Brief description of the main instrument unit
|
|
Brief description of the main instrument unit
|
The main instrument unit conveys information to the driver and functions as an information link between the P-bus and the I-bus.
The vehicle speed is essential information for many control modules. The rear left wheel sensor is used by ESP to obtain wheel speed information. MIU receives wheel speed information from the ESP control module via the P-bus. MIU converts the wheel speed information to vehicle speed and sends it on the buses.
The main instrument unit has its own diagnostics function and sets a diagnostic trouble code when a fault occurs.
The main instrument unit incorporates the following:
|
•
|
Coolant temperature gauge
|
|
•
|
Instrument and display lighting
|
|
•
|
Warning and indicator lamps
|
The main instrument unit receives information from its own sensors and from other systems. The control module processes the information for showing on the MIU display or for the control of instruments and lights. Certain information is transmitted on the bus.
The light sensor is built into the main instrument unit and is used to measure the light strength in the cabin. The value of cabin light strength is transmitted on the bus and is processed by the SID control module. The SID control module then transmits the cabin lighting value and the display lighting value on the bus. These values are then used for control of the light strength on the main instrument unit's indicator lamps and display.
The rear left wheel sensor sends wheel speed information to the ESP control module. The ESP control module sends, via the bus, the speed value to the main instrument unit which shows the current vehicle speed on the electronic speedometer
The main instrument unit control module stores the value of the distance travelled and shows this on the information display. The odometer in the information display contains a six-digit register which the control module continuously updates from 000000 to 999999 km (or miles). The trip meter contains a four digit register that starts at 000.0 and runs up to 999.9 km (or miles).
The tachometer is electronic and shows the current engine speed. The tachometer continuously receives bus information on the engine speed from the engine control module. The tachometer display in the range below 1100 rpm is damped to give a more stable display.
The fuel gauge gives the driver information on how much fuel is left in the tank. It consists of a fuel gauge in the main instrument unit and a level sensor in the tank.
When the fuel level is below 10 litres, the main instrument control module switches to fuel consumption monitoring. The information comes on the bus from the engine control module. This gives a more accurate display of the fuel level. The Fuel Reserve indicator lights when the fuel level is below 10 litres.
|
Coolant temperature gauge
|
The coolant temperature gauge gives the driver information on the engine coolant temperature. The information comes on the bus from the engine control module.
The engine control module (ECM) receives information on the current air mass/combustion from the mass air flow sensor. The information is transmitted on the bus to the main instrument unit which displays the engine loading on the car's electronic turbo meter.
|
Warning and indicator lamps
|
The main instrument unit contains the following lamps:
|
•
|
Oil pressure warning lamp, warns the driver when engine oil pressure is too low.
|
|
•
|
Charge warning lamp, indicates to the driver whether or not the generator is charging.
|
|
•
|
AIRBAG warning lamp, warns the driver when a fault has occurred in the airbag system.
|
|
•
|
Brake fluid warning lamp, warns the driver if the level of the fluid in the reservoir is too low or if a fault has occurred in the ABS system.
|
|
•
|
Handbrake warning lamp, tells the driver that the handbrake is on.
|
|
•
|
ESP OFF indicator lamp comes on when ESP has been disengaged or there is a fault in the system.
|
|
•
|
ABS warning lamp, lights up when there is a fault in the ABS system.
|
|
•
|
Xenon lamp indicator lamp, lights on a fault in the automatic headlamp adjustment system, found on cars with xenon lights.
|
|
•
|
Fuel reserve indicator lamp, the lamp lights up when the fuel level is below 10 litres.
|
|
•
|
CHECK ENGINE indicator lamp, warns the driver that there is a fault in the engine management system.
|
|
•
|
Direction indicator repeater lamps, right and left. Show when the direction indicators are on.
|
|
•
|
CRUISE indicator lamp, on cars with cruise control the lamp lights up when cruise control is engaged.
|
|
•
|
Lights-on indicator lamp, indicates that the headlamps are on.
|
|
•
|
Rear fog light indicator lamp, indicates that the rear fog light is on.
|
|
•
|
Main beam indicator lamp, indicates that the main beam is on.
|
|
•
|
Glow plug indicator lamp. Comes on when the glow plugs are connected on cars with diesel engines.
|
|
•
|
Indicator lamp, engine preheating on the SID, the display shows that the engine must be preheated, installed in cars fitted with a diesel engine.
|
|
•
|
Heater indicator lamp on, shows that the engine heater is activated.
|
The information display is a part of the main instrument unit and is located in the lower section of the speedometer. The information display is used by the SID control module which via the bus informs the main instrument unit as to what is to be shown on the display.
The following information can be shown on the information display:
|
-
|
Trip computer information
|
|
-
|
Odometer and trip meter
|
|
-
|
Information from the ACC
|
|
Indicators and warnings on the information display
|
|
-
|
ESP, shows when the ESP is active.
|
|
-
|
SPORT, indicates to the driver that the SPORT mode is active. This is fitted to cars with automatic transmission.
|
|
-
|
CHECK GEARBOX, warns the driver when there is something wrong with the automatic transmission.
|
|
-
|
SHIFT-UP, the symbol is displayed when it is advisable to change up to a higher gear (certain markets).
|
|
-
|
Selector lever position indicator, indicates the selected gear position on cars with automatic transmission.
|
|
-
|
Door indication, indicates if any of the doors or the tailgate is open.
|
|
-
|
Indicator lamp, engine preheating on the SID, the display shows that the engine must be preheated, installed in cars fitted with a diesel engine.
|
|
Instrument and display lighting
|
The main instrument unit control module adjusts the display and instrument lighting according to the light intensity in the cabin and the rheostat value set by the driver. This gives a good level of lighting for day or night driving.
