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Brief description of the SID

Brief description of the SID


The purpose of the SID is firstly to proved the driver with information and secondly to control the horn, instrument and display lighting, and perform calculations for the SID trip computer functions. It has its own diagnostic function and diagnostic trouble codes are generated when faults occur.

The SID receives information from its own sensors and switches as well as from other systems. The SID sends out certain information on the bus.

The SID has the following sensors:


• Outside temperature sensor

• Steering wheel controls

• Coolant level sensor

• Washer fluid level sensor

• Filament monitor, front lights

• Rheostat

• Interior light sensor


Outside temperature sensor

The temperature sensor supplies information to the SID about the current outside temperature.

Steering wheel controls

There are 7 control buttons on the steering wheel. One is used to activate the horn, the others to control the audio system. When a button is pressed, the SID reads a voltage level.

On cars without an audio system, only the horn button is fitted.

Coolant level sensor

The sensor detects low coolant levels and sends information to the SID when the level is low.

Washer fluid level sensor

The sensor detects low washer fluid levels and sends information to the SID when the level is low.

Filament monitor

The filament monitor monitors the function of the front headlamps and sends information to the SID.

Rheostat

The SID uses the current rheostat setting to control button and display illumination on the SID.

The rheostat value is transmitted on the bus for use in adjusting the control and instrument lighting.

Interior light sensor

The light sensor is integral with the SID and used to measure the light intensity in the passenger compartment. The SID uses the current light reading and rheostat value to determine the intensity of the display lighting.

The interior light reading is transmitted on the bus for use in adjusting the light intensity of the indicator lamps on the main instrument unit.

The display lighting level is output to the bus to control the light intensity of the displays.

Units and languages

The unit combinations and languages of the SID can be selected according to the market. The following combinations are available.

Unit combinations



Language

litres/100km + °C (24 hour)



Swedish

miles/gallon (US) + °F (12 hour)



English

miles/gallon (imp) + °F (12 hour)



German

miles/gallon (imp) + °C (12 hour)



French





Italian





Spanish



The units and language selected are output to the bus for use by other systems.

Sound

The SID has an integral speaker for acoustic signals for its own functions and the functions of other systems.

Trip computer

The trip computer in the SID is operated by the buttons under the display.

The computer is available in two versions, SID 1 and SID 2 with the functions shown in the table:

Functions

SID 1

SID 2

TEMP (outside temperature)

X

X

DTE (distance on remaining fuel).

X

X

FUEL (average fuel consumption)

X

X

SPD (average speed)

X

X

DIST (distance to destination)



X

ARRIVAL (arrival time)



X

ALARM (time alarm)



X

SPD W (speed warning)



X



Time

The SID contains a digital clock with the current time, date and month, which are always visible when the SID display is on. The year is included by not shown on the display.

The clock is adjusted manually but can also be adjusted by RDS time which the radio sends out on the bus.

CHECK messages

The SID can be used by all connected systems to show CHECK messages.

Service message

Service reminder showing when it is time for a service.

Audio display

The SID can be used to display radio, cassette and CD settings for the car's audio system.

Horn

The SID activates the horn when information has been received from the steering wheel controls.

Night Panel

The Night Panel function switches off the display and parts of the instrument lighting, and dims the button lighting.

The Night Panel information is output to the bus for use by other systems.

Engine off time

The SID calculates the length of time that the engine has been switched off. This information is used by the outside temperature function.

The time value is output to the bus to be used for the starting settings for the ACC, etc.

Important

The Service Manual does not cover the complete operation of the SID unit. More detailed information is given in the Owner's Manual.


P-Bus and I-Bus


All control modules in the Saab 9-5 are connected to the bus with the exception of ABS and SRS. For cars with Traction Control, the TC/ABS control module is connected to the bus.

The bus allows large quantities of data to be sent between the control modules on only two cables. The bus is divided into a Power train bus (P bus) and an Instrument bus (I bus).

Trionic, TCM and TC/ABS power train systems require fast data communication so that no noticeable delay occurs, e.g. for torque limitation when changing gears.

Trionic, TCM and TC/ABS are connected to the P bus, on which data transfer is ten times faster than on the I bus.

The P bus and I bus are connected to the MIU. The MIU is responsible for making information on one bus available to the other bus.

The diagnostic instrument is not connected directly to the bus but communicates via the DICE, one of the control modules connected to the I bus, and so has access to all control modules connected to the bus.

Vehicle speed data is important for many control modules. Since the ABS is not connected to the bus, the vehicle speed signal is sent on a separate lead from the ABS to the MIU. The MIU then sends the data over the busses. In cars with Traction Control, the TC/ABS sends vehicle speed data to the MIU via the P bus.