| Pos. | Spare Part No | Name |
| 1 | Anti-theft/double door lock module | |
| 2 | Radio/Road Communication System Module (from '99 model year) | |
| 3 | Trip computer module | |
| 4 | Instrument panel | |
| 5 | Airbag module | |
| 6 | Data Link Connector (DLC) | |
| 7 | Central Timer Module (CTM) | |
| 8 | ABS module | |
| 9 | Electronic Stability Program (ESP) module | |
| 10 | Additional heater | |
| 11 | Steering wheel position sensor | |
| 12 | Powertrain Control Module (PCM) |
Communication between modules is established using two different bus systems; the data link connector (DLC) forms the interface between the modules and the diagnostic system tester.
The SCP (Standard Corporate Protocol) data bus has two associated wires. Communication along these lines is established both between the modules themselves and between the modules and the diagnostic tester. Even if there is a break in one of the lines, a short circuit to ground or a short circuit to the power supply, communication between the modules and the diagnostic tester is maintained via the other line.
The data bus (ISO 9141) has one line. In case of a break, short circuit to ground or short circuit to the power supply, communication between the module and the diagnostic system tester is impossible.
The Data Link Connector (DLC) is a standard 16-pin connector that connects the communication lines (SCP and ISO 9141), the EEP-ROM line, and the power supply for the diagnostic system tester.
The steering wheel position sensor transmits the steering wheel angle value to the Electronic Stability Program (ESP) module and communicates with the Electronic Stability Program (ESP) module and the SCP data link connector.
The Electronic Stability Program (ESP) module controls the anti-lock brake system (ABS), the traction control system (TCS) and the stability control system. This module is connected to the PCM, the steering wheel position sensor and the DLC via a data bus (SCP). Connection to the DLC is also possible via a data bus (ISO 9141).
The ABS module with TCS controls the anti-lock braking system and the traction control system and is connected to the PCM and DLC via a data bus (SCP). Connection to the DLC is also possible via a data bus (ISO 9141).
The software of the ABS module without TCS differs from the software of the ABS module with TCS, but they are otherwise identical. This module is not connected to the data bus (SCP). The ABS module is connected to the DLC via the data bus (ISO 9141).
The vehicle is equipped with either an Electronic Stability Program (ESP) module or an ABS module (with or without TCS).
The Powertrain Control Module (PCM) controls all functions related to engine and exhaust management. This module communicates with the Electronic Stability Program (ESP) module, the ABS with TCS module, the instrument cluster and the DLC via the SCP data bus.
The instrument cluster is connected to the data link connector (DLC) and the PCM via the SCP data bus and includes the following components:
- Speedometer
- Tachometer
- Odometer
- Odometer
- Fuel level indicator
- Engine temperature gauge
- Various control and warning lights
The additional heater is a heating system device powered by the fuel system, which heats the coolant of the diesel engine cooling system at low outside temperatures. The additional heater is connected to the DLC via a data bus (ISO 9141).
The airbag module controls the driver and passenger airbags, the side airbags and the pyrotechnic seat belt tensioners. This module is connected to the DLC via a data bus (ISO 9141).
The Central Timer Module (CTM) is connected to the DLC via a data bus (ISO 9141) and controls the time-dependent functions of the following systems:
- Heated rear window and windshield
- Interior lighting
- Intermittent cleaning mode for front and rear wipers
- Front and rear windshield washers
- Seat Belt System Warnings
- Ignition Key Removal Lock
- Energy saving relay
- Sound warning signal
The anti-theft alarm/double door locking module is connected to the data bus (ISO 9141) and controls the following functions:
- Opening the trunk
- Opening the hood
- Central locking
- Double lock
- Radio remote control
- Anti-theft system
The additional alarm system module is connected to the DLC via a data bus (ISO 9141) and has the following functions:
- Windscreen washer fluid level low - warning light
- Trip computer
- Outdoor temperature display
- Ice warning
- Error code display
From model year 99 Ѕ: The radio/traffic information module is connected to the DLC via a data bus (ISO 9141) and includes the following elements:
- Radio, cassette player, CD player
- Cell phone
- Navigation and emergency call system
Communication between modules
The engine speed signal for the tachometer, the engine temperature signal for the coolant temperature display and the signal for the speedometer are sent by the PCM to the instrument cluster via the data bus (SCP).