Help! No running lights on night before a trip

[John McMillin]

If I've ever needed from you wise old heads, I surely need it now. I'm preparing for a weeklong tour to the Grand Canyon, leaving late tomorrow or early Sunday. Our Scamp hasn't seen road use since fall 2010. Just now I discovered that the running lights are faulty. That's an URGENT problem, and I'm confused.

There are two possible causes:
1) the old (1985) trailer wiring. Our pigtail, at least 10 years old, shows signs of aging. The outer insulation covering the 7-pin wire bundle is separated on one place.

2) the new tow car. This afternoon, my mechanic finished converting a German 12-pin system installed in my Audi to a USA 7-pin. Wrapping it up at closing time, he tested each circuit and pronounced it complete.

So far, it sounds to me like a clear case of a worn-out pigtail, right? But here's the twist. Connected to my old tow car, the trailer's running lights work! None of the others do, but there's a definite difference between the trailer's behavior, between the two cars.

We're willing to try to install a new 7-pin pigtail ourselves. (My wife has a degree in Chemical Engineering, so she's confident!) I'm more hesitant about starting mission-critical projects for the first time, so please school me on pigtail replacement:

-- Where do you cut the old wires and do the junctions?
-- What kind of wire connectors are best?
-- What else am I too inexperienced to be aware to ask?

[xichael]

I was just wrestling with the same problem on an old Boler we recently acquired. It turned out to be corrosion around the bulbs. I took a wire brush to it, and problem solved.

[BCDave]

Originally Posted by John McMillin

If I've ever needed from you wise old heads, I surely need it now. I'm preparing for a weeklong tour to the Grand Canyon, leaving late tomorrow or early Sunday. Our Scamp hasn't seen road use since fall 2010. Just now I discovered that the running lights are faulty. That's an URGENT problem, and I'm confused.

There are two possible causes:
1) the old (1985) trailer wiring. Our pigtail, at least 10 years old, shows signs of aging. The outer insulation covering the 7-pin wire bundle is separated on one place.

2) the new tow car. This afternoon, my mechanic finished converting a German 12-pin system installed in my Audi to a USA 7-pin. Wrapping it up at closing time, he tested each circuit and pronounced it complete.

So far, it sounds to me like a clear case of a worn-out pigtail, right? But here's the twist. Connected to my old tow car, the trailer's running lights work! None of the others do, but there's a definite difference between the trailer's behavior, between the two cars.

We're willing to try to install a new 7-pin pigtail ourselves. (My wife has a degree in Chemical Engineering, so she's confident!) I'm more hesitant about starting mission-critical projects for the first time, so please school me on pigtail replacement:

-- Where do you cut the old wires and do the junctions?
-- What kind of wire connectors are best?
-- What else am I too inexperienced to be aware to ask?

Don't cut the wires. (once cut shorter, its very hard to make them longer again!) Unscrew them from the old connector. Clean and install them to the new connector. The colors for which wire to where should be marked on the inside of the new connector.

After screwing each one into place, follow around and re-tighten. THEN cover each connection with di-electric grease. If it makes you feel better, shrink wrap (heat shrink tubing) can be used as you go along too. The objective is to keep the connections from corroding

The fact that the lights work when plugged into your "old tug' makes me a teeny bit suspicious that the connections are not 100% perfect on your newly-converted new one

[mary and bob]

Try cleaning all the pins or whatever is in the trailer plug that connects to the car plug. I have one vehicle with a 7 pin plug that constantly has a connection problem. I have a set of mini files that I use to clean the plug pins [ actually they are flat connectors in my plug]. An automotive test light is a valuable but cheap and simple to use tool for testing wiring problems, you could maybe test the connection through the trailer plug if you can get at the back side of it, or get the innards out of the housing and plug into the car. Also check to see if there is a ground wire from your trailer plug to the frame, that frame connection could be rusty or bad. A bad ground can cause weird problems, like a feedback through the light circuit. I would check things out with a test light or meter before randomly changing parts. Bob

[Carol H]

Bob's suggest is a good one- had a problem this summer as a result of a bit of rust on the plug but if it works on your old tug my money rides on the new tug not be wired the same as the trailer is. Have had to go back on more than one occasion due to something not working correctly after a new connection was installed on a tug by so called experts. :-))

[John McMillin]

Thanks for that. I'm gong to take the Audi and trailer back to the Audi shop that did the car wiring. They've agreed, bless 'em, to see it tomorrow. I'll have my wife follow me in another car so the lack of signals won't be quite so dangerous. Maybe we'll get out of town on Sunday.

[Frederick L. Simson]

Originally Posted by John McMillin

1) the old (1985) trailer wiring. Our pigtail, at least 10 years old, shows signs of aging. The outer insulation covering the 7-pin wire bundle is separated on one place.

I would replace the trailer's pigtail.
I need to replace mine as the molded plug is separating from the cord insulation revealing the internal wires.


I have a tester for the trailer's pigtail that I made myself. It uses the trailer's battery to power the tail light circuits.
Here is a commercially available unit:

RVupgrades Product Reviews - flashCube

I test the trailer separately with it. If the "flashCube" works, then the trailer is good and the problem is with the tow vehicle's wiring.

[John McMillin]

P.S. -- I doused the pigtail's electrical contacts with alcohol and let that dry a few minutes. Made no difference when I hooked it up...

[Raz]

I have cleaned the contacts with 400 grit sand paper glued to a small piece of wood. While it gets the contacts clean it wears away the plating causing a poorer contact in the end (more frequent corrosion). You can find contact cleaner at any hardware store that is gentler on the contacts. It used to be called TV tuner spray back when TV's had mechanical tuners. I am not a fan of dielectric grease. While it does protect the contacts by definition a dielectric is an insulator. Also it attracts dirt in a very hard to clean place. To test the tow vehicle to trailer ground you can use a jumper cable. I like Freds idea the best, replace the whole thing. Good luck, Raz

[mary and bob]

Carol: Thanks, and you have a good idea in that the Audi shop may have all the circuits working, but they may not be in the correct position in the plug. The plug that Frederick shows is what I have on two of my 4 tow vehicles, and for some reason I always have contact problems with one of the vehicle plugs. The contacts are brass and just get dirty or corroded. Most of my trailers have the 4 pin connectors so I have an adapter to go from the 7 pin to 4 pin plugs. It'll be interesting to see what the solution is to John's problem. Bob

[Bill in Pittsburgh]

Once you have solved your problems, do not forget to apply dielectric grease to all connections where corrosion can be an issue. Use it liberally to your tug to trailer connectors when trailer is not in use.

[Carol H]

Bob I have the same adapter as well and your right corroded parts can do it - my tug stopped charging the battery on the trailer this summer while I was boon docking for 2 to 3 days at a time and then hitting the road for 8 hours or more - was counting on the tug to top off the battery while driving. All the trailers lights worked fine though. I have a small solar panel that just kept me going until I could get an RV shop to fix the issue - late July so those I stopped at along the way had a one week or more waiting period. Took several days to find a place that would fix it or even put a tester on it for me to see what the problem was so I could buy the parts to fix myself. Gurrr Problem turned out to be corrosion on the tug plug - I ski a lot so the tug is subject to salted roads in the winter. The bad news is like John the RV shop that replaced the plug was in a hurry to go home and claimed it was all good and backed the tug out of their yard and locked the gate and went home. When I re connected the trailer which was parked out on the street the bad news was that although the battery was now being charged the turn signals didnt work...played with the plug a bit and the turn signals worked but then I had no night running lights ... ended up having to change my travel plans for that evening and stay were I was in order to get it sorted out in the morning. Turned out the problem was that the new plug they put on the tug did not fit as snug to the trailer plug as the old one did and if not wiggled correctly certain light functions would not work.

[John McMillin]

Alrighty, I'm pleased to report that all is well. All the trailers's electrical functions are back up to snuff, my mechanic tells me. He had the trailer for over two hours. He removed some internal corrosion from the pigtail plug's contacts, using small files, and replace da broken wire. Would it have been better to spend minutes replacing the whole pigtail? Probably, but given the awkward timing of this unexpected problem, I'm grateful to see it wrapped up and done, by any manner. My mechanic is merciful- he only charged one hour, at $105.

Though I might have done the job for less, it might have failed, and surely it would have eaten into valuable packing time. Since last night, my vacation clock is ticking!

We plan to get up early tomorrow and drive to the Moab area, halfway to the South Rim. Hopefully, some of the Colorado River campsites above Moab will have cleared out for Sunday night. That's a hidden bonus of this lighting emergency. The next accounts of this adventure will be in the Towing or Trip reports areas. 'Bye now!

[Raz]

Great news. The BLM sites are great. Safe travels. Raz

[mary and bob]

Carol: My adapter is one I made, and here in the northeast we get plenty of corrosion problems. When I worked on trucks, lighting problems were an everyday task. John, glad it's fixed, have a good trip. I'd like to get $105 for an hours work !!! I'll have to charge myself about $400 for the rewiring I just did on our Uhaul. Bob

[Frederick L. Simson]

Originally Posted by mary and bob

I'd like to get $105 for an hours work !!!

If John's mechanic is one employee of several in a business, then so would he.

My employer charges $132.00 per hour for my work. I only see a fraction of that.