You indicated the use of a volt meter in your original post. Start with that tool and do some basic checks to find root cause of your electrical problem. Use the meter (Is it digital?), start vehicle, if able, check charging voltage. You should see between 13.2 - 14.8 volts. If not, it's time to do voltage drop test. This test is used while the circuit is on and current is flowing thru the wire. Red led or Black, if your meter is digital, it just show negative, at this point, who cares as it's the same reading. Disable fuel or ignition, have a buddy or remote button, crank the vehicle over with the meter connected on battery positive and other end on B+ at starter. The meter should read 0.50 volts or less. Example; if it reads 2.3 volts, it is corroded inside the cable, cable end or loose. 99% of circuits in a vehicle are in a series. Like cheap X-Mas lights. If one bulb goes out, all of the lights quit. Check the alternator B+ to battery B+, reading should be less than 0.50 volts. High amp circuits have a voltage drop higher than normal like between 0.50 - 1.0 volt. Low current circuits, less than 20 amps, is normal to see 0.050 volts. This is the loss or drop in voltage. The connector, fuse, switch, wires and ground (While on) should total up to 0.90 volts. The components (Horn, Fan, Light, etc.) is designed to consume all of the voltage in the circuit... minus the drop in voltage across all of the other stuff to make it work, like the connector, fuse, switch, wire both positive and ground. Guess what? They total up to battery available. Across the head lamp, DMM reads 12.8 volts, but the battery reads 13.4 volts. 0.6 tenths of a volt is lost across all of the other items. Work quit and does not lye....ever. Retired ASE Master Tech
