Need Reality Check on Trailer Wiring Issue

[Topzide]

I have a jumper harness to connect my car trailer. Put a 7-way receptacle on the trailer. This way, the connector isn't in the weather all the time. Plus, it's a theft deterent! Have wires crossed from normal, so a straight jumper won't work! Makes it easier to move with the tractor without wiring in the way. Just another look at another way to wire a trailer.

 

[D&D]

I double checked resistance between the plug contacts for ground & brakes. You would expect to see one ohm or less (1/4 the value for a single magnet). What I found is that I sometimes got OL (no continuity) even with the side of the probe pins making contact with the brass contact. Moving the probe pins around, pressing deeper, would then produce a reasonable value (between 1 & 0.8 ohms) I'm starting to think the plug is faulty & the contacts are not always properly connected to the cable wire. A new plug is starting to look like the way to go.

Check the splice area at the brakes and axle(s) for corrosion, damage, etc

 

[nikdfish]

Picked up a plug last night & put it on today.

I cut off the old one with enough length that I could match wire color with contact via the multi-meter. (no surprise, the blue brake line had sporadic continuity)

Stripped back insulation & trimmed wires in cable after threading through new plug body.

Crimped on ring terminals after adding heat shrink

Torched the heat shrink after all rings installed

Installed wires on plug contacts after checking color placement via the old plug. Turned out the color pattern was as expected, but better to check & be sure.

Reassembled the plug. Just for fun, placed jumper clips loosely in GND + brake contact locations. MM read 0.8 ohms, so brake connection looks good!

Have to wait for the wife to get back so I can test with trailer plugged into truck. Don't want to take it down off the jacks until I know the job is done. May also do a brake adjustment while up.

 

[nikdfish]

Test went well & I did a slight adjustment on the brakes. Did a road test checking response to different controller settings to find the "empty trailer" number. Should be all good for the next usage.

 

[grsthegreat]

glad you got it resolved

 

[grsthegreat]

ive been having issues with my 1994 dodge diesel ram trailer plug. its a combination 7 pin with the lower 4 pin. i think the mag chloride has eaten it again. this one is only 3 years since it was replaced.

i fixed it the old fashioned way. i bought a 2020 F150 to replace it.

its my work truck and the old 30yo one was giving me too many issues. that, and i was told by my mechanic the old girl is worth between 8 & 10 grand on facebook marketplace. they love that engine.