ATG - Eps Testing system Mode D'emploi Et Entretien page 7

Power steering parts
The 'connector 3' at the bottom right is used to make the diagnosis with CABLE
6-B, 6-C, 6-D according to the selected model. The LED
3 at the side will turn on when you will enable the external diagnosis.
In the following picture you can find an example of testing a Mazda 3.
ATG - Eps Testing system