System overview
The DSA control module (1) needs data about the speed of all four wheels in order to detect wheel spin. This data is provided by the ABS control module (2). The data is transmitted continuously. The DSA control module is able to detect whether on or both of the drive wheels lose grip.
If wheel spin is detected, the DSA control module transmits a signal to the engine control module (ECM) (3) to reduce the torque. The engine control module (ECM) reduces the torque by shutting off one or more injectors (4) in different stages.
The engine control module (ECM) communicates with the DSA control module via three communication lines.
- The first communication line is used to transfer both speed (pulse frequency / one pulse per top dead center sweep) and engine load data. The engine load data is indicated by pulse width. Variations in the pulse width also provide additional data such as start, idling and transmission data.
- The second communication line transmits data about the position of the accelerator pedal (AP). A pulse is transmitted every 20th millisecond. The pulse is proportional to the given value.
- A third communication line is used for the transfer of data about torque reduction from the DSA control module to the engine control module (ECM). This pulse frequency is 5 milliseconds. Again it is the pulse width that provides the data.
The DSA system is switched on every time the engine is started.
The DSA system can be disengaged with the DSA switch (8) on the center console. The DSA system can be re-engaged by pressing the DSA switch again. Otherwise, the system is activated the next time the ignition is switched on.
The DSA warning lamp is on the dashboard (5). This warning lamp indicates the status of the DSA system.
- The DSA warning lamp is lit for 2 seconds after the engine is started. During this time, the integrated DSA diagnostic system checks that both the ABS control module and the engine control module (ECM) are OK.
- The DSA system is not working if the DSA warning lamp remains lit. The is either a system failure or the system has been switched off manually.
- If the DSA warning lamp flashes while driving, the system is active and reducing the engine torque.
Diagnostic trouble codes (DTCs) from the DSA system can be read off with VIDA. Connect VIDA to the data link connector (DLC) (6) via VCT 2000.