Description of On-Board Diagnostics

The Trionic ECM communicates with an Intellegant Saab Tester (ISAT) scan tool via pin 33. The communication is two-directional and thus involves both input and output signals.

The ISAT scan tool can communicate with Trionic with the ignition switched on and the engine running, but also for 15 minutes after the ignition has been switched off. Obviously no functions requiring a +15 or +54 supply can then be activated.