Running Lights Trouble

[TexasDad]

Suggestions for trouble shooting running lights. Currently the 2 front right and left (amber) running lights work. None of the (red) rear running lights come on. I have pulled the lights and confirmed that they are not blown. Checked for power at the light socket, none.
Shouldn't these lights be connected together, or is there a possible fuse to just the red running lights?

The Brake lights are functioning fine.

[TexasDad]

More details about 5th wheel.
2011 ForestRiver Wildcat 30QBT

Thanks for all the troubleshooting tips.

[JRscooby]

Lynnmor wrote:
Still talking about testers when the two working lights tested everything to that point?

Not sure I agree 100%. I have seen trailers where a few lights ground by back-feeding thru the brake light circuit.

enblethen wrote:
What type of skin is on the rig, metal or fiberglass? many metal skinned rigs uses the skin as ground.

Yes, in times past this has been tried. If the trailer is doing it now, the best idea is pull in a ground wire.

[enblethen]

What type of skin is on the rig, metal or fiberglass? many metal skinned rigs uses the skin as ground.

[Lynnmor]

Still talking about testers when the two working lights tested everything to that point?

[JRscooby]

enblethen wrote:
This style for testing a standard seven way receptacle.7 way tester
Please clarify what is working. Do the taillights work? Does any of the small clearance lights work?

This style of "tester" can lead to a lot of wasted time. Yes, if you plug it in, and get no light out of the LEDs, you have a problem with the TV. But what happens way to often is you plug it in, all LEDs light as they should. So you "know" something is wrong with the trailer. Spend hours chasing ghosts around, take apart things, open no telling how many places to cause problems later. Finally you give up, call somebody that knows what they are doing. One stand of wire making contact will carry enough power to light that little LED right at the end of that short wire. Put the load of the longer wire, and many larger lights (even LED) and it will not carry. "Testers" like that are made to sell not to use.
I have worked on many light systems, mostly for guys that had to move, and had to have working lights to move. 1 light out? Start at light. More than 1? Start with ground.

[DFord]

TexasDad, just what are we dealing with here - a trailer/5th wheel or a motorhome? Running lights/marker lights to be more understandable to most folks.

I like the idea of checking the grounds at each bulb. The marker lights should share the same circuit with the tail lights.

[enblethen]

This style for testing a standard seven way receptacle.7 way tester
Please clarify what is working. Do the taillights work? Does any of the small clearance lights work?

[JRscooby]

gbopp wrote:

agesilaus wrote:
Get one of these and see if your truck is the problem.

Which item are you suggesting? Your link goes to a page of items on Amazon.

Does not matter which. Once you give the card number they all have done what they are designed to do; Take money out of your pocket.

[Old_timer_Dave]

A stupid idea but from the description the trailer sounds to have a central line and branches off to one or both sides. as to where the central line is located who knows but the manufacturer. It maybe a faulty bullet connector in line on the main positive.

[Mike_S_620]

It sounds like you have a loose wire. A fuse would cause all the lights to turn off. I assume that you are talking about a trailer. If so, then having the front lights on shows that the TV plug is working. It is not likely to be the ground that is loose because the brake lights usually use the same ground as the running lights, if it was a ground then the brake lights would not work. It has to be the + wire that is bad. Most trailer lights are daisy chained, have wires that go from one light to the next to the next etc. When a wire gets lose everything after the loose spot turns off. In my trailer the chain starts at the front right, across the front to the left, down the left side, then across the back to the right side. If you follow that pattern I would remove the first light that is out from the trailer to get at the wires behind it. Look to see if there is a bad connection, and check the voltage at the wires. If everything looks good I would check the last light in the chain that is still on. If connections are tight at both lights, then probably a mouse has chewed the wires between.

[Gdetrailer]

Amber AND red "running" or marker lights are all on the same circuit and IF there is a fuse on the trailer (most do not have a fuse) it would have to be good in order for the front makers to light up..

Rules out the vehicle AND a fuse on the trailer if the front ambers are working.

You have either a broken ground or broken marker light wire going back to the rear of your trailer.

Since the Stop/Turn lights are working that pretty much rules out a broken ground since the Stop/Turn lights share the ground wire used for the rear markers.

Pull the drivers side rear taillight and verify if you have power on the taillight marker.

No power there most likely a break from the front to back.

You can follow the TV to trailer cord on the tongue, back to the junction box on the trailer. In that junction box if you are lucky the manufacturer may have run the rear marker light wire to that box. Verify that all wires are connected properly.

You could run a temporary marker light wire from the front junction box of the trailer to the drivers rear tail marker and see if you get results (this effectively bypasses the wiring in between front and rear).

If the temporary bypass works then just find a permanent route to run the replacement wire along the underside of the RV.

Marker light wiring tends to be point to point (from marker to marker) making finding bad wiring a real joy sometimes..

[Lynnmor]

If any of the running lights have power, you already tested the truck, no need for a tester. You need to find where the disconnect is, perhaps there is a common ground for the remaining lights.

Run a temporary ground wire from the frame to one of the failed lamps and see if it lights with the ones that work.

[MitchF150]

Check the ground wire(s) for the red running lights.. If you have power to the fronts, then you are getting power to that at the plug.

[gbopp]

agesilaus wrote:
Get one of these and see if your truck is the problem.

Which item are you suggesting? Your link goes to a page of items on Amazon.