EMG 81 and 85 pickups make a popular and versatile combination for heavy metal guitarists. The 81 pickup is usually placed in the bridge position, where it produces a crisp distorted tone, and the 85 pickup is placed in the neck position, where it can produce smooth and saturated tones. (You can reverse the positions, however. ) EMG markets this combination as the ZW set because it is endorsed by legendary heavy metal guitarist Zakk Wylde.
Unscrew the guitar's back cover or pick guard so that the electronics are visible. Most guitars' electronics are accessible through the back cover, but Fender and some other manufacturers hide them under the pick guard instead. Once the electronics are visible, take a few digital pictures or draw a diagram of the wiring in case you forget or need to change back to the original pickups later on.
Desolder the old pickup connections where they meet the ground and volume potentiometers using the soldering iron. Unscrew the old pickups and pull them and their wires out through the front of the guitar. Clean all of the connections and set the old pickups aside.
Thread the wires from the front of the guitar through to the electronics compartment and place the EMG 81 and 85 pickups into their appropriate positions, depending on your preference. The letters "EMG" should be pointing upwards towards the bridge.
Consult your photo or diagram and connect the EMG 81 and 85 wires to the appropriate potentiometers. There is an additional red wire that should be connected to the power circuitry containing the 9-volt battery. Do not connect the bridge ground wire, since the pickups are active and therefore do not need it. Depending on the age of the EMG pickups, they may or may not need to be soldered; old EMG pickups need to be soldered, while newer ones feature a solderless design.
Screw in the pickups and replace the guitar strings if they were removed prior to the pickup installation. Since the EMG 81 and 85 pickups are active, they have very little magnetism and should be screwed in such a way as to place them as close as possible to the guitar strings. Plug the guitar into an amplifier and enjoy the new pickups.
Before purchasing active pickups like the EMG 81 and 85, check to see if the guitar has enough space in its electronics compartment to house the 9-volt battery. If it does not, it may be necessary to carve out a slot for it.
If the guitar produces a loud buzzing or humming sound after installation of the new pickups, disconnect it from the amp and remove the 9-volt battery so as to avoid potential damage to the electronics. Check to make sure the wiring was performed correctly and try again, or consult a technician for further advice.