Description of On-Board Diagnostic System

Notes on the BMW DIAGNOSTIC SYSTEM:

*D* Component Activation:

Acoustic Relay:

The acoustic relay is activated with a fixed frequency.

Speed Signal Simulation:

An arbitrary vehicle speed or frequency can be specified. The vehicle speed is indicated in the speedometer and transferred to other control units in the form of a speed-A signal.

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 defect code unit (e.g. DME), and this is caused by a faulty speed-A signal, then the defect code must be
cleared.

*D* Test Procedure:

Display of input status's with notes on troubleshooting.

*D* Special Functions:

- Output of important coding data.
- System test activation

Troubleshooting:

Notes:

- Troubleshooting takes place mainly in accordance with instructions in the BMW DIAGNOSTIC SYSTEM
- Battery charged, U-min = 12 V
- The plug connections can be very easily damaged when unsuitable measuring equipment is used. Therefore only carry out checks at the plug connections 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.