Description of On-Board Diagnostic System

Notes on the BMW DIAGNOSTIC SYSTEM:

Following control unit identification, the following branches listed below are made available:

*D* Status lists: Check-Control:

- In contrast to the text message in the instrument cluster display unit, the diagnostic program indicates the status of the sensor systems without the necessity for additional operation (e.g. engine speed, vehicle speed).
- Automatic defect detection and defect evaluation when the text message "CHECK CONTROL" appears in the instrument cluster display unit.

Identification of the systems with "*", which triggered a check-control message during past vehicle operation.

*D* Status lists: Instrument Cluster:

- Output of important coding data.
- Monitoring of important inputs of the instrument cluster.
- Defect detection break/short of all temperature sensors and the immersion tube sending unit.

*D* System Test:

- Internal system test is activated.

*D* Speed Signal Simulation:

- Any arbitrary vehicle speed or frequency can be specified. The road speed is indicated in the speedometer and transferred to the other control units in the form of a speed-A signal.
- High frequency or speed values are transferred by the BMW Service Tester in steps (2 to 3 part steps) to the instrument cluster.
- Simulation is terminated automatically after 60 seconds.

Important!

Various control units store defect codes when the speed signal is simulated. Therefore, a . D. quick test must be performed after each simulation of the vehicle speed signal. If a defect code is stored in a control unit (e.g. DME, EML) and this is caused by a faulty speed-A signal, then this defect code must be cleared (.D.999).

*D* Activate Gong:

The gong is activated.

*D* Defect Code Memory:

All defect codes which occur in the area of the coding plug are stored in the defect code memory.

*D* Clear Defect Code Memory:

Clearance of the defect code memory and the "*" identifier in the status lists check-control.

*D* Read Out Engine Test Code:

In the case of all type of engine and clutch damage in vehicles with the 538 B36 engine (model M5), the engine test code must be printed out and accompanied with the warranty or goodwill application. The engine test code contains engine and vehicle data.