Description of On-Board Diagnostic System

Notes on the BMW DIAGNOSTIC SYSTEM:

*D* Status Lists:

In contrast to the text message in the instrument cluster display, the diagnostic program indicates the status of the signal generator systems without any additional condition (e.g. engine speed, vehicle speed).

The diagnostic program only takes into account the maximum equipment level on the vehicle. If not installed, the corresponding signal generator systems must be displayed as "OK".

Simulation of the Speed (Tacho) Signal:

Simulation is not possible via the diagnostic program

Note the following during simulation of the speed (tacho) signal by way of frequency input:

- Only restricted use of the BMW Service Tester *M* Frequency OFF is possible. The speedometer function can be checked, no mileage reading, no speed-A output signal, no vehicle speed display in the BMW DIAGNOSTIC SYSTEM.

- The use of the BMW simulator for the instrument cluster is possible without restrictions. Connect 25-pin bypass connector for frequency simulation to the simulator. Connect simulator to vehicle battery. A continuously variable frequency can be entered via the frequency output (yellow socket).

The screen displays for vehicle speed and engine speed deviate from the instrument displays. Reason: Advance setting of instruments.

Troubleshooting:

Notes:

- Troubleshooting with the BMW DIAGNOSTIC SYSTEM
- Battery charged, U-min = 12 V
- If EML is installed: The defect code memory of the EML control unit is cleared when the connector 3 (X502, color white) is removed. Always monitor the EML defect code memory beforehand!
- Frequent installation and removal of the coding plug (X17, color brown) subjects the connection to unnecessary load. remove and carry out checks only when specified in the troubleshooting procedure. Never carry out measurements at the NV-RAM (black component in coding plug).
- Remove and install the instrument cluster, check control module and lamp control module only when the ignition is switched off.
- The plug-in connections can be very easily damaged when unsuitable measuring equipment is used. Therefore, only carry out checks at the connectors using the special adapter leads provided for this purpose.
- Take particular care when renewing indicator lamps to ensure that only replacement lamps with the specified ratings are used.