Diagnostic Functions

Diagnostic functions

General
The control module has an integrated diagnostic system, which continuously monitors its own system as well as the input and output signals.

Diagnostic trouble codes (DTCs)
A diagnostic trouble code (DTC) is stored if the control module detects a fault.
A malfunction that has been detected repeatedly during several driving cycles will permanently turn off the functions adaptive cruise control, collision warning, and brake assistance as well as store a diagnostic trouble code for this.
A permanently switched off system can only be reactivated by resetting DTCs in the Forward Sensing Module (FSM), Central electronic module (CEM), Brake control module (BCM) in the same operating cycle.
A driving cycle includes ignition on, that the vehicle speed goes above 20 km/h as well as ignition off.
If a fault occurs in the functions for adaptive cruise control, brake support in the event of the collision risk, Lane Departure Warning and Driver Alert Control functions, a fault counter counts up per function. If these counters, regardless of each other, reach a predetermined value below one and the same operating cycle, independent error flags are set in the monitoring logistics in the Central electronic module (CEM).
Permanent switching off of the functions results in diagnostic trouble codes (DTCs) being stored in the Forward Sensing Module (FSM), Brake control module (BCM), and in the Central electronic module (CEM). The diagnostic trouble codes (DTCs) must be erased from all control modules during an operating cycle to reset these error flags.

Reading and erasing diagnostic trouble codes (DTCs)
Stored diagnostic trouble codes (DTCs) can be read off and erased using this function.
Diagnostic trouble codes (DTCs) can only be erased once all the diagnostic trouble codes (DTCs) have been read off at least once.

Reading off input and output signals
This function can be used to continuously read off the status of the control module's input and output signals.
For more information about parameters, see Vehicle communication information in Specifications, other.

Activating components
This function can be used to activate components to check that they are working.
For more information on activations, see Vehicle communication information under Specifications, other.

Reading off the control module identification
The diagnostic tool identifies control modules by reading off a number of codes from the control module memory.
The codes contain the following information about the control module:
- hardware P/N (control module without software)
- hardware serial number (control module without software)
- software P/N
- diagnostic software P/N (part of the software).