Lost tail light power on 7 way trailer plug at moho

[Americanrascal]

2016 Winnebago Adventurer 38 Q. Have driven for years without problem getting power from my 7 way plug to my tow dolly. Today I started up and found no power to my tail lights. Turn and brake lights work perfectly-- only the tail/ running lights. I checked all circuits on the dolly and they were fine.

Then I checked the 7 way outlet on the back of the motorhome and I am not getting power at that point on the tail light/ running light circuit spade. I could see no visible damage or break at the outlet after checking underneath.

I pulled what I think (????) is the fuse in the power distribution box under the hood for that circuit and it looks fine . Tomorrow I will attempt to get the stubborn top of the power distribution box off again and put a multimeter or test light across the fuse connections it to see if I have 12 v running at that point.

I am really at a loss on where to look. This apparently is Winnebago wiring and not Ford as the wires going into the 7 spade plug are numbered as by Winnebago. U am looking at the wiring diagram but not getting very far cyphering it. I am clueless where to search for this one.

[deckape]

Lights on coach ? Follow wire from plug to connection at tail lights .

[Morich]

Agree with Deckape and wonder if coach lights are working?
If they are good, I feel the problem is more like very much closer tot he rear where there appears to be a two pin connector which may be suspect!
Early or late build with 7th digit of 1 or 2 in the serial number? I went with 1 but if not finding the wiring the same on this detail you may need to change to correct that ?
Going tot his drawing for installation to get the physical layout, rather than schematics as they might draw the line:
https://www.winnebago.com/Files/File...ire_184432.pdf

Possible this is the correct drawing and shows a 2 pin plug near the rear that extends wiring to trailer connector? might be able to find that connector and if the other lights on rear are okay, this seems to be a suspect if no damage seen? Some guessing involved and you may need the different drawing for different build if the change happened to involve this but I'm guessing this will match???

See what that might show?
Click snip for best view!


Maybe also need to check ground side?

[be happy]

I am not sure about your set up! On my 07 Meridian in the last outside bin where the power cord etc is a covered panel with the blade type fused for the seven pin connection. As the seven pin was part of the freightliner build and separate from the Winnebago build.

[Americanrascal]

All lights including internal, tail, marker and headlights are working on the coach. Even turn signals and brakes work on the trailer/dolly. Only tail/ marker lights are out on the dolly and no power is present on the brake light spade of the 7 pin feeding the connector to the dolly recepticle on the coach.

Morich, I tore into the drawing last evening and my eye caught that2 pin connector on the schematics. I was under the rig last evening but did not see the 2 pin connector. I'll try to locate again today.

Other than being very dirty around the conduit I saw no physical damage. The drawing is very helpful and gives me some idea where to search. I didn't realize there was a loop around the rear lights that feeds that circuit. Accessing that loop will be fun but maybe checking the 2 pin will be easy if I can find it. I also want to check the ground on the generator thats shown.

Assuming all comes from the loop its interesting that only tail and marker lights are impacted, and not turn and brake lights.

I still feel like I need to go back and check the power distribution box fuse to see if the circuit there has power.

This one is a real head scratcher. Thanks all for dialing in here to help.

[Americanrascal]

I was underneath the rear early this morning searching for loose, broken wires or other anomalies as depicted in Morich's drawings. I could see well up in the rear cap to the tail lights and observed the wires coming from the tail lights (which are working fine on the rig) into the wiring to the 7 spade connector at the rear.

While many of the wires were readily available, accessibility was about impossible as from underneath it is very high up to the connectors coming from the tail lights into the lower hitch circuit on the motorhome.

As everything looked well, my suspect is still something forward on the rig where Ford powers the circuit at the point Winnebago installed the trailer connection circuit. Truthfully though that may be a waste of time as the rear tail lights on the rig are working. Its just that dedicated fuse in the Ford power distribution panel that has me bugged. Other actions I plan are to seek power with a test light along the paths shown in Morich's drawing, and to plug the actual 7 way spade plug connector apart to see if that tail light circuit connection has a fault.

All this is a lot of talk right now as I am parked at a very tight site in an RV park that compounds access to the problem are on the rig.

[Morich]

As I see the drawing the connection to the lights is several different circuits and then connect6ed to the different circuits of the Ford wiring.
The drawing shows the connection tot he Ford wiring being up front with the Winn wiring coming to the rear following the top edge where wall meets side. Then the group drops down the left corner to the left set of lights.
If we think of how the stripped chassis built by Ford and then the RV cabin part built on top, it makes sense. Since Winn is only extending and not adding any more circuits, they are prone to just connecting to the FORD wiring at front and running wires to extend to the back as they build the RV parts.
What that says to me is there is no separate fuse for the taillights in the trailer connection that is different from the taillights on the coach!

Basic idea is that if we get power to the taillights on the coach, we only need to look at why it is not getting on down to the trailer connection!

I don't feel there will be a different fuse for the trailer connection taillights from the normal one for the coach mounted lights.
They almost have to be the same circuit if we turn them both on at the same switch. If they were different feeds, we would have to have two switches, one to turn the lights on for the coach and a second to turn on the trailer lights! One switch turns them both on, so we have to have only one power feed fuse!
If power is good to the left coach light, power is good to that point. Then if it is good to the right, we know the connection that extends across the back is good, also.

But the power is not getting from the left taillight on down to the trailer connection. If we had some work done, etc., a wire might have been cut.
But the most likely thing is corrosion at a connection!
Since they do show there is a plug along the path from left taillight down to the trailer connection, I would have to really look hard for where I'm missing that plug!
Logic says they would leave it out for work and not hidden in the body.
That's trust that may be suspect, though!
But I also know what you mean on not being able to see something like a plug if you have a bunch of wires and maybe covered with some form of cover like a wire loom or a wad of tape!
A bunch of wires, with a bunch of "something" covering them and then throw in a bunch of dirt, road oil, etc. and it may be right there and just look like a funny lump!
It certainly "could" be up where the left light is tied in but when they show there is a connector plug down near the bumper, I'm a hard head to think it is there and hiding somewhere close!

Not much help there but just what I think I would look for! I would have to start at the plug and take off the cover over any lump that might hide a small 2 pin plug! They kind of have a habit of putting some form of plastic tie or straps right at where the two ends plug together. that helps to keep the two plugs from pulling apart as the wires flop up and down.
But it also makes us less likely to spot the plug because we would have to cut the straps to see it under the lump they make! I sometimes find I am against taking things like that apart because I then have to replace or repair it.
But that can also make me miss what I'm looking for!

Beware "saving time" can also be shooting our own foot!
Sorry, setting here at the keyboard is lots easier that crawling around under the RV!

[tderonne]

When you say you checked the what fuses, what ones? The 2016 Owners manual shows an under hood fuse specifically for the trailer running lights: "15 - 20A - Trailer tow park lamps." That fuse is good?

Not that that is how Winnebago wired it, but not sure if you checked that fuse.

[Morich]

Originally Posted by tderonne

When you say you checked the what fuses, what ones? The 2016 Owners manual shows an under hood fuse specifically for the trailer running lights: "15 - 20A - Trailer tow park lamps." That fuse is good?

Not that that is how Winnebago wired it, but not sure if you checked that fuse.

Sounds like good info to know. One thing that is for sure is that every RV is prone to being different!
That means the smaller amount of wiring info we get on the group after 2010 is prone to being different than the early models!
They show us the route of the wires but not where each end is found!

So what does the park light do on a trailer? A different name for backup lights?

[Americanrascal]

Thanks all! This is good info, suggestions and anlysis. Unfortunatly I am going to have to wait until late Monday or early Tuesday when I can get the rig on a slab and I can crawl underneath. Then I'll start intense trouble shooting with a test light and multimeter. I'll post after I find what I can early next week.


I really appreciate all the input and look forward to any aditional ideas and suggestions!
Joe

[Americanrascal]

Originally Posted by Morich

...

So what does the park light do on a trailer? A different name for backup lights?

No power on parking lights either

By the way Morich is spot on, the amount of grit and dirt build up on thew wiring conduits is awsome. But I guess thats expected given all this is behind the duallies on the rear and that area between the rear cap and the coach interior is so open large and such a natural trap for such.

[Americanrascal]

Originally Posted by tderonne

When you say you checked the what fuses, what ones? The 2016 Owners manual shows an under hood fuse specifically for the trailer running lights: "15 - 20A - Trailer tow park lamps." That fuse is good?

Not that that is how Winnebago wired it, but not sure if you checked that fuse.

Tim: Earlier I had managed to get the cover loose enough to get into the Power Distribution panel undert the hood. In my 2016 Ford Manual on page 63-64, it reads fuse number 6 is identified as 20 amp for the "Instrument panel dimmer module. Park Lamp Feeds. Trailer tow running lamp relay coil". Is that the one you are refering to? I pulled the fuse and it looked good. I want to go back with my multimeter and see if I have current coming across it.

Thanks Joe

[Morich]

Okay, brain freeze!
Park lights? Duh, I know what those are, just not right then!
First click on the switch before the rest come on! Thinking too hard on trailer and ignoring the rest!

[tderonne]

Originally Posted by Americanrascal

Tim: Earlier I had managed to get the cover loose enough to get into the Power Distribution panel undert the hood. In my 2016 Ford Manual on page 63-64, it reads fuse number 6 is identified as 20 amp for the "Instrument panel dimmer module. Park Lamp Feeds. Trailer tow running lamp relay coil". Is that the one you are refering to? I pulled the fuse and it looked good. I want to go back with my multimeter and see if I have current coming across it.

Thanks Joe

No.

Fuse 15 "Trailer tow park lamps".

[Americanrascal]

YAY!!! Thank you all for working me through this. I had been looking at the wrong fuse. TDERONNE nailed it and Morich you helped a lot too! Appreciate all who jumped in on this! Pulled that fuse and sure enough it was burned out!

Soon as I pulled the maxi fuse for the Trailer Tow Park lights and replaced it the circuit came back. 12 V and some change on the circuit at the tow connection!

Many thanks again.

(Now I gotta wonder what blew the fuse and sweat that LOL!)

Joe

[Morich]

Ok. Good to hear it is clear!
So many mysteries when I get into talking about the chassis stuff. I totally missed as things are not what I was assuming. probably part of the newer as well as bigger RV with more power needs.
Rather than running larger wires and fuses, they opted to go for an added set of circuits. That may mean they were getting close to too much current draw if they used all the same.

TDRONNE had the right book at the right time! Glad you were able to avoid digging too far into the mess under the bumper!

[Americanrascal]

Originally Posted by Morich

Ok. Good to hear it is clear!
So many mysteries when I get into talking about the chassis stuff. I totally missed as things are not what I was assuming. probably part of the newer as well as bigger RV with more power needs.
Rather than running larger wires and fuses, they opted to go for an added set of circuits. That may mean they were getting close to too much current draw if they used all the same.

TDRONNE had the right book at the right time! Glad you were able to avoid digging too far into the mess under the bumper!

Yea that is what's bugging me a bit. There are only 2 LED tail light light bulbs- less than a year old and rarely used as I don't hardly ever drive after dark--- on that circuit when connected to the dolly. Not much draw for a 20 amp fuse. I am wondering if I am getting some- maybe too much -- moisture in the distribution box that splits delivery to the juice to the 2 lights??? Maybe that's causing a short??? No other visible damage to the lines from the 7 pin connector to the distribution box????????? No other circuits in that box on the dolly are giving me trouble.

[Morich]

What about the running or clearance lights? When the headlights come on, don't they also come on? That might mean quite a lot of drain if all along the top corners, along the lower strip as well as front and back lights?

But that is where we need to get the chassis info that is not handy to get!
I'm afraid that puts it out of where I know more than enough to be dangerous!
I kind of learned to live off my brother's expert advise as he was a FORD guy for years before changing jobs. Then when he retired, he got into building cars from kits and I got to loan some info back to him but very little!
One of those cases where it was always just SO much easier to call him if it was chassis stuff! The way to avoid learning anything is to have an expert nearby!

[Americanrascal]

All exterior lights come on when headlights switched on. But they worked independently of the trailer circuit and were never off. That may indicate they are on the same circuit and the trailer running lights are continuation of the circuit is fused separately? Seems there is an excessive drain on the extension of the circuit to the tow dolly????

[Morich]

Sounds like a different circuit for sure but then it may also only have been a passing item that happened and won't be back!
Maybe something kind of weird about the way the tether plug was pulled out of the connector, so it shorted to blow the fuse?
I don't like to drive around with those mysteries hanging overhead but sometimes we don't get a choice!