Tracing The Wire

[Bonez69]

2013 Passport Elite 32FB
Tail/Marker lights immediately blow the fuse on my truck.
Turn/Brake lights work.
E-brakes and "+12V" also works.
Truck is verified GOOD with a new fuse and towing another trialer. Also checks GOOD with a 7-way plug tester.

So far, I have verified that the umbilicle cable is not shorting out by a continuity test when disconnected at the trailer junction box.

I did find that the green (tail/marker lights) wire (@ junction box) is shorted to ground with a continutiy test.

So........ Following the green wire from the junction box, it enters the belly area of the trailer. I started to remove the screws that hold up the "corrogated cardboard" type plastic belly cover to further trace the wire. It goes to the driver's side marker light just behind the rear axle. The wires for this light is easily accessible as 2 x green and 2 x white are within the wire loom that come out of the belly. I have identified that one of these green wires is the other end at the junction box. Verified this with a quick continuty test using another long wire to isolate the circuit.

To further verify, I connected only this green wire and the white wires connected; the light works when +12 is applied at the trailer plug (pin3). I am using a resetable fused (20A) jumper to apply the +12V. Fuse rating matches my trucks fuse that get blown.

So where does the 2nd green wire go from here?
I decided to check out the same maker light but on the passenger side since it too is easily accessible via exposed wire loom. Bingo! One of the 2 x green wires on this side appears to be the other end from the driver side light. I now have TWO side marker lights working and now have to trace where this 2nd wire goes.

Here is the "hurdle" happening in following the green wire. EVERYONE of those metal screws (#14x1"+washer) that hold the belly cover on are so bloody rusted that the heads snap off. Not looking forward to drilling these out to reinstall new screws. AND on the passenger side, there is an external propane line (pipe) sandwiching the belly cover. Freaking more dissasembly!?!?

An alternate option (I think) is to stop looking under the belly but to start peeling silicone and removing the light assemblies (one by one) to access the green wire. I am thinking this as there is no other way to trace the green wire to the clearance/marker lights that at the roof line (front and back).

So here I ask.... Has any one "followed the green" wire and can possible reveal ANY quick suggestions from experience? Order of lights to remove?

[flybouy]

There is no answer to your question. If you take 2 of the same models off the assembly floor they may not have the wiring matching. They don't use a wiring loom but rather connect the dots as they best seem fit at the time. I would remove the clearence and tail lights one at a time and inspect for grounding by the positive wire. If you have a to cb energize the lights then with the lights on remove a fixture and pull or shake the wires to see it it shorts. Move/ shake the umbilical cable as well.

[Bonez69]

"connect the dots as they best seem fit at the time".....

Wow, so much for production line standards. LOL

Thanks for the response. I'll post again when I tackle that puzzle again.

Cheers!

[bsmith0404]

Consider the fact that the green wire goes to each of the lights. You don’t necessarily have to access the wire, all you need to access is the light terminals. Pull the covers and the bulbs and see which one shorts to ground.

[flybouy]

Originally Posted by bsmith0404

Consider the fact that the green wire goes to each of the lights. You don’t necessarily have to access the wire, all you need to access is the light terminals. Pull the covers and the bulbs and see which one shorts to ground.

If one light fixture or any section of the green wire is shorted to ground then it will be the same short to ground at all the connections. In order to isolate if it's a light fixture you must disconnect the positive wire from the fixture and check the fixture. If that fixture is clear then reconnect the positive wire and move on to the next fixture. If you check all the fixtures and they are good then the problem is somewhere in between the fixtures and the fuse.

[Bonez69]

"If one light fixture or any section of the green wire is shorted to ground then it will be the same short to ground at all the connections."

flybouy, Glad you said this as I was thinking the same.

Plan at this time is to pull the light fixture to access the green wire connection. Since to fixture are wired in parallel separating the green connection to isolate sections of the circuit. Doing continuity tests with each section should help map the "green wire path" until I find a short (hopefully) just a marette that just fell off.

As mentioned in original post, I have 2 lights operational when +12V is applied to the umbilical Pin#3. Now to guess which fixture to disect next.

[flybouy]

I can't tell you which light will be next but I would assume they use the shortest distance to the next closest fixtur to save wire.

[Bonez69]

All good flybouy, I'm planning to take apart the nearest tail light. It'll be a few days before I have time to try and leave an update. Heading out camping in the AM for a week, daytime driving.

I appreciate the input. Cheers!