Trailer Brakes and Interior Lights now don't work

[pfcgrinner]

Have a 76 24' Argosy. Everything worked when I towed it home, but now I have no interior lights or trailer brakes. None of the fuses in the Univolt are blown, nor is the one on the wall near it. Any chance it's something besides a dead inverter? It had been sitting a while when I bought it (at least two years, IIRC)

[uncle_bob]

Hi

First step is to grab a multimeter and see what voltages are where. It's a pretty good bet that the battery is flat after sitting for two years. A very dead battery could simply be pulling the 12V power line down. The Univolt dying is also a good bet ...

Bob

[pfcgrinner]

Sorry, should have clarified this is with no battery in it. Haven't had the battery hooked up at all as the floor was rotted through there. That's now fixed, I have a new battery but haven't hooked it up yet.

[A W Warn]

The power for the brakes come from the tow vehicle. Check to see if the trailer is receiving power from the tow vehicle's brake controller.

The lights are powered from the battery and/or the univolt (converter). The univolt only works when the trailer is plugged into an electrical outlet. Did you check the power source?

if your trailer does in fact have the original univolt, you should consider replacing/upgrading it.

[pfcgrinner]

I fail at giving good info in my original post. Tow Vehicle is a 2013 Suburban with integrated brake controller. Brakes worked fine when I towed it home, but now when I plug the TV in, the controller says to check trailer wiring and they don't work (won't hold vehicle/trailer using just trailer brakes, where they did before).

The interior lights worked for a short time when plugged into shore power but now don't (bulbs are all intact). All outlets still work.

I was assuming the two issues were related since it's all 12VDC power but it sounds like that may not be the issue?

[A W Warn]

Re brakes:
Start with the umbilical cord, check for loose wires in the plug/connectors.
Check beneath the trailer looking for loose wires and connections.
There is no fuse in the trailer for the brakes.

Re lights:
Many old trailers have grounding issues. Look for corroded or loose ground at fixtures, sometimes there is no wire where the fixture contact the metal directly at a screw or rivet. Also check where the univolt is grounded to the frame.
I would install the battery temporarily to see if the lights are working (to check for a bad converter)
Check the power source and the electric panel inside the trailer for a tripped breaker.
There is also a disconnect switch in the trailer. Look at it to see if it is set correctly in use position, not in store position.

[pfcgrinner]

Where's the disconnect switch at? I haven't changed anything deliberately since it all worked but it's possible I hit something while replacing the subfloor up near the wiring block and back near the battery box. Guess it's time to go invest in a multimeter.

[Splitrock]

I had similar experiences. With the brakes, I tested my tow vehicle with a standard 7 way tester. Then I tested the removable umbilical wire. It was not reversible. Next I tested the 7 way socket on the trailer. I found the socket connections wrong. I corrected the socket using a jumper light, a small 12 volt battery charger, and a 7 way tester. Pictures are on my blog.


http://www.airforums.com/forums/blog...1&d=1281379392

[TG Twinkie]

Unless your coach was modified there is no disconnect switch.
There are 2 large fuses, one in the fuse panel and one mounted on the wall of the coach. If either is blown you will lose all 12 volt power
.
You could have a loose ground/common wire: a fuse that is loose in the holder. The converter may be bad.
Install the new battery and see what works and what doesn't.

[xrvr]

Are you saying the brakes don't work when using the breakaway switch? If so, that switch is powered by the trailer battery or converter if plugged in. Do the brakes work when applying the brake pedal?

[A W Warn]

Originally Posted by pfcgrinner

Where's the disconnect switch at? I haven't changed anything deliberately since it all worked but it's possible I hit something while replacing the subfloor up near the wiring block and back near the battery box. Guess it's time to go invest in a multimeter.

My 73 and 78 Airstreams had a disconnect up front near the battery. Looked like this: http://odmrv.com/catalog/index.php?m...oducts_id=1297

I've never owned an Argy. Guess I was wrong about a disconnect in your trailer. Take TG Twincky's advice.

[uncle_bob]

Hi

Grab a multimeter.

1) Check for 120 VAC on the input to the Univolt
2) Check for 12VDC on the output of the Univolt
3) If you have 12VDC on the output, check at a lamp socket.

If yo have no 120 VAC on the Univolt, trace it back towards the shore power. If you have 120V on the input and no 12V on the output, replace the Univolt.

Bob

[USAtraveler]

First check the cable socket on the TV to be sure you are getting 12V at the pin for the brakes (Google "7 pin trailer connector" to identify correct pin). Step hard on the brake pedal and make sure the pin is showing 12V or slightly more. If it's not showing anything, check the underhood fuse for the brake controller. It may be burned out. It's unlikely your integrated brake controller quit working, but if the fuse is OK, you should probably take your TV in to the dealership for troubleshooting.

If OTOH you have 12V at the socket pin, check to look for corroded connections inside the trailer's umbilical cable plug. This is a common place for dirt and/or corrosion to create a bad connection. Spray with terminal cleaner and re-check.

Next, a weak, broken, or corroded wire inside the cable plug could be the source of your trailer brake problem. The outer rubber cover on the cable plug is removeable (slides back on the cable, actually), exposing the individual wire connections. Again, make sure the wires are clean and well secured, especially the ones for the trailer brakes and the ground wire.

If that doesn't get it done, the fix is something I can't imagine. Another member may have a better idea. Good luck!

[Silverflames]

Any time your having 12vlt issues, always check your ground first.