Principles of Operation
Instrumentation and Warning Chimes
Principles of Operation
NOTE: The Smart Junction Box (SJB) is also known as the Generic Electronic Module (GEM).
The Instrument Cluster (IC) is a hybrid electronic cluster that utilizes a microprocessor to control the gauge, warning chime and indicator functions. Data is sent to the IC over the High Speed Controller Area Network (HS-CAN) bus lines and through hardwired circuitry to individual components such as the oil pressure switch, the parking brake switch and the ABS module.
Instrument Cluster (IC)
IC Gateway Function
The IC acts as a gateway module by receiving information in one format and transmitting it to other modules using another format. For example, the IC receives the Four-Wheel Drive (4WD) data from the 4X4 control module over the HS-CAN and sends the 4WD status to the ABS module through hardwired circuitry. This enables communication with modules that are not on the HS-CAN.
IC Configuration
When installing a new IC, it is necessary to upload the module configuration to the scan tool. Following installation of the IC, download the module configuration from the scan tool into the new IC. Refer to Information Bus to carry out the Programmable Module Installation (PMI). It is also necessary to carry out a parameter reset procedure whenever a new IC or PCM is installed. Refer to Antitheft and Alarm Systems. Programming and Relearning Passive Anti-Theft System (PATS)
NOTE: The parameter reset procedure must be carried out on Passive Anti-Theft System (PATS) and non-PATS vehicles or a no-start condition may occur.
IC Prove-Out
The IC carries out a display prove-out to verify that all IC controlled warning/indicator lamps and monitored systems are functioning correctly within the IC. When the ignition switch is cycled to the RUN position with the engine off, the indicators illuminate to prove-out according to the following table:
Warning Chimes
The warning chimes are designed to provide the driver with an audio warning that acts as a supplemental alert. The only deviation from this strategy is the air bag chime which is used to alert the driver that the primary warning system (air bag warning indicator) does not operate. The IC controls all warning chimes except for the Belt-Minder(R), which is controlled by the Restraints Control Module (RCM).
Warning Chime Characteristics
Each warning chime has unique characteristics that help 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 prioritizes the chimes according to a preset hierarchy programmed into the IC software. When more than one chime request is received by the IC, 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.
Refer to the following table for a summary of the chime characteristics including the chime priority.
Safety Belt Warning Chime
The safety belt warning chime alerts the driver that the safety belt is unbuckled. The safety belt chime sounds when the driver safety belt is unbuckled and the ignition switch is turned from the OFF to the RUN or START position. The safety belt warning chime stops when the safety belt is fastened, when the ignition is switched to the OFF position or after the chime has sounded for 6 seconds.
Belt-Minder(R)
The Belt-Minder(R) is configurable. To configure with a scan tool, refer to Belt-Minder(R) Deactivating/Activating Service and Repair.
The Belt-Minder(R) feature supplements the current safety belt warning function and is enabled after the current safety belt warning is complete (65 seconds). The Belt-Minder(R) reminds the driver that the driver safety belt is unbuckled by intermittently sounding a chime and alternately illuminating the safety belt warning lamp in the IC once the vehicle speed has exceeded 5 km/h (3 mph). The Belt-Minder(R) remains active for 5 minutes from the time it is started. While activated, the Belt-Minder(R) chime and indicator flash and chime alternately from on for 6 seconds to off for 30 seconds.
If the vehicle speed drops below 5 km/h (3 mph), the Belt-Minder(R) chime completes the current 6-second sequence then stops sounding. During this time of suspension, the safety belt warning indicator continues to illuminate. Once the vehicle speed exceeds 5 km/h (3 mph), the chime begins again, restoring the Belt-Minder(R) to full function.
Door Ajar Warning Chime
When any door is ajar and the ignition switch is in the RUN position, the door ajar warning indicator is activated and remains on until all doors are closed. A one second warning tone sounds once any time the key is in the ignition switch and any door is opened.
Headlamp On Warning Chime
The headlamp on warning chime alerts the driver that the headlamps or parking lamps are on, the key is not in the ignition lock cylinder, and the driver door is opened.
Key-in-Ignition Warning Chime
The key-in-ignition warning chime sounds when the driver door is opened with the key in the ignition lock cylinder, and the ignition switch is in the OFF or ACC position. It continues to sound until the key is removed from the ignition lock cylinder, or the driver door is closed.
Air Bag Warning Chime
A redundant warning chime is provided by the IC when the air bag warning indicator is not operational. The IC monitors the internal circuitry and bulb for the air bag warning indicator. If the IC receives an air bag warning indicator on request from the RCM and the IC detects a fault internally, the IC sets DTC B1868 and sounds the chime.