Codes
A stored code indicates that there was an active code present at some time. The reason for the active code was corrected and the code was changed to the stored code.

If the reason for the code was corrected, the AZC head will erase the code after 72 keys cycles. The code may also be erased from the head using the DRBIII (R).

If no obvious problems are found, read active codes on the DRBIII (R) while wiggling the harness and connectors. Recheck for codes periodically as you work through the system. This procedure may uncover a malfunction that is difficult to locate.

BODY CONTROL MODULE
The Body Control Module (BCM) supplies vehicle occupants with visual and audible information and controls various vehicle functions. To provide and receive information, the module is interfaced to the vehicle's serial bus communication network (Programmable Communication Interface or PCI bus). This network consists of the Powertrain Control Module (PCM), the Memory/heated Seat Module (MHSM, MSM or HSM), the Sentry Key Immobilizer Module (SKIM), the Transmission Control Module (TCM), the Electro/mechanical Instrument Cluster (MIC), the Driver Door Module (DDM), the Passenger Door Module (PDM), the Airbag Control Module (ACM), the Antilock Brake Module (ABS), the optional Electronic Vehicle Information Center (EVIC), the optional PCI radio and the optional Automatic Zone Control Module (AZC). The BCM is operational when battery power is supplied to the module, ignition switch power is needed for ignition switched functions.

The BCM provides the following new features:
- Full control of all exterior and interior lamps, including these features:
- A Battery Saver automatically turns OFF all exterior and interior lamps within 8 minutes after the ignition is turned OFF if they are not turned OFF by the driver. This includes the front and rear reading/courtesy lamps and the cargo area dome lamp, even if they are turned ON manually.
- Theater-style interior lighting dims gradually when the doors are closed.
- Interior courtesy lamp operation may be "defeated" using the dimmer control ring on the left stalk switch.
- Instrument panel light intensity may be maximized for daytime visibility with the head lamps or parking lights by using the dimmer control ring on the left stalk switch.

- A refined Accessary/Sunroof Delay allows operation of the sunroof as well as the power windows. In addition, the time has been extended from 30 to 45 seconds after the ignition is switched OFF for added convenience. As in the past, the delay terminates (window and/or sunroof ceases) if a door is opened, which helps protect occupants from possible injury.
- Beep tones for warnings and programming actions associated with the Sentry Key Immobilizer system and the EVIC.

The BCM also provides the following features:
- Intermittent wipe and low speed wiper control
- Wiper system status
- Ignition ON/OFF timer
- VF displays synchronization
- Rear door and liftgate ajar status
- Acquisition & transmission of external temperature
- A/C select switch status
- Chime
- Courtesy lamps with fade to OFF feature
- Reading lights/glove box lamp load shedding control
- Exterior lighting control including automatic headlamps, fog lamp control and parking lamps
- Exterior lamp status
- Headlamp time delay upon ignition OFF and head- lamps switch OFF
- Parade mode
- Illuminated entry
- Instrument panel dimming
- Vehicle theft security system with panic & horn and hazard lamp activation
- Key-in ignition switch interface
- Brake fluid level switch/park brake switch interface
- Seatbelt reminder
- Speed sensitive intermittent wipe control
- Remote radio switch interface to radio
- Vehicle ignition status
- BCM self diagnostics
- Liftgate courtesy lamp disable
- Rear window defogger control
- Accessory delay control (windows and sunroof)
- Fuel economy and Distance To Empty (DTE) calculations
- Heated seat switch status
- Exterior lamp load shed
- Support of EVIC programmable features

The BCM receives information over the PCI bus from the PCM in order to support certain features. The required information is as follows:
- Engine RPM
- Engine and battery temperature
- Injector on time and distance pulses
- Vehicle speed
- Engine Model
- Fuel tank level
- Vehicle identification number

The BCM provides the PCM with information on the A/C switch status.

The 2000 WJ has several programmable features which can be enabled/disabled by using the EVIC or the DRBIII (R).

CHIME SYSTEM
The chime system in the WJ utilizes four modules. The Body Control Module (BCM), the Electronic Vehicle Information Center (EVIC), and Mechanical Instrument Cluster (MIC), and the SKIM module. The 2000 WJ also has the PCM included and has the ability to request a chime. The chime is located in the BCM module. Each module monitors circuits and systems, then sends a request for a chime to the BCM. The BCM is constantly monitoring the PCI bus for a chime request message. If a MIC, EVIC, or SKIM monitored system requires a chime to sound, the request for the chime will come from the MIC, EVIC, or SKIM but the BCM will actually sound the chime.

The chime will sound for the following conditions:

MIC Requested Chime Messages
- Airbag
- Check Gauges:
- Charging Voltage Low
- Coolant Temp High
- Low Oil Pressure
- Charging Voltage High
- Low Fuel
- ABS
- Low Battery Voltage

BCM Initiated Chime Messages
- Headlamp ON with ignition OFF and driver door open
- Key in ignition with ignition OFF and driver door open
- Seat Belt Warning

EVIC Chime Requested Messages
When the following messages are displayed the EVIC will send a chime request to the BCM. The BCM will respond with a series of chimes.
- Turn signal ON for more than 1.0 mile
- Service reminder
- Coolant level low
- Washer fluid low

Critical Speed Chart:

- Door or liftgate ajar (when critical speed is reached)

Sentry Key Immobilizer System
The Sentry Key Immobilizer System (SKIS) also uses tactile beep support from the chime warning system. The Sentry Key Immobilizer Module (SKIM) is programmed to send chime request messages over the Programmable Communications Interface (PCI) data bus to the Body Control Module (BCM) to provide audible confirmation that:
- the SKIM has been successfully placed in the Customer Learn mode.
- A new Sentry key transponder has been successfully programmed by the SKIM.

See the the vehicle glove box for more information on the features, use and operation of the SKIS. Refer to Sentry Key Immobilizer System in the Description and Operation of the service information - Vehicle Theft/ Alarm systems for more information on the SKIS. For diagnostic information, refer to the Powertrain Diagnostic Information.
Testing and Inspection

THE DOOR AJAR SYSTEM
Inputs are used by several of the control modules on this vehicle. The rear doors and liftgate switches are hard wired to the body control module while the driver and passenger switches are wired to their respected door modules. The DRBIII (R) input/outputs will display the state of the switch not the respective door state. In other words, if the door is closed the DRB should show "Open" and when the door is open the DRB should show "closed". If the ajar state is "Closed" when the door is closed, this would indicate a shorted circuit. If the ajar state is "Open" when the door is open, this would indicate an "Open" circuit.

DOOR MODULES
A multiplexed door module is located on each front door, driver door (DDM) and passenger door (PDM). They control the following features: power door locks, automatic (rolling) door locks, driver window express down, memory recall functions (memory seats and mirrors), remote keyless entry, power mirrors, heated mirrors, door key cylinder disarm (driver door only), door lock inhibit and auto unlock on exit, Reduced wiring complexity is a key feature of using multiplexed door modules. These modules are addressable with the DRBIII (R) from the "Body" menu to facilitate faster and easier diagnosis.

Power Windows
The power windows can be raised or lowered from the driver's door module (DDM) or the individual door switch. The DDM has a lock out switch that prevents the windows from being operated from any switch except the driver's door. When the switch is pressed, it also shuts OFF the individual door switch LED's.

A feature of this system allows the windows to be operated from any window switch for 45 seconds after the ignition is turned OFF, provided a front door is not opened. Another feature is the "Express Down" driver door only. When the driver presses the down switch to the second detent, the window will travel all the way down even if the switch is released. To stop the window travel, simply press the switch momentarily in either direction.

Twelve volts are provided on the rear window motor circuit on both the up and down circuits. The appropriate door module supplies this voltage. When the rear switch is pressed, the supply circuit to one side of the switch is opened and ground is provided making a complete circuit and therefore operating the window motor.

Power Door Locks
The power door locks are operated four different ways:
1. Front door lock switches
2. Auto (rolling) door lock feature (vehicle speed above 15 MPH (24 KPH) and all doors closed).
3. Auto unlock on exit (vehicle stopped after auto door locks had locked the doors, transmission in neutral or park and the drivers door is opened - all doors will unlock).
4. Remote Keyless Entry (RKE)

Door Lock Inhibit
When the key is in the ignition and in the OFF position, and either front door is opened, the lock switch on that door is disabled. The unlock switch is still functional. This protects against locking the vehicle with the keys still in the ignition. For example, if the driver's door is opened and the passenger front door closed, the locks are operational from the passenger door switch.

Remote Keyless Entry
When the lock button on the transmitter is pressed, all locks will lock, illuminated entry will be turned OFF, (providing all doors are closed) and the vehicle theft security system (if equipped) will be armed. When the unlock button on the transmitter is pressed one time, the driver front door will unlock, the illuminated entry will turn ON the courtesy lamps, the vehicle theft security system (if equipped) will be disarmed. When the button is pressed a second time, the other doors will unlock. This feature is programmable to open all doors on one press using the EVIC or the DRBIII (R).

The passenger door module (PDM) contains the RKE receiver. When the PDM receives a valid signal from the RKE transmitter, it will send a signal on the PCI bus to lock or unlock the doors. The RKE transmitter used radio frequency signals to communicate with the RKE receiver. If vehicle is equipped with the memory system, the memory message will be received as to which transmitter sent the signal (1 or 2).

Panic Function
When the panic button on the RKE transmitter is pressed it pulsates the headlamp, hazard lamps and horn relays and actuates the courtesy lamp relay. By pressing the button again the horn and exterior lamps will stop but the courtesy lamps will remain ON until the BCM times them out or the ignition is turned ON. The panic feature is able to be set if the ignition is ON but only if the panic button is pressed prior to the vehicle being started, it will continue for three minutes or until the vehicle has reached a speed of 15 MPH, if not canceled by the operator.

Actuating the headlamp, horn, hazard lamps and courtesy lamp relays with the DRBIII (R) will verify that the circuits and the body control module are OK. If the panic feature is still inoperable with both transmitters, replacement of the passenger door module will be necessary. If the function is inoperable with just one transmitter, then it is obvious that the transmitter must be replaced.

Rolling Code
The rolling code feature changes part of the transmitter message each time that it is used. The transmitter message and the receiver message increment together. Under certain conditions with a rolling code system (pressing a button on the RKE transmitter over 255 times outside the receiver range, battery replacement, etc.), the receiver and transmitter can fall out of synchronization. Note: That the lock function works from the RKE keyfob even in out of synchronization condition and therefore it could be verified by pressing the LOCK button on the RKE keyfob. To re-synchronize, depress and release the UNLOCK button on the RKE keyfob repeatedly (it may take up to eight cycles) while listening carefully for the power door locks in the vehicle to cycle, indicating that resynchronization has occurred.

Programmable Door Lock Features
- The RKE can be changed to unlock all doors with one press
- The Automatic Door Locks can be enabled/ disabled
- Auto Unlock on Exit can be enabled/disabled
- RKE horn chirp on lock can be enabled/disabled
- RKE optical chirp (turn signal lamps) can be enabled/disabled
- Program a new RKE transmitter (DRBIII (R) only)
- RKE linked to memory (if equipped with memory system) enabled/disabled (DRBIII (R) only). Allows memory to be operable only from the driver door switch.