September 23rd, 2016, 01:38 PM
Joined: Apr 2014
From: Chilliwack, BC, Canada
I Ride: 2014 FE350, Beautiful Blonde
K just to clarify, You are using a test light to check for a short???? A short is not only a wire grounding but also a wire pinched to another wire. So for instance a high beam wire and low beam wire touching each other would be a short. Anything that is removing the circuit from the length it runs can be a short.
Short to ground
short to power
short to anything in the circuit.
I am thinking the wire to the headlight and tail light are on the same circuit. the circuit is shorting to a high amperage/currant circuit such as the starter and when a load happens it is blowing the lights. I would check the rectifier/regulator circuit as it might be shorting and supplying way to much amperage Thus using the bulbs in a way a fuse would be used, the resistance of the bulbs can not handle the high currant and then it blows the bulbs as it would a fuse.
You need to use a ohm meter and check each wire from one end to the other and then check the headlight or tail light and test other wires to see if you have a short to the other wire. undo every connector you can find and test each circuit, so take the meter and go from one pin on the connector to the pin besides it and so on until you find the short. Disconnect all ground wires as well the battery and see if the ground is shorting to anything as well. The switch might be the issue as high and low might be coming on at once and then back feeding to the tail light.