Over the weekend I replaced the heater core on my 2000 V6 Mustang. This was the first time i have does this and it was a challenge to say the least . I had to remove the entire dash, steering column, center console, etc. While doing this I had to disconnect many, many electrical connectors. After replacing the core I put everything back like before. Here is the issue....the power locks no longer work. The driver side window will not go up and down, however the passenger side window works just fine. And finally, the interior dome light no longer works. Anybody have any thoughts? Did I possible miss a connection somewhere when putting it all back together? If so, where might it be located? Any help would be greatly appreciated.

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It sounds like you missed a connection, or broke a wire while taking it apart or putting it back together. Its quite common, especially on such a large job as removing the dash. Since multiple electrical components stopped working, most likely it is a bad ground connection or wire. A lot of electrical components share a ground wire/connection, so if you miss one then multiple things stop working.

However, I'd start with the basics by checking the fuses in the fuse box under the hood, and the one in the left side of the dash. Make sure they are all seated properly and not blown. A visual check isn't enough. Use a multi-meter to do a continuity test on the fuse posts or pick up an inexpensive fuse tester from your local auto parts store. Should take about 5 minutes to test all the fuses.

After that I'd start poking around with a multi-meter to try to narrow down the problem. Sorry i can't give you a silver bullet and tell you which connection to look at. While diagnosing this is much easier if you have the wiring diagram, it can be done without one but it will just take longer.

I'd start at the drivers door window motor. But it helps to know how the motor works. There should be two wires going into it (For description sake, call them Wire-A and Wire-B). To go up, Wire-A will be the power wire and Wire-B will be the ground wire. To go down, Wire-A will be the ground wire and Wire-B will be the power wire. The switch determines which wire will be power & which wire will be ground. So since both directions don't work and to make testing easier, pick a direction (up or down) and only test that direction for the duration of your tests. Otherwise things get even more confusing really quick. For this description, I'll pick Up.

Set your multimeter to as close to 12 volts without going under. Take a small safety pin or needle and back probe one of the wires at the window motor connector. Connect the negative lead to the negative battery post and the positive lead to the safety pin. Then hit the window switch up and see what reading you get. Then back probe the other wire and hit the window switch up. One wire should get close to zero volts and the other should get 12 volts.

If you get 12 volts on both wires, then you have a ground problem. If you get 0 volts on both wires then you have a power problem. Walk up the offending wire till you get a reading you expect. The problem will be between the first point that supplies a reading you expect and the last point that gave a bad reading.

Tip: if your multi-meter leads are not long enough to to reach the battery & the door, you have use a piece of power cord, ethernet cable, normal shielded wire to extend from the battery negative post to your work area.

Good luck...