Principles of Operation
Instrumentation, Message Center and Warning Chimes
Principles of Operation
NOTE: The Smart Junction Box (SJB) is also known as the Generic Electronic Module (GEM).
NOTE: When installing a new Instrument Cluster (IC), it is necessary to upload the module configuration to the scan tool. Following installation of the IC (Instrument Cluster), download the module configuration from the scan tool into the new IC (Instrument Cluster). Refer to Information Bus to carry out Programmable Module Installation (PMI). It is also necessary to carry out a parameter reset procedure whenever a new IC (Instrument Cluster) or PCM is installed. Refer to Antitheft and Alarm Systems. Programming and Relearning
The IC (Instrument Cluster) utilizes a microprocessor to control the gauge, indicator, message center and warning chime functions. Data is sent to the IC (Instrument Cluster) over the Medium Speed Controller Area Network (MS-CAN) and the High Speed Controller Area Network (HS-CAN) bus lines and through hardwired circuitry from individual components. The IC (Instrument Cluster) uses each input to output an action to the gauges or indicators.
It is very important to understand:
- where the input originates.
- all the information necessary in order for a feature to operate.
- which module(s) receive(s) the input or command message.
- does the module which received the input control the output of the feature, or does it output a message over the communication network to another module.
- which module controls the output of the feature.
Instrument Cluster (IC)
IC (Instrument Cluster) Gateway Function
The IC (Instrument Cluster) acts as a gateway module by receiving information in one format and transmitting it to other modules using another format. For example, the IC (Instrument Cluster) receives the vehicle speed data from the PCM over the HS-CAN (High Speed Controller Area Network), converts the data into an MS-CAN (Medium Speed Controller Area Network) message and sends (gateways) the message to other network modules such as the HVAC module, the Audio Control Module (ACM) and the SJB (Smart Junction Box). This enables network communication between modules that do not communicate using the same network (HS-CAN (High Speed Controller Area Network) or MS-CAN (Medium Speed Controller Area Network)).
IC (Instrument Cluster) Network Messages
The IC (Instrument Cluster) uses input messages from other modules to control the gauges, informational indicators and warning indicators over the communication networks. If a required message is missing or invalid for less than 5 seconds, the gauge or indicator that requires the message remains at the last commanded state based upon the last known good message. For example, if the brake status message is missing for less than 5 seconds and the brake warning indicator was ON, the indicator remains in the ON state until the next good message is received. If the message remains missing or invalid for greater than 5 seconds, the IC (Instrument Cluster) sets a U-code DTC and the output becomes a default action for the indicator or gauge. Each indicator or gauge utilizes a different default strategy depending on the nature of the indication. Refer to the normal operation descriptions located before each individual pinpoint test for further description of the default action specific to each indicator or gauge. If the messaged input to the IC (Instrument Cluster) returns at any time, the normal function of the gauge or indicator resumes.
NOTE: Whenever a network message is suspected as missing and confirmed by a missing message DTC (U-code), it is important to look for other symptoms that may also be present in the IC (Instrument Cluster) and throughout the vehicle. Once a DTC is set in the IC (Instrument Cluster), it may be helpful to review the complete message list available in Information bus to see what other modules also rely on the same message and run the self-test for those modules. If the message is missing from other modules, the same DTC may also be set in those modules. Confirmation of missing messages common to multiple modules may indicate that the originating module is the source of the concern or the communication network may be experiencing some problems.
IC (Instrument Cluster) Configuration
The IC (Instrument Cluster) contains items that are configurable. Configurable items include customer preference items, which can also be set with a scan tool. The remaining configurable items can be set only by the Programmable Module Installation (PMI) process or by using As-Built data.
IC (Instrument Cluster) Configuration Parameters
IC (Instrument Cluster) Prove-Out
The IC (Instrument Cluster) carries out a display prove-out to verify that all module controlled warning/indicator lamps and monitored systems are functioning correctly within the IC (Instrument Cluster). When the ignition switch is cycled to the ON position with the engine off, the indicators illuminate to prove-out according to the following table:
Information And Message Center
The message center is an integral part of the IC (Instrument Cluster) that receives and acts upon much of the same information that is input and used to operate the IC (Instrument Cluster) gauges, informational indicators, warning indicators and warning chimes. The message center is a 2-line display located in the center of the IC (Instrument Cluster). The message center electronic functions use both hardwired circuitry and the Controller Area Network (CAN) to display information.
Compass Display
The compass display (located in the Front Display Interface Module (FDIM)) receives battery voltage from the SJB (Smart Junction Box) fuse 14 (10A). The compass module (integral to the auto-dimming interior mirror) provides vehicle directional inputs to the Instrument Cluster (IC), which sends the compass information to the FDIM (Front Display Interface Module) over the Medium Speed Controller Area Network (MS-CAN).
The compass is capable of self-calibrating. This decreases the need to manually set the compass. If the compass is displaying a heading (and not displaying the CAL indicator), the compass is in auto-calibration mode. In this mode, the compass automatically calibrates for changes in vehicle magnetics over the life of the vehicle. This auto-calibration mode makes sure that the compass heading is always accurate.
If the compass displays the CAL indicator for an extended period of time (longer than 5 seconds), this indicates the compass has been placed in the manual calibration mode and therefore, requires manual calibration. The compass may temporarily display the CAL indicator if the vehicle characteristics have changed (car wash, collision or other factors), with the CAL indicator turning off after the vehicle characteristics have returned to normal.
NOTE: This procedure is only applicable to vehicles without navigation. For vehicles equipped with navigation, refer to Accessories and Optional Equipment.
Compass calibration/zone adjustment is controlled by the 7 and 9 buttons on the Front Controls Interface Module (FCIM), which provides access to the calibration and zone adjustment procedures.
Trailer Sway Message
The message center provides the trailer sway message to inform the driver that the current traction control event is due to trailer sway. If the ABS module determines that the trailer is causing the vehicle to sway, the traction control/stability assist indicator is turned on along with the TRAILER SWAY REDUCE SPEED message in the message center.
Warning Chimes
The IC (Instrument Cluster) uses inputs that are both hardwired to individual components and messages that are sent from the other modules over the HS-CAN (High Speed Controller Area Network) or MS-CAN (Medium Speed Controller Area Network) to control the warning chime functions.
Warning Chime Characteristics
Each warning chime has unique characteristics to identify and differentiate each warning chime. The warning chimes use volume, chime frequency, length of time the chime sounds and the number of chime tones to identify which chime is sounding. The IC (Instrument Cluster) prioritizes the chimes according to a preset hierarchy programmed into the IC (Instrument Cluster) software. When more than one chime request is received by the IC (Instrument Cluster), the most important chime sounds. If a lower priority chime is currently sounding, the higher priority request takes over and replaces the lower priority chime.
There are 3 different chimes as listed below:
- Repetitive
- Single tone
- Tick-tock
The following table provides a summary of the chime characteristics including the chime priority.
Instrument Cluster (IC) Chime Characteristics
Air Bag Secondary Warning Chime
The air bag secondary warning chime warns that the air bag warning indicator does not work correctly and that a Supplemental Restraint System (SRS) fault condition exists. The IC (Instrument Cluster) monitors the air bag warning indicator status internally. When a fault is present in the air bag warning indicator and the IC (Instrument Cluster) receives an air bag warning indicator on request from the Restraints Control Module (RCM), the air bag secondary warning chime sounds.
The air bag secondary warning chime inputs are:
- Ignition switch RUN/START status.
- Air bag warning indicator chime request communicated by the RCM (Restraints Control Module) to the IC (Instrument Cluster).
Belt-Minder(R)
The Belt-Minder(R) is configurable. To configure with a scan tool, refer to Belt-Minder(R) Deactivating/Activating Testing and Inspection.
The Belt-Minder(R) feature supplements the current safety belt warning function and is enabled after the current safety belt warning is complete. The Belt-Minder(R) reminds the driver that the driver or passenger safety belt is unbuckled by intermittently and simultaneously sounding a chime and illuminating the safety belt warning indicator in the IC (Instrument Cluster) once the vehicle speed has exceeded 9.7 km/h (6 mph). The Belt-Minder(R) remains active for 5 minutes from the time it is started. While activated, the Belt-Minder(R) chime provides a series of 6 chimes/safety belt warning indicator flash sequences consisting of a one-second chime tone and safety belt warning indicator on/off state. The Belt-Minder(R) chime and the safety belt warning indicator sound and flash for 6 seconds, then the chime stops and the safety belt warning indicator remains on for 30 seconds. The IC (Instrument Cluster) repeats the chime cycle for 5 minutes.
If the vehicle speed drops below 4.8 km/h (3 mph) once the Belt-Minder(R) chime has activated, the chime turns off and the safety belt warning indicator remains on. When the vehicle speed exceeds 9.7 km/h (6 mph) again, the Belt-Minder(R) chime resumes.
The IC (Instrument Cluster) also provides a toll booth feature which allows the driver or passenger to unbuckle their safety belt after the safety belts were initially buckled, providing 1 minute without warnings after the vehicle exceeds 9.7 km/h (6 mph) again with a safety belt unbuckled.
When a MyKey(TM) programmed key is in use, the driver cannot configure the Belt-Minder(R) off. Once the Belt-Minder(R) is activated, the Belt-Minder(R) continues to chime periodically (does not time out after 5 minutes) and the audio system is muted until the driver and passenger safety belts are fastened. Refer to Antitheft and Alarm Systems for more information on the MyKey(TM) feature.
The Belt-Minder(R) warning chime inputs are:
- ignition switch RUN/START status.
- driver or passenger safety belt warning chime request communicated by the RCM (Restraints Control Module) to the IC (Instrument Cluster) through the HS-CAN (High Speed Controller Area Network).
Door/Liftgate Ajar Warning Chime
The door/liftgate ajar warning chime warns that a door is open or not fully closed. The chime sounds when any door, or the liftgate becomes ajar while the ignition switch is in the ON position.
The door/liftgate ajar warning chime stops sounding and resets when all the doors and the liftgate are closed, or the ignition lock cylinder is placed in the OFF/LOCK or ACC position.
The door ajar/liftgate warning lamp/chime inputs are:
- Ignition switch RUN/START status.
- Door ajar data communicated by the SJB (Smart Junction Box) to the IC (Instrument Cluster) through the MS-CAN (Medium Speed Controller Area Network).
Headlamps On Warning Chime
The headlamps on warning chime warns that the headlamps are on when the driver door is ajar and the key is removed from the ignition lock cylinder. The headlamps on warning chime sounds if the driver door is ajar, the headlamp switch is in the PARK or HEADLAMP position, and the key is removed.
The headlamps on warning chime stops sounding when any one of the above conditions are removed.
The headlamps on warning chime inputs are:
- Ignition switch position to the SJB (Smart Junction Box).
- Key-in-ignition switch position to the SJB (Smart Junction Box).
- Door ajar input from the driver door ajar switch to the SJB (Smart Junction Box).
- Headlamp switch input to the SJB (Smart Junction Box).
- Headlamps on chime request communicated by the SJB (Smart Junction Box) to the IC (Instrument Cluster) through the MS-CAN (Medium Speed Controller Area Network).
Key-In-Ignition Warning Chime
The key-in-ignition warning chime warns that the key is still in the ignition lock cylinder when the driver door is ajar. The key-in-ignition warning chime sounds when the driver door is ajar, the key is in the ignition lock cylinder and in the OFF/LOCK or ACC position.
The key-in-ignition warning chime stops sounding when the driver door is closed, the key is removed from the ignition lock cylinder, or if the ignition switch is turned to the ON position.
The key-in-ignition warning chime inputs are:
- Ignition switch RUN/START status.
- Key-in-ignition switch position to the SJB (Smart Junction Box).
- Door ajar input from the driver door ajar switch to the SJB (Smart Junction Box).
- Key-in-ignition chime request communicated by the SJB (Smart Junction Box) to the IC (Instrument Cluster) through the MS-CAN (Medium Speed Controller Area Network).
Message Center Warning Chime
The message center warning chime feature is to draw the driver's attention to the message center display to view each new warning message. The IC (Instrument Cluster) provides a single one-second tone whenever a new warning message is displayed in the message center. If multiple warning messages are present, the IC (Instrument Cluster) sounds a chime for each of the warning messages that are present.
Parking Brake Warning Chime
The parking brake warning chime warns that the parking brake is engaged when the vehicle is in motion. The parking brake warning chime sounds if the ignition switch is in the ON position, the parking brake is engaged, and the vehicle speed is greater than 4.8 km/h (3 mph).
The parking brake warning chime stops sounding if the parking brake is released, the ignition switch is not in the ON position, if the vehicle speed is less than 4.8 km/h (3 mph), or after 90 seconds from the time the chime is activated.
The parking brake warning chime inputs are:
- Ignition switch RUN/START status.
- Parking brake switch status communicated by the SJB (Smart Junction Box) to the IC (Instrument Cluster) through the MS-CAN (Medium Speed Controller Area Network).
- Vehicle speed data communicated by the PCM to the SJB (Smart Junction Box) through the MS-CAN (Medium Speed Controller Area Network).
- Parking brake warning chime request communicated by the SJB (Smart Junction Box) to the IC (Instrument Cluster).
Safety Belt Warning Chime
The safety belt warning chime warns that the safety belt is not fastened. The safety belt warning chime sounds when the driver safety belt is not fastened and the ignition lock cylinder is turned from the OFF/LOCK or ACC to the ON or START position.
The safety belt warning chime stops sounding when the safety belt is fastened, when the ignition switch is turned from the ON or START position to the OFF/LOCK or ACC position, or when the chime has sounded for approximately 6 seconds.
The safety belt warning chime inputs are:
- Ignition switch RUN/START status.
- Driver safety belt warning chime request communicated by the RCM (Restraints Control Module) to the IC (Instrument Cluster) through the HS-CAN (High Speed Controller Area Network).
Service AdvanceTrac(R) Warning Chime
The service AdvanceTrac(R)warning chime warns that the ABS module has detected a fault condition in the AdvanceTrac(R) system. The SERVICE ADVANCETRAC(R) message is also displayed along with the chime.
The service AdvanceTrac(R) chime sounds for approximately 2 seconds after an initial delay of 8 seconds following key ON. The AdvanceTrac(R) chime stops sounding when the ignition switch is turned from the RUN/START position to the OFF/LOCK or ACC position or when the fault condition is repaired.
The service AdvanceTrac(R) warning chime inputs are:
- Ignition switch RUN/START status.
- Service AdvanceTrac(R) warning chime request communicated by the ABS module to the IC (Instrument Cluster) through the HS-CAN (High Speed Controller Area Network).
Turn/Hazard On Tone
Since the turn/hazard flasher is an electronic function of the SJB (Smart Junction Box), the on/off sound that used to be present with standard bi-metal flashers is no longer present. To provide an audible sound and indicate that the RH/LH TURN or HAZARD indicators are on, the IC (Instrument Cluster) provides a tick-tock tone along with the visual turn signal indicators.
The turn/hazard on tone inputs are:
- Left turn indicator signal from the SJB (Smart Junction Box) to the IC (Instrument Cluster) through the MS-CAN (Medium Speed Controller Area Network).
- Right turn indicator signal from the SJB (Smart Junction Box) to the IC (Instrument Cluster) through the MS-CAN (Medium Speed Controller Area Network).
Turn Signal Left On Warning Chime
The turn signal left on warning chime warns that the turn signal has not been cancelled. The turn signal left on warning chime sounds if the left or right turn signal is on and the vehicle has traveled more than 3.2 km (2.0 miles).
The turn signal left on warning chime stops sounding if the turn signal is turned off, or if the ignition lock cylinder is turned to the OFF or ACC position.
The turn signal left on warning chime inputs are:
- Ignition switch position to the IC (Instrument Cluster) and SJB (Smart Junction Box).
- Turn signal on data communicated by the SJB (Smart Junction Box) to the IC (Instrument Cluster) through the CAN (Controller Area Network) communication.
- Odometer count data communicated by the PCM to the IC (Instrument Cluster) through the HS-CAN (High Speed Controller Area Network).