Description of On-Board Diagnostics

PRINCIPLE OF OPERATION, DIAGNOSTICS

ISAT diagnostics
Communication between the MOTRONIC control module and an Intellegant Saab Tester (ISAT) scantool is possible via pin 55 (K lead) and pin 13 (L lead).
Communication via the K lead is two-way and accordingly consists of both input and output signals.

With the ignition switch in the DRIVE position, the voltage applied to pin 55 is about 8 V and Batt+ when the ISAT is connected.
The voltage applied to pin 13 is zero (0 V), regardless of whether the ignition is ON or OFF (the ISAT grounds pin 13 when the L lead is used to activate system functions).

The diagnostics socket is located underneath the dashboard on the driver's side of the car.

Flash Codes
To comply with legal requirements in the US market (OBD I), it must be possible for emission-related faults to be signalled by means of flash codes on the CHECK ENGINE lamp (MIL).

The connection (L lead) between pin 13 of the control module and the diagnostics socket is utilized to activate flash codes. For a list of available flash codes continue at "Lamp Flash Codes" at "System Diagnosis/Procedures/Diagnostic Charts/. Engine Control Systems