The year, make and model info would help.
5 wires
I just changed one. Their are four wires where the wires come into the mirror but only three at the plug that does into the wire harness in the door. THere are two motors with worm gears in the mirror housing. I suspect the wires split 3>4 so each motor has two wires The four wires are a power and a ground wire for each motor. The plug has both grounds combined into one wire.
YES IT HAS A PLUG
The spark plug locations are all on the same side of the engine. They are in the side of the head, where the plug wires are connected.
Yes you can. Remove the door panel. unplug all switches. There are three screws behind the mirror. Two on the bottom, one on the top. The top one is kind of a pain but it can be reached with a small diameter screwdriver. Push the mirror to the top to reach the bottom screws. Push the mirror all the way to the bottom to get to the top one. The plug that plugs into the power mirror switch will have to have the pins removed from the plastic plug. Use a small eyeglass screwdriver to take it apart to get the wires through the tubing. OR you can cut the wires and splice them back to the new mirror after you thread the wires through the rubber conduit (from outside in the mirror housing to the inside of the car). Hope this isn't too confusing.
== == What type of plug are you referring too?
Replace the side mirror on a Mercedes ML 430 by first disconnecting the wiring in the door and unscrewing the old mirror. The next step is to screw the new mirror in place and connect the wires.
To replace the passenger side mirror on a Chrysler Voyager you need to first remove the window trim. Next, disconnect the wires and unscrew the mirror from the door. Reverse directions to replace with new mirror.
You need to remove the door panel. Remove the wires going to the mirror. Remove the nuts holding the side mirror. Reinstall in reverse order.
I'd personally leave it to a professional, but if you insist on doing it yourself, just remove the screws holding it in, remove the electrical wires carefully, then connect wires to new side mirror and install the new one exactly the opposite of how you un-installed the defected side view mirror.
the mirror should just pop out, remove the two heating wires and install the new mirror
pull on the mirror assy. and disconnect the 2 mirror heat wires , to re-install push hard on the center of the mirror to engage the cross swivel , and the 2 treaded . pull on the mirror assy. and disconnect the 2 mirror heat wires , to re-install push hard on the center of the mirror to engage the cross swivel , and the 2 treaded .