weird 12v issue happened...

**Bklabar** · 10-31-2022, 08:04 PM

We were on a 2 week trip with our 260RD 5th wheel, all good until day 12. Woke up to no main cabin, awning, steps and porch lights. They were all working fine the night before. All lights turned off prior to calling it a night. Along with the no lights, on the outside, the left taillight was on, with no connection to the tow vehicle. I disconnected both the A/C power at the post, and disconnected the battery cables. Reconnected both, and still had the taillight Illuminated and no cabin, step, awning, porch lights. Ate breakfast, and then tried the lights again...and bam, all working, and the taillight was no longer on. All was good for 2 days, then the exact same thing....turned the lights out before bed, woke up no cabin, awning,step or porch lights, left taillight was lit up. This time i noticed the Lippert LCD control panel in the pass through was also non-functional. Unhooked from the A/C power, connected to the tow vehicle and left the campground. Stopped for dinner a few hours later, and all was fine? Anyone have anything like this??? Short? Loose wire? loose ground? The single taillight being lit is very confusing to me???? Thanks in advance for any input!

**jkwilson** · 10-31-2022, 08:18 PM

You had something on the 7-pin plug. It was touching something on the pin box or got wet with some contamination on it. That’s really the only way the outside marker and indicator lights can get power on an unconnected trailer.

But losing power inside sounds like your convertor isn’t doing it’s job.

**SolarPoweredRV** · 11-01-2022, 04:40 AM

Originally Posted by Bklabar

We were on a 2 week trip with our 260RD 5th wheel, all good until day 12. Woke up to no main cabin, awning, steps and porch lights. They were all working fine the night before. All lights turned off prior to calling it a night. Along with the no lights, on the outside, the left taillight was on, with no connection to the tow vehicle. I disconnected both the A/C power at the post, and disconnected the battery cables. Reconnected both, and still had the taillight Illuminated and no cabin, step, awning, porch lights. Ate breakfast, and then tried the lights again...and bam, all working, and the taillight was no longer on. All was good for 2 days, then the exact same thing....turned the lights out before bed, woke up no cabin, awning,step or porch lights, left taillight was lit up. This time i noticed the Lippert LCD control panel in the pass through was also non-functional. Unhooked from the A/C power, connected to the tow vehicle and left the campground. Stopped for dinner a few hours later, and all was fine? Anyone have anything like this??? Short? Loose wire? loose ground? The single taillight being lit is very confusing to me???? Thanks in advance for any input!

Your coach has three separate electrical systems; 1) 12v coach that operates everything 12v inside the coach, 2)120 volt system that is only powered up when on shore power (assuming you don't have an Inverter installed) and 3) the brake and running lights which are powered by the tow vehicle.

While these are all separate, there are a few crossover points which tie each system to the other two.

Let's start with your single tail light being on when this weirdness happens...

Since only one tail light is on, it is most likely the left turn signal/brake light and not the "running/tail" light.

In order for this light to be on, it must be getting 12 volts from the battery in some way. The most likely way this light could get 12 volts is through the 7-pin wiring. This could be because the plug itself is shorting out between the 12v charging pin, or there is a short within the 7-pin cable, or there is a short inside of the junction box at the top of the pinbox, otherwise these wires should not be able to cross connect to one another. Note: the reason the 12v charging pin/wire is hot is because it goes directly to the battery for charging from the tow vehicle, once the TV is disconnected, that wire and pin have constant 12 volts being fed from the battery.

Check all your wires from the 7-pin connector all the way back to the battery for chafing, rodent activity and/or loose connections.

As far as your lights go; that is really a mystery, especially in light of the tail light issue.

The next time this happens, disconnect from city water and change your Nautilus to dry camping, then check to see if your water pump is working (yeah, as if the tail light thing wasn't weird enough, now this guy wants me to check the faucets).

The reason I ask you to check the water pump is because GD has a habit of running a single 12v hot wire into the control panel and using that wire to power all the lights (those you mentioned) plus the water pump. So, if your water pump is also not working you have narrowed the problem down to that single wire. When your coach is working normally, find the fuse that controls all those lights and replace it and remember which fuse it was. Then the next time this happens, check out the tail light, if it is on, go inside and remove that fuse, if the tail light goes off (and back on) when you remove and re-insert the fuse this will indicate that this is the wire where the left brake light is getting the 12 volts from. Now all you need to do is find out where these two wires cross one another to find the chaffed wires that are causing all your problems. Repair the wires and separate them to prevent future chaffing.

Good Luck on the hunt and let us know what you find.

**IBEW Sparky** · 11-01-2022, 07:25 AM

Originally Posted by jkwilson

You had something on the 7-pin plug. It was touching something on the pin box or got wet with some contamination on it. That’s really the only way the outside marker and indicator lights can get power on an unconnected trailer.

But losing power inside sounds like your convertor isn’t doing it’s job.

I've noticed most people just shove the 7 pin cord up into the pinbox once they disconnect from their truck. My brother in law had his cord end short out against one of the bolts sticking into the pinbox, and destroyed the end of the cord. I've always had a cap guard similar to this one on any trailer I've owned. Mounted up at the pinbox it allows me to tuck the cord into the pinbox and then plug the cord end into the plastic cap.... keeping everything clean & dry.

https://a.co/d/h5s29oC

**xrated** · 11-01-2022, 08:04 AM

Originally Posted by IBEW Sparky

I've noticed most people just shove the 7 pin cord up into the pinbox once they disconnect from their truck. My brother in law had his cord end short out against one of the bolts sticking into the pinbox, and destroyed the end of the cord. I've always had a cap guard similar to this one on any trailer I've owned. Mounted up at the pinbox it allows me to tuck the cord into the pinbox and then plug the cord end into the plastic cap.... keeping everything clean & dry.

https://a.co/d/h5s29oC

I bought a rubber cap that fits over the end of the cord plug (on purpose a tight fit) and also installed a "Quick Fist" rubber clamp. I just roll the cord up, clamp it in place, up and out of the way and put the rubber cap on the end. Lots of ways to skin the proverbial cat.

**IBEW Sparky** · 11-01-2022, 08:39 AM

Originally Posted by xrated

I bought a rubber cap that fits over the end of the cord plug (on purpose a tight fit) and also installed a "Quick Fist" rubber clamp. I just roll the cord up, clamp it in place, up and out of the way and put the rubber cap on the end. Lots of ways to skin the proverbial cat.

I had the rubber cap type on a previous TT and the problem was that as tight as it fit it still managed to get moisture inside and I ended up with corrosion in the plug itself. Probably human error on my part so I opted for the one I posted.

**Bklabar** · 11-01-2022, 07:42 PM

Thank you all for the information...I will try to re-create it this weekend. My gut is it's something with the 7pin wire into the trailer...to add to the mystery, During travel, every once in a while, i'd get notified on my truck dash that the trailer is disconnected, then it goes right back to trailer connected.