Principles of Operation: Notes

The instrument cluster is a hybrid electronic instrument cluster (HEC). The instrument cluster and the smart junction box (SJB) use a combination of hardwired circuitry and the standard corporate protocol (SCP) communication network to transmit and receive information. 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.
• whether the module which received the input controls the output of the feature, or whether it outputs a message over the SCP communication network to another module.
• which module controls the output of the feature.

When installing a new instrument cluster, it is necessary to upload the module configuration to the diagnostic tool. Following installation of the instrument cluster, download the module configuration from the diagnostic tool into the new instrument cluster. For additional information, refer to MODULE CONFIGURATION . The following items are configurable:

• base display
• low tire pressure warning
• brake system level
• safety belt minder
• overspeed warning
• enhanced door ajar warning display
• overhead display
• speedometer
• default language
• oil life
• oil life status and warning

The base and optional instrument clusters both contain gauges, indicator lamps, and warning lamps that are designed to provide the driver with system status and to alert the driver that certain conditions exist in the vehicle. The optional instrument cluster contains the message center and is located in the cluster. Gauges provide information to the driver indicating the status of systems. The systems that use gauges include vehicle speed, fuel level, engine coolant temperature, and engine RPM. Indicator lamps provide information to the driver of conditions that exist in the vehicle. The indicator lamps include the turn signal, low washer fluid level, traction control, and speed control. Warning indicator lamps provide information to the driver of conditions that could potentially alter vehicle performance. Examples of the warning indicators include the ABS, BRAKE, safety belt, air bag, and low oil pressure.

Each time the ignition switch is turned from OFF to ON, the charging system indicator, the low oil pressure indicator and the malfunction indicator lamp (MIL) prove out and remain on until the engine is started. The safety belt warning indicator proves out for 65 seconds, or turns off when the safety belt is buckled. The air bag indicator proves out for approximately 6-8 seconds while the following instrument cluster indicators and warning indicators prove out for approximately 3 seconds:

• ABS warning indicator
• low tire pressure warning indicator
• lamp out (base cluster only)
• door ajar (base cluster only)
• low fuel
• BRAKE system
• TRAC OFF (if equipped)
• TRAC ACTIVE (if equipped) (base cluster only)
• check fuel cap
• transmission malfunction
• low washer fluid level (base cluster only)
• fail-safe cooling warning indicator (base cluster only)