I mentioned electrical circuit load testing in another thread, the reason for load testing is that a corroded wire will show power with a normal test light and continuity with a multi meter, but will often drop off or not carry enough wattage under load. This test is for low load circuits, for starting circuits see SheepDog's post below
the test unit is a 7 inch round 3 prong headlight bulb, most 1970 vehicles and some newer heavy trucks other 35/65 watt lights will also work, If the circuit in question is power or ground, simply connect the low beam terminal of the light to the circuit at the suspect end and the ground terminal to the system ground,(power if testing ground circuit) low beam provided s around a 5 amp load, high beam about 10, combined 15 but don't load both for long. Testing wires requires a 12v power source, usually a battery and the procedure is about the same, battery + to one end of circuit, headlight to other end as described above, and a good 14 gage wire to go from the battery - to the headlight - if the circuit is remote. this same tester is handy for finding low load shorts in powered circuits, as long as the load is less than the 10 or 15 amp capacity, if the light shines bright you probably found your short. . the parts store should have a replacement plug for the headlight that you can solder some terminals or gator clamps too to make testing quick and clean cotter pins make good probes for connector blocks etc, and they com in all kinds of sizes
the test unit is a 7 inch round 3 prong headlight bulb, most 1970 vehicles and some newer heavy trucks other 35/65 watt lights will also work, If the circuit in question is power or ground, simply connect the low beam terminal of the light to the circuit at the suspect end and the ground terminal to the system ground,(power if testing ground circuit) low beam provided s around a 5 amp load, high beam about 10, combined 15 but don't load both for long. Testing wires requires a 12v power source, usually a battery and the procedure is about the same, battery + to one end of circuit, headlight to other end as described above, and a good 14 gage wire to go from the battery - to the headlight - if the circuit is remote. this same tester is handy for finding low load shorts in powered circuits, as long as the load is less than the 10 or 15 amp capacity, if the light shines bright you probably found your short. . the parts store should have a replacement plug for the headlight that you can solder some terminals or gator clamps too to make testing quick and clean cotter pins make good probes for connector blocks etc, and they com in all kinds of sizes
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