Trailer wiring

[Timothy2001]

Realizing there are many different reasons the lights do not work on a trailer, are there any most likely causes on the RV side. Trailer has tested to be working fine. It’s a standard Chrysler female receptacle and I k it I am reaching but maybe it’s something simple. Maybe a separate fuse? Flashers and directional don coach work.

[navegator]

Thanks for the up date on the situation, many times we give solutions to pronlems and never get to know if any of ower answers come close to the solution, thank you again.

navegator

[ferndaleflyer]

With trailers its always something. I have 3 trailers, 2 pick up trucks, and 2 motor homes. Every thing works on all of them except when the new DP is plugged up electric brakes don't work on trailer. Will get to it when I have time.

[Timothy2001]

Paring this down for brevity, and here is some context:

Sold house on July 14, buyer needed us out in 14 days, we obliged.
Closing on the 29th, all good, went off without a hitch 🙂
Mistake 1. Without previous testing, connected U-Haul auto transport to coach 30 minutes prior to closing. No power.
Left coach at U-Haul, guys said they would look at it. No luck.
Took to shop I used for my cars, 'wiring guy' came up empty handed.
Contacted mobile RV mechanic, they guy litterally spend six hours looking for elusive power source, mostly under the dash. He gave up. Camping World on Tuesday morning.....no help except they were certain it was a Frieghtliner issue and they were essentially correct.

Through multiple calls from me to Winnebago and Freightliner (who were both awesome I might add) I completly understood the issue. Referred me to a shop 13 miles away, really great folks, spend around an hour and 24 hours after discovering the problem we were on our way with a temporary fix. I still need to access the fuse but now I know where it is.

Now, many of you probably already know this but the trailer wiring on the coach side can be fed from a fuse that coach builders put just about anywhere but it's most likely in one of the rear most compartments. Nobody can tell you and no diagram can show you exactly where, you just need to find it. On this coach, it's behind a panel in the shore power/inverter/ATS compartment......that is insane to get behind. Given enough time, we could have gotten back there but at least we found it. The technician wired in a pig tail to the trailer harness and got us on the road.

Oh and one of the first things the guy at U-Haul checked was the receptacle and its connections and the ground. All were solid.

I do appreciate all the responses. We're sitting in Jennings, Louisiana Walmart at the moment enjoying a cup of coffee and watching the sun get ready to come up. Headed to Fernandina Beach, NC, NY, VT, ME for some lobster and then will land in Jacksonville where we'll figure out where we're going to live.

[Timothy2001]

Gents thanks. We finally got on the road today at 4:30 PM CST and are stopped for the night. The third tech found the elusive fuse but I did not have time to access. We tapped into the light circuit as a temporary fix and got the lights working. This has been a saga and i will update in the AM.

It is not my intent to not answer but time was an issue.

[enblethen]

I asked the OP some questions a while ago but did not receive any answers.

[4x4van]

Timothy2001 wrote:
Everything on the rig works, nothing on the trailer works. No power at all to harness 30 amp breaker/fuse is good. Trying to track down power source now, wiring diagram not proving to be helpful.

Filling us in on exactly what type of rig and what type of trailer you are dealing with would help us help you. Does your trailer have brakes? If so, does your tow vehicle have a brake controller? Do you have a 12v tester or a multi-meter? Do you know how to use one?

I have no idea what "30 amp breaker/fuse" you're referring to, but there won't be a single fuse that feeds all of the trailer lights; so looking for a single fuse or breaker is a waste of time. You need to start at the trailerr plug (on the tow vehicle) and test each terminal for power, then start following those wires toward their source if they don't work.

You are going to need at least 3 or 4 (or 5 if brakes) different wires that need to be hot at particular times; 1-running lights, 2-right turn/brake, 3-left turn/brake, 4-12v hot (for charging), 5-trailer brakes. Additionally, you could have 6-backup lights (rare for a trailer), plus of course 7-ground.

[Executive45]

navegator wrote:
Has any one of you actually cheecked the plugs that connect the trailer to the motorhome, 80% of the time theese connectors fail due to the vibration of the cable, the screws that hold the wires are minuscule and most technicians do not solder the ends, they just jam the wires on and tighten the screw, this also has the added benefit of severing the wires and the end result is a loose wire.

Also take into consideration that theese connectors are open where the cable enters and water does get in, corrotion will take over and you loose connectivity, the other culprit is actually done by the person(s) vigorously either yanking on the plug and cable or moving up and dow and sideways on the connector and spreading the female receptacles in a manner that connections are either intermittent or non existing.

I start at the connector on the trailer and then on the tow vehicle, then the trailer and finally the tow vehicle, I solder the wire terminals and protect both connectors with liquid rubber to prevent any water or moisture from getting in, I have not had an electric failure between the RV and the toad in 17 years.

navegator

Finally, someone who gets it!

OP stated he had power at the TV receptacle and the trailer wiring was ok. That ONLY leaves the connection between the two. Use a meter or 12VDC tester and go from there...Dennis

[navegator]

Has any one of you actually cheecked the plugs that connect the trailer to the motorhome, 80% of the time theese connectors fail due to the vibration of the cable, the screws that hold the wires are minuscule and most technicians do not solder the ends, they just jam the wires on and tighten the screw, this also has the added benefit of severing the wires and the end result is a loose wire.

Also take into consideration that theese connectors are open where the cable enters and water does get in, corrotion will take over and you loose connectivity, the other culprit is actually done by the person(s) vigorously either yanking on the plug and cable or moving up and dow and sideways on the connector and spreading the female receptacles in a manner that connections are either intermittent or non existing.

I start at the connector on the trailer and then on the tow vehicle, then the trailer and finally the tow vehicle, I solder the wire terminals and protect both connectors with liquid rubber to prevent any water or moisture from getting in, I have not had an electric failure between the RV and the toad in 17 years.

navegator

[TechWriter]

Timothy2001 wrote:
Realizing there are many different reasons the lights do not work on a trailer, are there any most likely causes on the RV side.

Been there. I gave up looking for the cause and did an end around: Tekonsha Modulite ZCI . . . Amazon Price.

Since the ZCI works by induction, there's no need to "cut into" an RV's electrical system.

[Timothy2001]

Still unresolved. The tech found a plug under the dash and feels we need a pig tail to connect to the DC distribution panel. I wonder.

I read on another forum that there is another fuse panel unmarked and in another storage compartment that I will hunt for as soon as it gets lighter. The good news is we had a decent view from Wally World this morning.

[JRscooby]

Timothy2001 wrote:
Attempting a second technician............and thank you for the diagram and the helpful comments. Was supposed to be in the road hours ago. Just gotta roll with it!

Unreal.

[Timothy2001]

Attempting a second technician............and thank you for the diagram and the helpful comments. Was supposed to be in the road hours ago. Just gotta roll with it!

[Executive45]

Hopefully this is the diagram you're using.

[Timothy2001]

Everything on the rig works, nothing on the trailer works. No power at all to harness 30 amp breaker/fuse is good. Trying to track down power source now, wiring diagram not proving to be helpful.