You need the 2 wire SCS connector. Jumper the terminals with a wire or a paper clip, turn the ignition key on, read flash codes from the CEL. Standard 2 digit format.
My pic shows it as near the glovebox somewhere under that side of the dash. Some are taped to the ECM harness up kind of high, some are stuck in their own little holder, some are stuck under the beam below the glovebox.
There is a 3 wire connector nearby that is only for the Honda compatible scantool, you can't use it for anything else.