The pickup is the heart and soul of an electric guitar. Without it, no one will hear those great sounds you are playing. The main types of guitar pickup are single coils, famously used on Fender guitars, and humbuckers. Although different, they adhere to the same principles and are checked in the same manner. Although, pickup problems are usually a result of faulty wiring and soldering, guitar pickup coils can eventually break down. When checking guitar pickups that are possibly faulty, a multimeter is needed.
Access the pickup to be tested. This requires removing the guitar strings and, on some models, removing the pick guard as well. All of the hardware is removable with a small Phillips-head screwdriver. Remove the screws surrounding the pickup and remove any covers. The inner-workings of the pickup and the two lead wires are in view.
Locate the two pickup leads. Two wires are attached to the pickup, leading to electronics such as volume and tone knobs. One lead is negative and one is positive --- normally coded by a black negative wire and a red or yellow positive wire.
Prepare the pickup leads to be tested. To test the leads using a multimeter, the probes need to contact bare wire. If bare wire is present at the end of the leads, this is no problem. If not, the wire needs to be exposed. Cut a slit into each wire, using a razor or small knife; cut just enough to insert the probes into each wire.
Test the leads using the multimeter. If using a digital multimeter, set the range on the multimeter to 20k ohms. If using an analogue meter, obtain a zero reading by placing the two probes together and turn the Zero Ohm Adjust until the meter reads zero.
Measure the pickup's resistance. Place the black probe to the negative lead and the red probe to the positive lead. When a resistance reading is obtained on the meter, the pickup is functioning, the higher the reading, the better. If no reading is given, the pickups are probably faulty. Single pickups should give a reading near 10 ohms and humbucking pickups should read closer to 20 ohms.
Reassemble the guitar by covering the lead wires with electrical tape where the slit was made. Replace any covers and refasten the pickups to the guitar.
When preparing the lead wires for testing, make sure the guitar is not plugged into an amplifier. Be sure to leave the wires intact --- do not cut across the wires.