Trailer Wiring Problem

Hello,

I just bought a used 2001 Jayco Qwest 10v pop up camper that has a 6-way square plug for the lights. My vehicle (Rav4) has a 4-way straight plug. I’m having an issue with the lights on the trailer. First off, one weird thing I noticed about the trailer plug is that it’s a 6-way square shape but only has 5 plugs. I’m using an adapter to go from 4-way to the trailer. I’ve confirmed that all of the bulbs work on the trailer but not at the same time… here’s what happens. With the ground wires connected, if I connect the left signal wire and right signal wire to the trailer, both signals work and the brake lights work as well (the brake lights and turn lights are the same bulbs). As soon as I connect the running lights wires together, the running lights come on but the turn signals stop working and the brake lights stop working, but oddly the right brake/turn light stays on as if it were a running light. It doesn’t stay on bright like when the signal or brakes are engaged, it’s just using the dim filament. Any idea why this is happening? I feel like maybe I should take the plug off the trailer and wire up a 4 way straight plug, so there won’t be a need for the adapter from 4-way to 6-way. Maybe that’s where my problem is?

Welcome to In-Depth! Our wiring expert will be here shortly.

Jayco 6-pin RV wiring is a bit different than our typical boat trailers, but here’s what I was able to find;

White on the trailer is ground, just like on the vehicle side.

running lights on the trailer is green, running lights on the vehicle will be the brown wire

Left turn/brake on the trailer is red, which matches with yellow on the vehicle

right turn/brake on the trailer is brown, which matches with green on the vehicle side.

Cutting the 6-pin off, and replacing with a flat-4 is fine, but you’ll have to follow the sequence above.

https://www.etrailer.com/question-16599.html

HRG

Most trailers use the frame of the trailer as “ground”. There is no magic here, “ground” is just another conductor in the circuit. The way this works is that “ground” is used by all the lights in the trailer, it handles all the current. Unfortunately there are a lot of mechanical connections in a trailer, and if they get corroded you will have problems. In your case, I’m guessing there’s a crusty connection that works well enough to let the brake lights work. When you add in the running lights, the extra current is too much and the connection fails.

HRG’s suggestions are right on the mark and a good place to start. In addition, I’d check where the light assemblies bolt onto the trailer. Make sure you have good clean shiny metal to metal contact as the mounting bolts usually are your connection to “ground”. Same thing where the connector is wired up at the front of the trailer. Make sure that “ground” wire is bolted down to the frame of the trailer with a good clean connection.

SR

Very good advise above. Only thing I’m wondering is the 5th wire supposed to be active? If so was it used for Electric brakes or maybe direct power feed to the trailer (so to feed power to 12 volt outlets, maybe charge trailer on board battery)?

Thanks for the replies, everyone! I have followed the wiring sequence you laid out, Hot Runr Guy. The colors were hooked up exactly as you specified, so something else fishy is going on. I imagine the problem is either how the 6 way hooks up to the trailer wiring or the actual wiring to the lights themselves? I’m hoping it’s not the wiring to the lights, it would be a much more time consuming fix. I’ll check to make sure the ground to the frame is looking clean, Steve Root, thanks for the suggestion. IceAsylum, I think the 5th wire that I have is a feed to power the outlets and lights in the trailer, it is red and a heavy gauge. Typically on a 6 way there would be a red wire for power feed and then a blue wire for brakes on the trailer, which I don’t believe this trailer is equipped with. There is an adapter that came with the trailer that hooks up the the 6 way and breaks out to hook up to a battery that I could keep on the trailer if I don’t have power service at a campsite. I’ll try to sniff out the issue soon. I think my best bet is to try to rewire the 6 way plug to a 4 way plug and see if that fixes it.

evancasas wrote:

I think my best bet is to try to rewire the 6 way plug to a 4 way plug and see if that fixes it.

If that does not solve your issue, now is the time to run a dedicated ground (white) wire to each trailer light. By running a white wire from the trailer plug to each trailer light, you will have a much better “ground” than the trailer frame will give you.