Editing Z31/Relayandfuses php (section)

=== Testing Your Circuit ===

* Voltage Test: Connect one lead of your circuit tester to a known good ground and the other to a connector in the malfunctioning circuit, as close as possible to the battery or nearest fuse. If you are getting voltage here, that part of the circuit is good—continue testing further along. If you find a point with no voltage, the problem lies between there and your last good test point. Some circuits only show voltage when the ignition is in the Accessory or On position.
* Checking for Shorts: Remove the corresponding fuse and connect a test light in its place. Jiggle the wiring harness. If the light comes on, there's a short to ground somewhere—possibly where some insulation is eroded.
* Ground Testing: If a component may not be grounded, disconnect the battery. Use a continuity tester between a known good ground and the wire or ground in question. If the bulb lights, the ground is good. If not, the ground is bad.
* Continuity Test: Disconnect the battery. Connect the tester leads to opposite ends of the circuit. If the bulb lights, electricity is flowing correctly.