Principles of Operation

PRINCIPLES OF OPERATION

The instrument cluster (IC) is a configurable, hybrid electronic cluster (HEC) that contains a microprocessor, gauges, indicator lamps, and internal circuitry. The instrument cluster (IC) is non-repairable with the exception of the instrument cluster (IC) lens and indicator bulbs. The instrument cluster (IC) uses hardwired circuitry, the controller area network (CAN) and the universal asynchronous receiver transmitter (UART)-based protocol (UBP) communication networks. Communication using the CAN transmits and receives data between the instrument cluster (IC), the PCM, and the ABS module. Communication using the UBP network uses data transmitted and received by the instrument cluster (IC), the HVAC module, vehicle security module (VSM), and the driver seat module. The restraints control module (RCM) and the parking aid module communication is on the international standards organization (ISO) network.

The instrument cluster (IC) utilizes a microprocessor to control the gauge and indicator functions. Data is sent to the instrument cluster (IC) over the high speed controller area network (HS-CAN) bus lines and through hardwired circuitry from individual components. The instrument cluster (IC) uses each input to output an action to the gauges or indicators.

It is very important to understand:
- where the input originates from.
- 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 communication network to another module.
- which module controls the output of the feature.

Integrated Circuit Display

NOTE: On vehicles equipped with electronic automatic temperature control (EATC), the HVAC module displays the outside air temperature. The instrument cluster (IC) only displays the outside air temperature on vehicles that are not equipped with EATC.

In addition to the compass, outside air temperature and odometer/trip odometer, the integrated circuit display provides the driver with information using a text-based format. The CHECK GAUGES display illuminates when there is low oil pressure, high engine coolant temperature or when the vehicle has entered into the fail-safe cooling mode.

Instrument Cluster Configuration
The instrument cluster (IC) contains items that are configurable. While some configurable items are customer preference items, most items are configured at the end of the line production and only available for configuration using As-Built data. Refer to Information Bus (Module Configuration) for information on module configuration.

The configurable instrument cluster (IC) customer preference items are as follows:
- Autolocks (message center cluster)
- Outside air units
- Belt-Minder(R)

Instrument Cluster Prove-Out
The instrument cluster (IC) carries out a display prove-out to verify that the warning/indicator lamps and monitored systems are operating correctly. When the ignition switch is turned to the ON position, the charging system warning indicator and the malfunction indicator lamp (MIL) illuminate until the engine starts and is running normally. The safety belt warning indicator proves out for 6 seconds or until the safety belt is fastened. The door ajar warning indicator illuminates only with the key in the START/RUN position and one or more doors are open, turning off only when the doors are closed. When the ignition switch is turned to the ON position with the engine off, the following indicators illuminate for approximately 3 seconds with the exception of the air bag warning indicator, which illuminates for approximately 6 seconds:
- ABS warning indicator
- BRAKE warning indicator
- 4x4 high indicator
- LOW RANGE indicator
- Electronic throttle control (ETC)
- Traction control indicator