Please, where is the diagnostics connector for.

If the car was sold in the U.S. The connector is always near the steering column.

The only diagram I have is this one I drew up for a Dodge truck. I'm only familiar with what is sold in the U.S. Every manufacturer had their own design up through 1995. The plugs were standardized beginning with the '96 models and look like this, except the corners are rounded. Most of the wires listed are also standardized but a few are left available for each manufacturer's individual needs. The standardization also dictates that placement be near the steering column.