After Adding Side Marker Lights to Snowmobile Trailer, Some Work and Some Do Not Work

Updated 10/08/2012 | Published 10/07/2012

Question:

i added side marker lights to my trailer 4 lights on each side 3 lights work on one and 2 lights work on the other side, but as i use my tester to check for power my tester lights up but not the bulbs in the lights, bulbs are good. all i did was loop them together 4 on the left and attached to the wire that powers that light and 4 on the right attaching those lights to the wire on the right hand side of the trailer, both seperate wires, if the tester lights up should the bulb?

asked by: Guy

Expert Reply:

Adding the additional lights might be overloading the trailer wiring on the vehicle side. Any given wiring set up is rated for a certain amount of amperage draw. If you try disconnecting the lights that do work and the other ones light up then you know this is probably the problem.

There could also be an insufficient ground at the lights that are not working or at the main trailer connector since there is now more current running through the running light circuit. Since a test light ground independently of the lights and does not draw as much power it probably would light up even if the marker light(s) do not. Try changing the ground locations to somewhere else and make sure they are attached to clean, bare metal surfaces on the trailer frame.

If you switch all of the trailer lights to LEDs it should eliminate the first problems since LEDs draw much less power.

expert reply by: Michael H