Main instrument unit: Description

The main instrument unit is used to convey information to the driver by means of gauges, display information and indicator and warning lamps.

The main instrument unit receives information from other control modules via bus messages on the I-bus. The control module processes this information and controls the gauges, display and warning and indicator lamps internally, except for the check engine lamp, which is controlled by the engine control module ECM when it grounds the lamp.

The gauge needles are each controlled by a stepping motor. The instrument graduations, needles, indicator lights and display are illuminated by means of LEDs.

The control modules transmit some bus information, e.g. the mileage and filtered fuel level.

The main instrument unit has its own diagnostic function and sets a diagnostic trouble code in case of a fault.

The main instrument unit incorporates the following:

• Speedometer
• Odometer/tripmeter
• Tachometer
• Fuel level gauge
• Coolant temperature gauge
• Turbo boost gauge
• Warning and indicator lamps
• Main instrument unit display
• Instrument and display lighting

The main instrument unit carries out calculations for the following functions:

1. Fuel level
2. Sums up and stores driven distance