Clearance lights always on

[Docfranco]

Hi
I’m a relatively new owner of a 73 31” AS.
I began to bring it back to life and am perplexed at how the clearance lights seem to have an unknown and separate power source.
I began by wiring in a new plug to hook to truck and all was good, lights worked etc. then I added a battery as it came without one. Then all the clearance lights came on and the brake /tail lights. I then pull all fuses out of the Univolt and still have clearance lights on. Then I cut all the wires to the plug thinking it may be backfeeding into the lights.
Still have clearance lights on.
I appear to clearly see where the battery cables come to the univolt and there seems to nothing else tapped into the battery to power the lights.
I am stumped...

[HiJoeSilver]

Do you have a manual. Mine is 300 miles away, unfortunately. There is a separate fuse panel for the tow circuits. Usually located on the front bulkhead somewhere. That still doesn't explain what is giving positive power to those lights. Did you still have your tow vehicle connected. Sounds like you installed a new 7 pin connector, the old 74 wiring doesn't match current standards. If your TV was still plugged into the trailer the mismatch in old and new wiring could be the cause.

[TG Twinkie]

Pull the fuse labelled "car battery" and see if the lights go out.
Then pull the fuse labelled "trailer battery"
Reinstall the "car battery" fuse. If the lights remain out.
It sounds like you do not have the 7 pin plug wired to todays standards.

[Docfranco]

Where are these fuses?
I’ve pulled all fuses in the univolt...

[Docfranco]

AND cut all wires at the trailer plug in

[TG Twinkie]

They are in the Univolt. The two large fuses in the lower left corner.
They are clearly labeled in your pic.
Don't cut the wires. Disconnect them.
If it is a molded plug go to the other end of the Umbilical cord.
Tell us what color the 7 wires are.
Typically they are as follows.
Black=+12volt=Charge line=car battery
White=Common/ground
Red=Left turn/brake light
Brown=Right turn/brake light
Green=Tail/marker lights
Blue=Electric Brakes

[HiJoeSilver]

Originally Posted by Docfranco

AND cut all wires at the trailer plug in

So are there loose wires at the trailer plug end? Your battery is still connected from the description. One of the wires in the trailer umbilical is connected to the battery for charging from the tow vehicle. If so you probably have some voltage going from that wire to the other light wires.

[OTRA15]

Originally Posted by Docfranco

Where are these fuses?
I’ve pulled all fuses in the univolt...

If you don't have an owner's manual, we can probably locate one online.

Please advise, and good luck!

Peter

[overlander63]

1973 had different wiring colors and locations from modern trailers.
In 1973, I think the blue wire was battery charge, instead of trailer brakes. There are many resources showing older standard wiring and newer standard wiring. Use the ewer standard wiring umbilical diagram to wire the plug correctly, using the old wiring diagram to know what color wires went where.

[TheGreatleys]

Hang on. You swapped the umbilical plug, then after you added the battery, your running lights stay on? Check your wiring on your umbilical plug for a short. Specifically between the fat blue wire (aux + or battery charge) and the green wire (running lights). Those wires connect super close together, and it's real easy to let them touch. You may want to add some heat shrink insulation or electrical tape to make sure they can't touch.

When I redid my umbilical plug, I had an intermittent short between the left turn signal and the trailer brakes. Same problem. Ask me how fun that was on the highway.

[Ralph12]

Does your TV have "Daytime running lights" if your trailer is hooked up to it they will be on as well, disconnect from TV and see if they go out.

[Wazbro]

Some people added a switch to have their running lights on for decoration (and to make it easier to find their trailer) while parked and not connected to the TV.

[HiJoeSilver]

Originally Posted by Wazbro

Some people added a switch to have their running lights on for decoration (and to make it easier to find their trailer) while parked and not connected to the TV.

Possible, but people don't usually do the brake lights as well. If they did thecswitch is likely near the tow wire fuses which are usually on the front bulkhead or along the street side wall somewhere.

[TheGreatleys]

Originally Posted by HiJoeSilver

Possible, but people don't usually do the brake lights as well. If they did thecswitch is likely near the tow wire fuses which are usually on the front bulkhead or along the street side wall somewhere.

The running light circuit powers the tail lights, too, i.e. the brake lights. Same wire.

[TG Twinkie]

Running lights and brake/turn lights are on 3 different circuits.
1 Running lights
2 left turn
3 right turn

[TheGreatleys]

Originally Posted by TG Twinkie

Running lights and brake/turn lights are on 3 different circuits.
1 Running lights
2 left turn
3 right turn

Right, but same lense, same bulb, different filaments. It seems likely that OP has a short to the running light circuit which is illuminating the tail lights, i.e. the brake lights. Less likely there would be a short to three separate circuits.

[Docfranco]

Originally Posted by TheGreatleys

Hang on. You swapped the umbilical plug, then after you added the battery, your running lights stay on? Check your wiring on your umbilical plug for a short. Specifically between the fat blue wire (aux + or battery charge) and the green wire (running lights). Those wires connect super close together, and it's real easy to let them touch. You may want to add some heat shrink insulation or electrical tape to make sure they can't touch.

When I redid my umbilical plug, I had an intermittent short between the left turn signal and the trailer brakes. Same problem. Ask me how fun that was on the highway.

This was where I found a problem, when I wiggled the plug that goes into the front of trailer the lights flickered ... when I removed it they went off.
I will get a new plug for front of trailer.
Thank you for the pointers.