Check engine light and codes

I remember when I had my ranger someone had told me how to check the engine codes by connecting a test light to a connector or between two of them and grounding a terminal in the engine compartment by the heater blower motor. Can anyone tell me which ones to connect and ground? I found the 3 terminal and the single terminal connectors. Also I just started my truck to move it closer to the door at work and the check engine light came on, the idle was slightly erratic and it surged a bit when I first put it into gear, but the light went off after about four or five minutes of running when I revved the engine, I know it's about 5 below outside, but any Ideas?