No Explosion

[anthonbloom]

I arrived home from a weekend camping trip in my 2012 Cougar 318SAB and parked in my driveway, plugged in to 30 amps and had a good night's sleep. The next morning I notice the front amber marker lights were on and puzzled as to how that could be. I reconnected the trailer plug to see if that made a difference...it didn't and discovered that none of the rear lights, indicators or brake lights were working. I disconnected again and looked up under the hitch at the electrical connection box and gave the looms a wiggle and the lights went out but there was a burning smell. I shut off the battery disconnect and unplugged from the shore power and shone a flashlight in there. The wiring loom was fried coming out of the connection box, the green wire ( ground? ) had lost all its insulation and most of the copper had vaporised and the red wire ( positive to battery? ) was melted into the rest of the wires. When I looked at the other end where it passes from the frame member and through the propane compartment, the wires were also fried and still fizzing and melting. After disconnecting the battery I saw that the wire from the positive battery terminal was fried and that the whole loom was ruined. I used a camera probe an looked inside the chassis member and the insulation was burned off on there too.
So, I tried tugging on the loom to see if I could cut it and pull it through with a replacement cable attached and it's barely moving. It may be strapped somewhere or restricted by connections to marker lights. I tried pushing a piece of stiff cable with a loop around the loom but it won't go all the way. I will try again with a fish tape. I am also exploring to see if I can route a new cable under the plastic covering into the front compartment but the whole area under the front is covered and it looks like a major job to get that down enough to access the loom and then I have to put it back again....
No fuses blown, battery disconnect doesn't disconnect the battery and somehow a burning cable 3 inches from the propane connection didn't cause a fire or explosion. It must be my lucky day. I will gather my resources and see if I can effect a working repair.

[Tbos]

Wow, I wish you the best as you repair it. If you find out what caused it let us know.

[anthonbloom]

Plan A was to splice good wire into the loom where the insulation had burned through, but there was too much damage and the worst offender, a #10 wire to the positive battery circuit breaker, had melted everything it touched inside the frame rail, where I couldn't reach it. I think it welded the whole loom in place as i couldn't get anything to move by pulling on it. So, Plan B and day 2, I traced the wiring back from inside the front compartment where it went back to power the lights and trailer brakes and drew myself a diagram with coloured pencils so I knew where everything went and what colour connected to what. Some of the wires for the marker lights went in single and came out double, so that took a bit of figuring out. Long story short, I made up a new loom out of the correct size wires and ran it straight back from the pin box under the outer cover into the front compartment, routed it along the top of the front wall, round the landing gear and into a box with seven screw posts which I attached to the back wall next the the existing connection panel. All the wires were terminated with crimped automotive rings and joined to the correct wires that I cut from the original loom. Once completed, I reconnected the battery, but nothing worked. A little bit of jiggling caused a click to come from the main panel, and I found that the accessory post on the 30 amp circuit protector was loose and making intermittent contact. I removed it ...shortstop it said on the side...and it was burned through on the back. I replaced that with a new one and everything works again, and .... no smoke.
The most difficult part of the job was figuring out the circuit plan, despite much searching the best diagram I could find was from a 1968 Mercury Cougar....not a lot of help!

[MarkS]

I am glad you got your trailer back together without an explosion. The lack of schematics from keystone is really annoying.

People should be aware that the factory disconnect does NOT disconnect all 12v devices. I believe that the propane detector and the brake away switch are powered when the disconnect is open (off). I think that is a real problem when you have an electrical issue. There can be a surprise hot wire. It also draws down the batteries while the trailer is in storage. I added my own disconnect at the batteries.

When you need to work on the 12v Systems, it is best to disconnect the batteries, unplug shore power and generator, and unplug the Tow Vehicle.

[ctbruce]

Or install a second battery disconnect switch ar the negative post. That waybEVERYTHING is off. And no Boom!