7-Pin Harness

[silverloaf]

I replaced the 7-pin wiring harness on our '88 30P early in our restoration work. It worked fine but I didn't take the length of WDH into account. I tried using a jumper harness but it blew the trailer's marker light fuse in my truck on the 1st hook-up.

I purchased a longer harness and will install it this week. But I want to verify the path the new harness should run near the hitch receiver. This includes the proper amount of slack when hooked to my truck.

Can anyone help me here? A pic would be great but a good description is also welcome.

Thanks in advance for your help!

[KYAvion]

Something I did is I installed a junction box for connecting the 7 way cord and plug. This way, replacement of the cord that leads to the 7 way is easy. It also allows me to easily troubleshoot issues if needed. As far as length, I’ll try to remember to get a pic when I’m at my trailer. I have extra length though, which I wrap around the tongue jack loosely. This provides me with a little slack that can be taken up by movement along the hitch if needed.

[silverloaf]

Thanks KY.

[silverloaf]

Before installing the new 7-pin harness, I decided to connect the existing harness to the truck first. It blew the dedicated running light fuse in my truck. That means the jumper harness is not the problem. Thus, I must have a short in the running light circuit somewhere in the trailer. Perhaps I spiked the wire with a screw.

Does anyone know the path the running, turn and brake light wires are routed through the body on an '88 30P? Once I know the general routing, I can back-track to see where I might have spiked the wire. I'm certain the routing is common for most trailers in that era

Thanks in advance!

[KYAvion]

I don’t know the exact route of the wire runs, but when that fuse blows do only the running lights stop working? Does everything else work fine?

[KYAvion]

Measured straight out from the front of my hitch my umbilical extends 18”. If measured straight out from the tip of the coupler it’s at 28”. Of course it would extend further if it wasn’t wrapped around the tongue jack, but I just leave it wrapped around to take up some of the slack and also to keep the cord elevated a little. I could have cut it shorter instead of having it wrap around, but it works well that way and leaves me with a little cushion. Attached is a pic showing the junction box.

[silverloaf]

I don’t know the exact route of the wire runs, but when that fuse blows do only the running lights stop working? Does everything else work fine?

Thanks for the info. Yes, the other lights work.

When I installed a new 7-pin harness in 2017, I took a picture of the connections at the distribution pocket under the front of the trailer. Green wires denote running lights. There are 3 wires connected to the one out of the harness. I'll need to separate the wires and conduct a resistance test of each branch. I feel grateful because chasing a one wire from front to back could be a real pain.

By the way, the dedicated trailer running light fuse in my truck is 25 amp. That's pretty serious current draw into the trailer to blow the fuse.

[Razorback]

I finally found a picture that I knew I had somewhere......

[silverloaf]

Thanks for the pic. Your harness run high over the A-frame, not low as I had routed my replacement.

[Razorback]

That seems to work well, and the pigtail is long enough to drape over the propane tank hold-down bracket. Speaking of that, I like to put the connector inside a quart-size ziploc bag and seal it with a Velcro strap when not in use....also use dielectric grease on the connectors.)