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Here's a brief guide on how to connect to the CAN bus on a Trionic7 ECU.

CAN bus connection offers a fast and convenient way to read or flash the firmware in the ECU. However, keep in mind that there's a slight chance it may fail while writing the memory, especially if you're flashing in the car. When that happens, you end up with a dead ECU, which no longer responds to a CAN connection. The only way to revive it in this case is by using a BDM interface.

Related Links: ECUProject forums, T7Suite, T7Tool, SaabOpenTech.


Lawicel CANUSB seems to remain as the best (if not the only) CAN-USB adapter supported by the community right now. You can also try RS-232 devices, but you may be hard pressed to find a laptop with a serial port these days.
9-pin adapter

Next, you need a female 9-pin D-sub connector. You're only interested in two pins here: #2 (CAN low) and #7 (CAN high). I'm using white and green wires to match the colors of CAN low and CAN high leads on the instrumentation bus in the Saab.
Power cable

If you plan to connect to the ECU on the bench, you will also need to power it up. There are three pins each where you need to apply ground (#25, #47, #62) and +12V power (#1, #23, #43). I made this simple harness with insulated alligator clips.
Bench testing

Hook up both the power harness and the CAN harness (pin #19 is CAN low, #66 is CAN high). Attach a power supply. It may not hurt to have slighly more voltage - these 16V IBM ThinkPad AC adapters seem to work great. Once it's powered up, start your software and proceed with connecting to the ECU.
ACC unit harness

There is a number of locations in the car where you can access the instrumentation bus: the SID, the stereo, the ACC, the CD changer, etc. I chose to unplug the ACC panel since I can live without it while tuning.
In-car connection

Connect your green "CAN high" wire to pin #33 on the ACC harness, and your white "CAN low" wire to pin #34. Turn the ignition key, and enjoy a live connection to your ECU.
P.S. Perhaps it's time to clean the screen on my laptop ;]

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