System diagnosis, function - GF00.30-P-0001R

MODEL 230 

System diagnosis 

Continuous fault monitoring and localization while the vehicle is being driven is performed through the system diagnosis integrated in the vehicle.

The software of the system diagnosis is composed of

• the onboard knowledge base
• the evaluation software (diagnosis algorithm)

This is located as follows:

• Up to 31/10/2003  in the system diagnosis control unit (N55)
• As of 1/11/2003  in the central gateway control unit (N93)

During driving, information is transmitted as follows: Up to 31/10/2003  : All fault codes located at the CAN-Class B (Control Area Network Bus, Class B (interior)) control units and supplemental information are transmitted to the system diagnosis control unit (N55).

As of 1/11/2003  : All fault codes located at the CAN-Class B (CAN interior) and CAN-Class C (Control Area Network Bus, Class C (engine compartment)) control units and supplemental information are transmitted to the central gateway control unit (N93).

Using the information in the onboard knowledge base, the evaluation software determines which components are faulty.

Function prerequisites: 

• C. 30 ON
• Up to 31/10/2003:  To output faults, the Diagnosis Assistance System (DAS) must be connected by the K-line to the data link connector (X11/4).
• As of 1/11/2003:  To output faults, the STAR DIAGNOSIS system must be connected via the CAN diagnosis line (CAND) to the plug at the data link connector (X11/4).

Evaluation software 

The system diagnosis is based on the fault codes and supplemental information from the individual control units. If a control unit detects a fault, the associated fault code and supplemental information are transmitted as follows:

• Up to 31/10/2003:  To the system diagnosis control unit (N55)
• As of 1/11/2003:  To the central gateway control unit (N93).

The evaluation software can use the transmitted fault codes and process variables to categorize each electrical path:

• path faulty -> all components in this path are suspect
• path free of faults -> all components in this path are OK

The system diagnosis evaluation software can use this data to limit the number of error-active components.

Design and content of onboard knowledge base 

The onboard knowledge base contains information on the relationships between the fault codes, supplemental information and error-active components. The different variants, such as variants in special equipment, national versions and functions are stored in this onboard knowledge base and activated as appropriate for the specific vehicle.

Programming of onboard knowledge base 

The onboard knowledge base is programmed at the factory as follows:

Up to 31/10/2003:  In the system diagnosis control unit (N55)

As of 1/11/2003:  In the central gateway control unit (N93)

In certain cases, it is necessary for the control unit to be programmed in the workshop  :

• Failure of the system diagnosis control unit (N55) or the central gateway control unit (N93)
• When installing a new variant of a CAN-B or CAN-C control unit, which requires an update of the onboard knowledge base.

Display in diagnosis assistant system (DAS) (up to 31/10/2003) 

The results of the system diagnosis are read out and displayed in the Diagnosis Assistant System (DAS) under the "System Diagnosis - Interior Test" menu item.

Displayed in STAR DIAGNOSIS (as of 1/11/2003) 

The results of system diagnosis are read out and displayed under the "CGW" menu option.

The following information is displayed for each diagnosis result:

Up to 31/10/2003: 

• Diagnostic result, system diagnosis/fault code and error text
• Error-active component
• Vehicle function affected
• Test instructions

As of 1/11/2003 

• Control unit version
• Actual values
• Control unit adaptations
• Complete list of conducted tests
• Complete list of fault codes

Inspection instructions not yet resolved can be listed for the purpose of improving diagnosis result.

Starting at the error active components it is possible to branch off into the rest of the test sequence.

Additional functions 

• ATA alarm sources

  The system diagnosis stores the fault symptoms for the anti-theft alarm system (ATA) in code 551a.

  These error images provide indications on the cause of a triggered alarm.

• Actual and specified (nominal) configuration for the CAN Class B control units (up to 31/10/2003  )

  For each CAN Class B control unit, information is displayed indicating whether this control unit is supposed to be installed and whether it is currently active on the CAN data bus.

• Actual and specified configuration for CAN Class B and CAN Class C control units (as of 1/11/2003  )

  A comparison of the specified and actual configurations for the control units will indicate whether they are supposed to be installed and whether they are active in the CAN data bus.

  During this evaluation, two error cases are distinguished and displayed as a diagnostic result:

• CAN single-wire mode (control unit is active, but is sending in CAN single-wire mode)
• Control unit is not active

	System diagnosis control unit, location/task/design	Up to 31/10/2003	GF54.21-P-4119R
	Central gateway control unit, location/task/design	As of 1/11/2003	GF00.19-P-4100R
	Data link connector, location/task/design/function		GF54.22-P-2100R