Initial Inspection and Diagnostic Overview

Diagnostic Functions

General
The control module has an integrated diagnostics system (the Volvo On-board Diagnostics (OBD)). The control module continuously monitors its own functions and the input and output signals in the system. By connecting the VCT 2000 to the data link connector (DLC), different types of data can be obtained, such as diagnostic trouble codes (DTCs) and the current values of read-off components etc.

The on-board diagnostic (OBD) system also allow components and functions to be activated using a VADIS/VIDA PC.

NOTE: If the seat cannot be operated or if the on-board diagnostic (OBD) system cannot be accessed, check to see if a button on the control panel is stuck in the depressed position.

Also try to repeat the procedure with the motor running. Battery supply must be at full voltage before the on-board diagnostic (OBD) system will work.

Diagnostic Trouble Codes (DTCs)
The control module will store a diagnostic trouble code (DTC) if it detects a fault. 23 diagnostic trouble codes (DTCs) can be detected. The control module can store up to 8 diagnostic trouble codes (DTCs) at the same time.

When a diagnostic trouble code (DTC) is stored, the values of a predetermined number of parameters are frozen. The positions of the control buttons or the value from a potentiometer where the fault occurred that are assumed by the control module can be read-off using the frozen values.

Every diagnostic trouble code (DTC) has a counter, counter 2. The counter records the number of operating cycles which have been fault-free since the diagnostic trouble code (DTC) was stored.

A cycle begins every time one of the buttons the control panel is activated. If the counter counts up when a control button is activated, the fault occurs at that moment. The function can be used to determine whether the fault is permanent or intermittent.

Diagnostic trouble codes (DTCs) can be read off after all DTCs have been read and the required remedial action has been taken. The seat must then be test run. Then re-read the diagnostic trouble codes (DTCs) to ensure that the fault has been remedied.

One diagnostic trouble code (DTC), PSL/PSR-424, is stored permanently however and cannot be erased.

Reading off the Volvo on-board diagnostic (OBD) system

General
Fault data and other information can be read off using the VADIS/VIDA PC connected to the data link connector (DLC) via the VST 2000. The VADIS/VIDA PC communicates with the control module via a standardized interface.

The data link connector (DLC) is located in the passenger compartment.

To activate communication with the seat control module the following conditions must be met:

Battery voltage must be above approximately 11 V

The ignition can be switched off.

Reading and erasing diagnostic trouble codes (DTCs)
This function allows stored diagnostic trouble codes (DTCs), counters and frozen values to be read off and erased.

Diagnostic trouble codes (DTCs) can only be erased after all diagnostic trouble codes (DTCs) have been read off at least once and the cause of the fault has been remedied.

When the engine control module (ECM) detects a fault, the values of certain parameters are frozen. These can be read off with the diagnostic trouble code (DTC).

Frozen values for the following parameters can be read off:
- The motors' position and speed (via potentiometers)
- The position of the buttons on the control panel
- Motors activated (forward/backwards) or not
- Supply voltage to control module.

Reading off input and output signals
This function allows the value of all the control module inputs and outputs to be read off:
- Supply voltage
- Control module relays (outputs to motors)
- Potentiometer's values
- Motor's speed
- Control panel buttons

Read off control module identification
The control module can be identified by reading off a code from the control module memory. This code contains the control module P/N and software version.