Hi Juan,

to activate TCAS in 2d panel, go to the Navradiio-Subpanel. The lowest part of it, where the transponder code is set, has the TCAS swith onthe right where it reads STBY, XPNDR, TA ONLY TARA: Click a little right of it ant it will switch to TARA and you´ll get the TCAS on. In the lower NAV CRT you will then see the TA RA message.
Then go to the EICAS subpanel and click in the middle of the range selector (button on the left side) - you then will see the "Traffic" message on the NAV CRT.

To activate TCAS in the 3d panel it´s just the same.

Regards,
Werner