Trailer Lights Question

[tim delong]

I have an issue with all the lights on my trailer running lights turn and stop etc. when I have the trailer plugged into 110v outlet all lights work and as soon as I unplug the trailer all lights go out. does anyone have any ideas what the problem might be

[Skip426]

Just so , I have this straight.
When you plug the trailer into 110 power, the running lights and signals come on; when they should not. Am I correct so far?
But when you hook up to your tow vehicle , none of the lights work?

Do you have a battery in the trailer ?
Is the battery hooked up correctly?
Is there any sign of damage to the cord that plugs into the tow vehicle?
Is the trailer new to you, or is this a new problem on a trailer you've had for a while?

[wa8yxm]

Ok The following can be called "RV ELectrical 0.001" (it does not get much more basic.

In the RV is a device called a CONVERTER (See note 1) This box has the job of CONVERTING 120vac to something more closely resembling battery voltage (not 12 but close to it) 13.6 volts DC, normally,

This device both charges the batteries and powers lights, water pump, furnace, and several other systems in the RV, it provides control power for the Fridge, Water heater and possibly the air conditioners and more.

When you pull the plug, Then obviously there is no longer any 120 VAC (Volts Alternating Current) to convert, so the "House" now draws on the batteries.

Possible problems that could cause your symptoms (This is RV Electrical 1.01)

Bad battery.. Bad connection to the battery (often the ground cable) Blown fuse or tripped breaker, Broken wire, Bad wire (I actually had a bad wire) and the big one: SWITCH TURNED OFF.

Most RV's have a disconnect switch, also called a Salesman switch by some, this is USUALLY just inside the door... It may be lit (When you are plugged in) or not. Sometimes it is a simple toggle or rocker switch.. Mine is a 3-position rocker (ON)off(on) (This means spring return to center) that operates a remote device (Solenoid) (Which by the way can fail, in my case the switch itself failed) or it may be a turn key switch, with either an attached knob (Often Red) or a insertable KEY (Likewise often red) there are other options as well.

I would look for such a switch.

Now we come to the power distribution panel, if this panel has both 12 volt fuses and 120 volt breakers behind a common "Last door" odds are the converter mentioned above is part of this assembly.. Also odds are there are some 30 amp fuses.. One of them can be blown

IN any case there is usually a fuse or circuit breaker near the battery, Sometimes it is a self resetting type.. Sometimes a manual PUSH TO RESET type, sometimes it is a fuse.. If a breaker it may have failed.

The procedure: Get yourself a 12 volt automotive test lamp.. Any auto parts store and many auto parts depratments, Trucks stops have em too, This looks like an ice pick with a wire, has a light bulb inside the handle.

Starting at the batteries, Connect the clip to the POSITIVE terminal of the battery and touch the tip to the NEgative Bright good, dark = battery problem.

Now touch the frame Bright = good ground dark bad ground.

Move the clip to the frame and touch the positive Bright (Should still be device is not polarity senistive)

Follow the positive wire till you come to somethign.. This something should have two "Terminals" (Bolts or screws with wires attached) Try both. Bright Bright = good,, Dark = bad wire or connection, bright - Dark Problem found,, Bad device (or triped breaker or blown fuse or open switch)

NOTE 1: Some higher end units have a device called an INVERTER, this does the inverse of a converter (Turns battery power into 120vac) Often the "Converter" in these rigs is part of this device,, I doubt this in your case however.

[the trainguy]

Excellent tutorial!!

[tim delong]

this is a new problem. when I am plugged into the truck I have lights when I unplug the trailer from the house current then the lights go out. also before when I had the unit in storage with out the battery I was able to operate the landing gear and the 12v inside lights from being plugged into the truck now nothing works. I have tested all points on the bumper plug on the truck all is ok. I have replaced the plug on the camper pigtail. I have checked all fuses and breakers on the convertor all are ok

[BigBill3111]

wa8xym...If I read the Original post correctly, the problem is about EXTERIOR RUNNING LIGHTS, not heater, interior lights, stereo, etc.

I am so confused that I almost don't want to reply. I have never seen a trailer that the turn signals, running lights, brake lights, work off of anything except the tow vehicle power source, through the trailer connector, operated by the brake pedal, turn signal switch, and the headlight switch. Therefore, you could tow the trailer with NO onboard trailer battery and NO converter and still have exterior trailer operational lights. The trailer is just that, a flatbed trailer with a livable box on top. If it used to work correctly and now doesn't, I have no idea. The converter does convert 110 to operate the 12 volt interior lights, stereo, etc, but has nothing to do with your tow vehicle. Please let us know what you find.

[Skip426]

Originally Posted by tim delong

this is a new problem.. also before when I had the unit in storage with out the battery I was able to operate the landing gear and the 12v inside lights from being plugged into the truck now nothing works.

This may be the clue to what's going on , using the landing gear with no battery , MAY, have overloaded the charge wire in the RV's attachment cord to the truck and crossed up some wiring by melting the insulation.
It shouldn't have but you're looking at a strange situation so you have to look for a strange cause.
Is there a battery in the trailer now? If you install a battery do the lights come on, same as with 110 power without the truck attached?
Right now , I'm thinking your first step would be to trace the connect cord to the junction box where it attaches to the trailer wiring; this may be under the front of the trailer on inside a compartment at the front; separate the cord from the trailer wiring, ( take pictures for proper re-attachment) and test each wire with an ohm meter, to make sure power going through the cord from the plug , reaches only one wire at the other end.

[tim delong]

I have had the battery in and also out same results. Plugged in all is well. Guesd I dont understand how house current eould matter in tearms of the running lights. I think its a seperate system

[Skip426]

The house current, powers the convertor/charger, that charges the trailer battery with 12v, the trailer connection to the tow vehicle also charges the battery, there is an interconnection there, throughout the trailer there are many areas where the exterior light wiring runs in close proximity to the 12v power from the convertor & trailer battery.

You have to go back to square one; and think back to the last time everything worked correctly. Then try to figure out what could have changed, while the trailer was in storage( corroded connections,on grounds in particular, and rodent damage are real possibilities )

You mentioned replacing the trailer plug; was that done prior to this problem or as an attempt to cure the problem?
Was there a visible problem with the plug that made you consider replacing it?

[wa8yxm]

Re-reading original post

Your tail and running lights should only work when you are connected to the tow vehicle, They have nothign to do at all with 120, completly sepearate from RV electrical system.. These are trailer lights and only connecte to the multi-pin connector up by the hitch that connects to the tow vehicle.

[tim delong]

I replaced the pigtail plug because it appeared to be corroded thought it might help. I am in the process of looking at all the wires and junction box area for any bare wires. cant wait ti find the issue it is driving me crazy.

[BigBill3111]

Did you get this problem handled ?