Forum Discussion

Mickeyfan0805's avatar
Apr 22, 2016

New Wiring Harness - need help!

My wife backed into an especially hard snow bank over the winter and the result is that the 7-pin wiring harness needs to be replaced. But, I am having problems.

I'm having a number of issues, but the first and foremost is that I can't seem to get the circuit tester to work properly. I have an automotive circuit tester. I am connecting the alligator clip to various points (the hitch, the frame under the truck, etc...) in order to ground it, and then using the tester on the leads of the harness - I get no signal on any of them. When connected to the trailer the lights are working properly, so I know there is power and function, but I am doing something wrong with the tester.

I want to make sure this circuit tester is working properly before I cut the wires and start marking functionality in order to wire the new harness. If anyone has any sense of what I am doing wrong, I would greatly appreciate the insight.

Thanks!

5 Replies

  • RoyB's avatar
    RoyB
    Explorer III
    AH so I misread... sorry bout that chief...

    Roy Ken
  • Thanks RoyB - but I am replacing the harness on the truck. The plug for the trailer is in great shape.

    I've been thinking it was likely the ground. I've sanded it down pretty well, but maybe I need to go further. I'll give it a shot.
  • I believe he's talking about the truck end? Are you using a multi-meter to test your wires? Change the battery on the meter and try it on something like a battery in your truck or just a AA battery or something similar. Then you will know if your meter is working.
  • Go to your battery and use the post to test the tester. If it functions ok you need to find a better ground at the hitch. Grind some place shiny clean and connect to that. I actually screwed a crimp connector for a wire on a place made shiny and clean. I can alligator clip to it with confidence. If you have a piece of wire long enough just run it to the negative battery post.
  • RoyB's avatar
    RoyB
    Explorer III
    If no has done the cut and paste before your 7-way cable should be a breeze... Most of them terminate into a weather tight electrical junction box just inside your trailer frame... If all is normal all you do is replace color for color. Some are tied together with large yellow twist connectors... Other have lugs and are connected to a terminal strip... Unless someone has made changes already it is as simple of remove a BLUE WIRE for instannce and repacing with the new Blue wire etx...

    ETRAILER.com has a nice video showing their 7-way cable being hooked up...

    I would replace the whole cable and not cut into it and add a length...


    ETRAILER has your exact 7-way cable with molded connector and it used to come in two lengths. Long and bit less than long haha...

    Check them out before you decide what to do...

    Roy Ken

About RV Tips & Tricks

Looking for advice before your next adventure? Look no further.25,191 PostsLatest Activity: Apr 06, 2026