temp gauge

i just installed a temp gauge and a new sending unit and it dosenot work is their a way to check the gauge with a tester ( this is a used gauge ) or not. i went though a made sure that all connections are clean and making good connection,i also disconnected the dummy light. any suggestions ? the gauge light is the only thing i have working, is it posable that the wires in the plug for the gauge are mixed up maybee from the preveus owner, and can anyone give me the combo of what color wires go from plug to plug just to make sure i have all the right wires going to the right one.

thanks mark