Messed up adding extra LED tail Lights

[Flyn2high]

I Added extra tail lights to my 5th wheel but really messed up.

We travel with a pair of e-bikes on the back of our 5th wheel. The cover somewhat blocks the tail lights and I really wanted to add extra tail lights above the bikes. When After reading a lot of posts on additional tail lights I thought I could do an easy mod just a little differently.

What I know now after my big fail is how Grand Design routs the running light cable in our 310GK Solitude. It is a two wire 16 awg white and yellow striped cable similar to a lamp cord. The white lead is ground and the yellow striped one is positive side of the running lights. The cable connects to front amber lights first and then runs in the belly along the left side. It breaks out in the left rear and is accessible under the bottom left corner of the trailer. Then it goes up into the far left corner. There is an aluminum square frame member that goes from top to bottom on the left and right sides of the trailer. The cable runs inside this channel up to the top and then feeds the three red marker lights on the top rear. Then it come down the right side channel and connects to the right rear side marker and then to the right trail light. Then to the left tail light and finally to the left rear side marker. The left and right turn signal have separate wires. Red on left and I think green on the right.

I wish I knew this before I started because I made a hole in the cable inside of the aluminum channel.

I did not want to splice into the wires at the bottom because they were exposed to weather and making a three way splice would be difficult to water proof. What I did was to tap into the tail lights directly, then run my cable out to the side. Then run it up in the corner angle inside vinyl cover. Then over 5“ from the edge to my new rear tail light.

I did the right side first and removed the screws from the corner angle almost to the top. This way I could spring the angle away and make a cable hole from the side directly to the tail light. I used an 8" long 1/4 drill bit. It went through the outer wood and laminate, then through the aluminum channel (at the time I did not know the running light cable was inside this channel) and through the Styrofoam to the tail light. This hole would be covered when the angle is put back. I then drilled a 3/8" hole from the rear though the angle to intersect the first hole to be able to run my wires through. The smart thing I did after every light was connected was to test the running and turn signal lights. At the end when the left new LED tail light was all connected I tested one last time. But now only the turn signal lights worked. None of the rear running lights would come on including the top rear and bottom rear side marker lights. Only the front amber running lights worked. I could not imagine what went wrong. The last thing I did was to drill the cable hole for the new left LED light.

Based on the pattern of lights that were out and many hours I figured out the cable run and how my last drilled hole must have cut the running light wire buried in the wall. I confirmed that by looking in the side hole with a bore scope. I could see the frayed wire. I measured it to be 2" from the outside edge. At this point I assumed it to be along side the channel. I opened up the wall using a razor saw only to discover that it was actually in the aluminum channel.

I could see the cable at the very bottom going into the channel and it must rout to the left rear top marker light. On my trailer there is a cabinet that runs from left to right above the sofa. I cut a second access hole inside the cabinet in the ceiling at the left rear corner and found the endo of the cable. I bought a new 16 awg white lamp cord cable from Lowes cable and used the old cable to pull the new one down through the channel and out the bottom. Then I made a nice solder splice and enclosed it in heat-shrink tubing. Now it all works.

Any method of using the corner angle’s vinyl strip and drilling into the rear wall to hide the cable runs the risk of damaging the running light wire as I did.

I actually tried drilling a wire channel up from the tail light by using a flexible plastic tube in my drill. It cut through the Styrofoam nicely but I hit a hard stop half way up. There must be a cross member inside the wall.

I think it I were to do it again I would play it safe by drilling a hole behind the old tail light clear through the wall. Then run the cable up on the inside and out through a second hole where the new light will be. I actually measured the current in the LED light on the bright setting and it was less then one half an amp (390 ma). I used a three conductor 22 awg cable which is the correct size for that length cable and current. The cable is very small and you could hide it with a thin piece of molding that is slightly carved out in the back side.