Principles of Operation

PRINCIPLES OF OPERATION

The message center electronic functions use both hardwired inputs and the controller area network (CAN) to transmit and receive information. It is very important to understand:
- where the input (command) originates.
- all the information (messages) necessary in order for a feature to operate.
- which module(s) receive(s) the input or command message.
- if the module which received the input (message) controls the output of the feature, or if it outputs a message over the CAN circuit to another module.
- which module controls the output of the feature.

The message center provides the following features:
- Information displays
- Setup displays
- System check messages
- Warning messages

The message center information can be selected through the TRIP/RESET button (base cluster) and by the INFO, SETUP, and RESET buttons (high series cluster).

Information Displays (Base Instrument Cluster)
The information displays are non-timed modes. The selected mode remains on until the driver presses a message center switch to change the mode, or until it is overridden by another mode. The information display modes are:
- Odometer/trip odometer, compass headings
- Distance to empty
- Average fuel economy
- Setup menu

Information Displays (High Series Instrument Cluster)
The information displays are non-timed modes. The selected mode remains on until the driver presses a message center switch to change the mode, or until it is overridden by another mode. The information display modes are:
- Odometer/trip odometer, compass headings, outside air temperature display (with dual electronic automatic temperature control)
- Distance to empty
- Average fuel economy
- Instantaneous fuel economy
- Fuel used
- Trip elapsed drive time
- Blank

Setup Displays (Base Instrument Cluster)
The setup displays are timed modes and terminate after a finite interval. Press the TRIP/RESET button to scroll through the SETUP MENU display sequence. If the TRIP/RESET button is not pressed within 4 seconds, the message center returns to the INFO MENU. The setup display modes are:
- AWD lock (vehicles equipped with traction control with roll stability control [RSC] only)
- System check
- Units (English/metric)
- Language
- Autolamp
- Autolock
- Auto-unlock
- Parking aid
- Oil life start value

Setup Displays (High Series Instrument Cluster)
The setup displays are timed modes and terminate after a finite interval. Press the SETUP button for the following displays:
- AWD lock (vehicles equipped with traction control with roll stability control [RSC] only)
- System check
- Units (English/metric)
- Language
- Autolamp
- Autolock
- Auto-unlock
- Running boards (if equipped)
- Easy entry/exit seat
- Parking aid
- Compass zone
- Compass calibration
- Oil life start value

System Check Displays
Selecting this function from the SETUP MENU causes the message center to cycle through each of the systems being monitored. For each of the monitored systems, the message center indicates either an OK message or a warning message for 2 seconds. For base instrument clusters, the TRIP/RESET button must be held down after pressing the TRIP/RESET button to cycle the messages through each of the systems being monitored. For high series instrument clusters, pressing the RESET control switch cycles the message center through each of the systems being monitored. The system check report is as follows:
- OIL LIFE RESET
- CHARGING SYSTEM
- WASHER FLUID
- DOOR AJAR
- EXTERIOR LAMPS
- BRAKE FLUID LEVEL
- PARK BRAKE
- FUEL LEVEL

System Warnings
The system warnings alert the operator to possible problems or malfunctions in the vehicle operating systems. The message center displays the last selected feature if there are no more warning messages. This allows the operator full functionality of the message center after acknowledgement of the warning message by pressing the RESET button and clearing the message. The warning messages are divided into 4 categories:
- They cannot be cleared until the condition is corrected.
- They reappear on the display 10 minutes from the reset if the condition has not been corrected.
- They do not reappear until an ignition OFF-ON cycle has been completed.
- They reappear if the condition clears then reoccurs within the same ignition ON-OFF cycle.

The warning displays that cannot be reset are:
- DOOR AJAR
- CLEAR OBJECTS BY PASS SEAT

The warning messages that reoccur after 10 minutes are:
- CHECK CHARGING SYSTEM
- FUEL LEVEL LOW
- PARK BRAKE ENGAGED
- CHECK BRAKE SYSTEM

The warning messages that display whenever the ignition switch is turned from the OFF position to the ON position are:
- CHECK PARK AID
- BRAKE FLUID LEVEL LOW
- CHECK HEADLAMP
- CHECK HIGHBEAM
- CHECK TURN LAMP
- WASHER FLUID LOW LEVEL
- OIL CHANGE REQUIRED
- ENGINE OIL CHANGE SOON

The warning messages that return after a condition has cleared then reoccurs within the same ignition ON-OFF cycle are:
- LIFTGATE/GLASS AJAR
- LOW TIRE PRESSURE
- TIRE MONITOR FAULT
- TIRE SENSOR FAULT
- TRAIN TIRES
- TIRES TRAINED
- TIRES NOT TRAINED

Outside Air Temperature Sensor (Base Instrument Cluster without Electronic Automatic Temperature Control [EATC])
The base instrument cluster receives the outside air temperature data from the outside air temperature sensor. This data is then displayed on the message center. The outside air temperature sensor is located on the radiator core support behind the front grill assembly and is fastened with a pin-type retainer. If equipped with a high series instrument cluster, the outside air temperature data from the outside air temperature sensor is displayed in the electronic automatic temperature control (EATC) module.

Compass
The compass heading is displayed as one of N, NE, E, SE, S, SW, W and NW in the message center display. The compass reading may be affected when you drive near large buildings, bridges, power lines and powerful broadcast antenna. Magnetic or metallic objects placed in, on or near the vehicle may also affect compass accuracy. The compass sensor module is mounted behind the interior rear view mirror.