Diagnostic Functions

Diagnostic functions

General
The control module has an integrated diagnostics system, Volvo On-board Diagnostics (OBD). The control module continuously monitors its own functions and the input and output signals in the system. Various types of information can be obtained, such as the current values of read-off components etc., by connecting the VCT 2000 to the data link connector (DLC).
The on-board diagnostic (OBD) system also makes it possible to activate components and functions using a VIDA PC.

Note! If it is not possible to operate the seat or access the on-board diagnostic (OBD) system, check to see if a button on the control panel is stuck in the depressed position. Also try repeating the process with the motor running. Battery supply must be at full voltage before the on-board diagnostic (OBD) system will work. See Checking supply voltage Checking Supply Voltage.

On cars within chassis numbers 267000 - 273594 (4-door) and 171000 - 177545 (5-door) the control module diagnostic function is disconnected. The VIDA PC can only be used if the existing control module is replaced with a new one. The existing control module on cars within these chassis numbers normally functions correctly apart from the diagnostic function.
In a few cars within the above chassis numbers the diagnostic lead to the control module is disconnected. When installing a new control module the diagnostic lead must be connected to connector A (control module side) in order for communication with the VIDA PC to be possible.

Diagnostic trouble codes (DTCs)
If the control module detects a fault it will store a diagnostic trouble code (DTC). 23 different diagnostic trouble codes (DTCs) can be detected. Up to 8 diagnostic trouble codes (DTCs) can be stored in the control module.
When a diagnostic trouble code (DTC) is stored, the values of a number of predetermined parameters are frozen. By using the frozen values, the control module register of, for example, the position of the control buttons or the value from a potentiometer where the fault occurred, can be read off.
For each diagnostic trouble code (DTC) there is a counter that keeps track of the total number of fault-free cycles that have run since the diagnostic trouble code (DTC) was stored.
A cycle begins every time one of the buttons on the control panel is activated. If the counter is counting upwards when a control button is activated the fault is not occurring at that moment. This function can be used to determine whether the fault is permanent or intermittent.
Erase diagnostic trouble codes (DTCs) after all DTCs have been read off and the necessary repairs have been made. The seat should then be test operated and then diagnostic trouble codes (DTCs) should be read off to check that the fault has been remedied.
However one diagnostic trouble code (DTC), PSL/PSR-424, is permanent and cannot be erased.