Fault Tracing With Volvo System Tester Scan Tool (ST)

C. Fault tracing with Volvo System Tester Scan Tool (ST)

CA. General






Applications

The Volvo System Tester Scan Tool (ST) is an instrument used for fault tracing on the Motronic 4.3 SFI/DI system. The ST is used in most of the fault-tracinq procedures and it provides comprehensive information about the fault.

Communication with control modules

Connecting the ST to the vehicle's on-board diagnostic (OBD) system enables the instrument to communicate with Motronic 4.3 SFI/DI in two ways.

Firstly, it can communicate with the control module memory in serial mode. Apart from reading diagnostic trouble codes (DTCs), this enables the instrument to determine if the fault is intermittent or permanent, and to check if the signal causing the DTG is too high, too low or absent. Serial communication also enables the ST to read the values of various operational parameters (Monitor Test) and to memorise these values (Freeze Test).
The ST can also be used with the data link facility of Volvo Diagnostics in Diagnostic Test Mode (DTM) 3. The user does not notice which method of communication the ST is using other than that Volvo Diagnostics is slower.
Both types of communication are possible with the ignition on or the engine running, with the following exceptions:
Operation ot components (DTM 3) is only possible with the ignition on and engine off.






Function

The ST can read DTCs and display the values of input and output signals and adaptive values, and can interpret whether a fault is intermittent or permanent.
Since the ST reads directly from each control module memory, all values are represented exactly as the control modules themselves record them. This, together with the fact that the user does not need to encroach on the system, for example by disconnecting connectors for measurement purposes, makes fault tracing both faster and more reliable.

Control module identification

The ST identifies the appropriate control module by reading a code in the memory, enabling it to display the parameters for that particular module. For example, EGR parameters are not shown for an engine without EGR.
If the control module number cannot be coded by the Volvo System Tester, the user himself should select the type of control module.

Key functions






In most cases, the functions of the keys are as described below.

ENTER: Activates selected function and displays next menu.
EXIT: Displays a previous menu or interrupts a function.
YES/NO: Used to answer prompts and to add or delete parameters.
UP/DOWN ARROWS: Used to select menu options, e.g. to move the cursor or display text or values which are too long for the display window.

Pressing an undefined key will produce a long bleeping signal.