Saab 9-5 MY 2004

Electrical, Lighting and Audio Systems

Highlights:

* Data bus electronic control and diagnostic system
* Optimised headlamps with bi-xenon bulbs
* High pressure six-jet screen wash/wipe system
* Bespoke audio systems
* DVD-based satellite navigation

Digital connections
The Saab 9-5 is fitted with two advanced data bus systems which communicate information within the vehicle via a digital network of only two wires instead of many different wiring circuits and harnesses. This technology saves weight, complexity and cost, as well as providing more reliable and robust connections.

Engine temperature data, for example, which might be needed by several different processors, can be sent around the system and updated continuously as a single message packet, instead of each system independently gathering its own information signal from its own dedicated sensor.

In the new Saab 9-5 there is an instrument panel bus (I-bus), which connects the main fascia instrument display with the automatic climate control module (ACC), the theft warning module, the audio head unit, the CD changer and the Saab Information Display (SID) and, when fitted, the power seat memory module and the driver memory module (for the mirrors)

The I-bus is linked by a selective gateway to the powertrain bus (P-bus) for Saab’s own Trionic engine management system and the automatic transmission control module (TCM). The ABS and Traction Control System (TCS) are linked separately to the Main Instrument Unit (MIU). Vehicle road speed signals, for example, are obtained from the ABS controller, which is separate from both bus circuits, and sent to the main instrument unit which then transmits it to the data buses.

These two Controller Area Networks (CANs) allow all parts of the systems to talk to each other on a ‘need to know basis’ at extremely high speed, enabling them all to access the same data and interact very rapidly when necessary. The P-bus runs at 10 times the speed of the I-bus because the engine and transmission require updated real-time information much more quickly than the other systems. It has been developed with the capacity to transmit data at up to one million bits/sec (about 100 times the speed of a fax machine and 35 times the speed of the latest V34 modems).

Information is only transmitted between the two bus systems on a selective basis because data that is relevant to only one part of the system, such as engine torque for the P-bus, or the lighting rheostat level for the I-bus, is best contained within its own network.

Complex surface headlamps with bi-xenon option
It was a deliberate decision to keep the headlamps of the Saab 9-5 relatively large. This has allowed lighting engineers to increase the efficiency and output of the units by 25 per cent rather than maintain the previous performance levels with a smaller housing.

Behind the clear plastic, scratch-resistant lenses, ‘complex surface’ reflectors are designed so that each small part of the reflector’s surface is treated as a separate element, directing light to a specific part of the road ahead.

Twin halogen H7 bulbs, are fitted in each unit and arranged so that the high beam supplements the low beam, which stays illuminated at all times. The bulbs incorporate a darkened cap to reduce glare for other road users on high beam, which is disturbing when driving at night in bad weather conditions (such as rain, snow or fog).

Xenon bulbs use a gas discharge, instead of a glowing filament, to produce a searing, white beam that is twice as powerful as that emitted from a conventional halogen bulb. Saab is one of the first car manufacturers to adopt this technology. And for the 9-5, Bi-xenon lighting is available as an option and uses a single xenon bulb and projector unit to provide a high and low beam by raising or lowering a shutter in front of the bulb. It is used together with a conventional high beam-only halogen bulb and the resulting spread of light is about 60 per greater than the 9-5’s exemplary all-halogen set-up.

Auxilliary lighting
Front fog lamps are integrated in the lower front bumper mouldings and the tail lamps have large lens areas and illumination levels that exceed all legal requirements by a generous margin. They are well separated and supplemented by a third central high-mounted rear brake light.

Car entry ‘puddle’ lights are mounted in the bottom of the front doors, so they show the ground as soon as a door is opened. Interior floor and overhead lighting for each seating position dims progressively when switched off via the automatic, delayed-action timer. To protect the battery from discharging, any lights left on inadvertently by the driver are turned off automatically 20 minutes after leaving the car.

Powerful six jet washer system
A battery of three double screenwasher jets provide six powerful sprays that rapidly cover the entire windscreen. They are operated by an integrated wash/wipe stalk control and use exceptionally high pressure - 3.0 bar instead of the usual 1.8 bar - to provide a high-velocity flow from the large 6-litre reservoir. The washer system has been developed to provide extremely efficient performance, particularly at higher speeds or in low temperatures.

The wipers have two fixed speeds and a variable intermittent feature. Their arms have been developed in the Saab climatic wind tunnel to keep the blades firmly on the glass, even at maximum speed.

A separate pump supplies water from the same reservoir as the ‘pop up’ headlamp washer jets, which operate automatically whenever the windscreen is washed.

Advanced audio systems
The audio system has been carefully designed to match the interior acoustic characteristics of the 9-5 sedan and wagon. There are three systems, all with steering wheel mounted controls and an aerial integrated into the rear window.

The entry level system (AS1) is based around a high quality CD/FM/AM RDS tuner with traffic announcement and programme facilities as well as ‘best signal’ selection. Frequency, station identity and program information are shown in the Saab Information Display (SID). This system plays through four 15-watt full-range speakers located in the instrument panel and rear doors. Those in the front are 86 mm diameter and those in the rear doors 123 mm diameter.

Main switch controls and push buttons are located in the centre console above the climate control system. Controls for the most frequently used functions - volume, audio source, seek and selection of preset stations - are repeated on either side of the airbag housing in the centre of the steering wheel, within an easy thumb-stretch of the rim.

The next level up (AS2) additionally incorporates a tape cassette function and a larger amplifier with up to 125 watts of output. It plays through a total of seven speakers, with two additional ones being added to the front doors and a central 61 mm dia. unit in the facia to improve the sound stage effect. This gives the listener the feeling of sitting in front of an orchestra

The top-of-the-range system (AS3), using components supplied by Harman Kardon, has a power amplifier uprated to 175 watts and two oval sub-woofer speakers (152 x 289 mm) added to the rear parcel shelf.

All systems feature a ‘smart’ speed sensitive, volume control which automatically compensates for the inevitable slight increase in ambient noise levels as road speed increases. In the latest equipment, the degree of compensation is related to the initial volume setting, relatively quiet settings being increased more than higher volume settings. Volume settings are automatically decreased as the speed reduces.

Satellite Navigation
A DVD-based navigation system, with a large 7.0-inch color screen integrated in the central console, can be specified in combination with the AS2 or AS3 audio systems. A DVD unit in the trunk allows cross-border route guidance throughout Europe without the need to make a disc change (not available for US market).