Quote:
Originally Posted by src
my overhead lights have 12 volts when I turn them on they dropped to 8 volts. Changed over to LED bulbs from 4-H. 12 volts at the fuse box when the voltage at the switch drops to 8 volts.
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Do a Voltage Drop test.
You will need your voltmeter and a set of long leads (you can make up a set with some 14ga wire). You put your positive lead on the positive terminal (you can start at battery positive terminal or an interior fuse box if you know the wiring from battery to interior box is good).
Put the negative meter lead on the
furthest light bulb socket or load. With switch turned on you will read the voltage drop. Then start moving your negative test lead closer and closer toward the fuse box (meaning test each bulb-sockets working your way back to the switch). When you find the problem bulb (or wire section) the voltage drop will go to .2V (or lower). Your seeing 4V drop for the whole circuit now as you reported.
You could test in the other direction - from the fuse panel to first switch to first bulb to next bulb, etc. It doesn't matter. The thing you're looking for is where the voltage drop goes from the 4V you're seeing now to the .2V you should be seeing. That is the place where the problem is.
For example if you put your negative lead on the hot side of the light switch and you read 0.2V, that means everything is good up to that pint. Then you put the negative lead on the load side of the switch and you read 4V, that would tell you the problem is in the switch.
Note that circuit has to be powered On to do a Voltage Drop test.
The nice thing about a Voltage Drop test is that you can work your way along the circuit and find the point where the problem is (bad switch, bad wiring, bab socket/bulb, etc.). You just need to know how the circuit is run (what loads are in the circuit).
Linear Mode
