Diagnostic Functions

Diagnostic Functions:

Read Defect Code Memory:

The majority of control units are capable of automatically detecting a defect and to store it permanently. The contents of the defect code memory can be read out with the BMW DIAGNOSTIC SYSTEM.

Additional information is, in part, also stored when a defect code is stored. This additional information indicates the operating conditions under which and how often the defect occurred.

More extensive troubleshooting is then carried out in accordance with the instructions provided in the diagnostic program or in the Testing and Inspection procedures section at the system/component level.

The "Notes on the BMW DIAGNOSTIC SYSTEM and Troubleshooting" provide detailed information on how and under what circumstances the relevant control unit detects a defect and its significance.
Description of On-Board Diagnostic System

Important!

On no account clear the defect codes before repair, otherwise important information (troubleshooting, additional information etc.) will no longer appear on the display screen.

Clearing Defect Code Memory:

The defect code memory must be cleared after all defects of a system have been rectified.

Test Code:

The test code must be printed out before renewing a control unit or an important component of the system. The test code contains the coded defect code memory of the control unit.

Important!

Print out test code before the defect code memory is cleared!

Status Monitoring:

With this function, it is possible to read out current statuses and values applied at the inputs and outputs of the control unit. This display must be compared with the actual status on the vehicle and its plausibility must be checked.

If a signal is found to be defective or if the status detected by the control unit deviates from the actual status on the vehicle, troubleshooting must be carried out at the input or output concerned. In the majority of cases, a defect can then be localized by simple measurement (voltage, resistance etc.).

Test Procedure:

- only in the diagnostic program Of the BMW SERVICE TESTER -

This function makes it possible to perform a guided check of the system. The test procedure incorporates status monitoring, component activation and, if necessary, also reading the defect code memory. The display screen pages contain detailed information texts on testing and troubleshooting.

Component Activation

With this function, components can be activated without the control unit-internal switch-on conditions being set. The actual statuses at the inputs of the control unit are ignored. In this way, the function of components can be checked while they are still installed in order to locate defects.

Special Functions

Special control unit functions can, in part, be called up via the diagnostic procedure (e.g. system test, reading out coded data etc.).

Note:

Important information on the control unit or on the diagnostic procedure can be called up from any screen page by way of the note button.

Note button:

# on BMW Service Tester

C on BMW MoDiC