System overview

System overview

System overview, components

1.	Trionic, engine management system (430/589/600/608)

2.	TCM (Transmission Control Module), control module for automatic transmission (502)

3.	TC/ABS (Traction Control) (382)

4.	P bus (Powertrain bus)

5.	MIU (Main Instrument Unit) (540)

6.	I bus (Instrument bus)

7.	SID (Saab Information Display) (541)

8.	TWICE (Theft Warning Integrated Central Electronics) (632)

9.	ACC (Automatic Climate Control) (216)

10.	Audio system, main unit (353)

11.	CDC (CD changer) (355)

12.	PSM (Power Seat Memory) (357Dk)

13.	PMM (Power Mirror Memory) (611)

14.	DICE (Dashboard Integrated Central Electronics) (628)

15.	Data link connector (H16-5/445)

16.	Airbag (SRS) (331)

17.	ABS (Anti-lock Brake System) (547)

18.	SPA (Saab Parking Assistance) (630)

System overview, brief description

P bus and I bus in the Saab 9-5

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.