truck reverse lights always on when truck camper plugged in

Same plug but different center post wiring. This looks like it could be your problem at a glance.

Converter? Inverter? The systems are DC, so no inverter is required. Sometimes a converter is needed to combine a separate amber turn signal with the brake light to get the proper indication, but most of our US made trucks are not equipped with separate turn indicators. What are you driving?

One trick sometimes used for trailering is to let the hitch coupler provide the negative return path. This is a bad idea in the first place, but is guaranteed not to work with a camper that doesn't connect to the coupler. Weird behaviors result as the current attempts to return through various other lamp filaments.

I just spent hours going around and around on my new camper. In the end, the problems were caused by a set of swapped wires on the truck and a set of mislabeled wires on the camper.

If the 12V from your camper is connected to the backup on your truck, this could happen.

The first thing I would do is get one of these 7-way TEST ADAPTERS from AMAZON-ETRAILER-probably any number of auto parts stores.



This will TEST all of your safety lights DC signals for proper operation. Once all of the SAFETY lights (Running lights-Brake and Turn Signal Lights) are known to be working properly then you can start testing for the BACK-UP LIGHT feature.

Most often the BACK-UP LIGHTS is wired from the center connection and from GND.

Since your truck camper was previously owned it may have prior owner mods to the wiring.. Some truck campers have a second cable installed in the bed of the truck to make it easy to plug into. You may have one these installed.


Got to start somewhere tracing it all out.

ETRAILER has schematic drawings and wire colors for the regular campers - have never looked-up for truck camper diagrams...

Roy Ken

I dont know how your plug is supposed to be wired - we have different plugs on this side of the pond...

But this site might help: http://www.etrailer.com/faq-wiring.aspx

Good point, i'll pick up my voltmeter in the morning and test everything out on the truck, then from the cable to the truck. Thanks. Btw... which connector gives the TC constant power, even when the truck is off? Clearly not the marker lights or they would always be on.

There might also be a ground issue where the power "goes back" through the reverse lights b/c that is where it finds a suitable ground. All sorts of strange things can happen then.

The wiring / connectors could be corroded at either end causing a bad connection even though everything is hooked up correctly. Or you could have caught the plug in something and pulled one or more wires.

Has this very setup worked before?

If you have a multimeter and know how to use it, you could check the individual pins of the connector at the truck side for +12V/ ground and see whether they are hooked up as specified.

So all connectors on the cable are good and propef from one end to the other. Correct me if i'm wrong but... since my TC only has marker lights and the converter "no stop lights or turn signals" i'm throwing a guess that only two connectors are really used. One connector as ground and the other the marker/tail light connector. Am I right? And if so that would mean that somewhere in the TC, the power is going to the power inverter properly but going back to the reverse light connector instead of all the marker lights on the TC. Does that sound possible or likely?

Figured... just wanted to verify with you camper veterans to see if this was some obvious issue with trailers containing power inverters. Never had probs with other trailers, but they were always simple rear lights wiring. Ill check the cable itself to start with.

Assuming your truck is wired right, It sounds like there are some crossed wires. You can look at wiring diagrams, but 7 pin connectors usually make it easy to swap wires with wires secured by screws. With some trial an error, you can straighten the wires out even if your truck has a few things reversed. There are plenty of diagrams available for 7 pin connectors, or if you buy a new one, many come with wiring diagrams.