SAS Diagnostic Functions: Notes

Fig 1: Control Module For Steering Wheel Angle Sensor

Courtesy of VOLVO CARS CORPORATION

General

The control unit has built-in diagnostics, Volvo Diagnostics, which continually monitor the unit and the input and output signals.

Diagnostic trouble codes

If the control unit detects a fault, it stores a diagnostic trouble code. If, for any reason, a fault disappears after the diagnostic trouble code has been permanently stored in the control unit, information about the trouble code still remains in the control unit.

Reading and erasing diagnostic trouble codes

Stored diagnostic trouble codes can be read from the control unit using this facility.

Diagnostic trouble codes may be erased but only after they have been read at least once.

Reading input and output signals

Status of control unit input and output signals can be continually read using this facility.

For more information about parameters, see DESCRIPTION OF PARAMETERS (STEERING ANGLE SENSOR) .

Reading the control unit identity

VIDA identifies control units by reading the number of codes from the control unit memory. The codes contain information on the control unit as follows:

hardware component number (control units without software)
software component number (control units without software)
software component number
diagnostic software component number