Putting a new wiring harness in my 82 Sierra. Has heat only, no ac. My problem is the original plug that went into the bottom of the blower relay is missing and I'm not sure how to hook it up. All the wires on the new harness already have connectors crimped on to plug on each individual prong but without being able to see the way the wires went into the back of the original plug for the color reference, I don't know which wire goes where. Any ideas?