Brief description of the main instrument unit: General: Notes

The main instrument unit conveys information to the driver and functions as an information link between the P bus and the I bus.

In the Saab 9-5, all the car's control modules are bus-connected apart from ABS. On cars with Traction Control, the TC/ABS control module is bus-connected and on cars with ESP, the ESP control module is bus-connected.

The vehicle speed is important information for many control modules. The left rear wheel sensor is used by ABS, TC/ABS or ESP for information on the wheel speed. As ABS is not bus-connected, the wheel speed signal is transferred via its own lead from the ABS to the MIU. The MIU processes the wheel speed information into the vehicle speed and sends out this information on the buses. On cars with Traction Control or ESP, the MIU receives the wheel speed information from the TC/ABS or ESP control module via the P-bus.

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:

• Control module
• Speedometer
• Tachometer
• Odometer/trip meter
• Fuel gauge
• Coolant temperature gauge
• Turbo boost gauge
• Instrument and display lighting
• Warning and indicator lamps