Need Reality Check on Trailer Wiring Issue

[nikdfish]

I've run into an oddball issue with the brakes on one of our trailers. Three of our trailers have electric brakes, a landscape trailer, a car hauler and a dump trailer. The same tow vehicle used on all, a 2020 RAM with factory trailer brake controller. Everything is fine with car hauler & dump trailer. Brakes function as expected and use settings in the middle range. The exception is the landscape trailer. In the past, brakes worked but not strongly & required a max setting on the controller.

Currently I have zero brake response with the landscape trailer, but all lights (led) work properly. I jacked up the trailer with all wheels offf the ground for testing. I hooked up the RAM & had the wife depress the brakes. The brake lights came on but I could still spin all wheels with zero resistance. However, when I pull the plug on the brake away box, the brakes are set on all wheels & won't turn. The cable's brake wire & the break away box output wire both terminate on the same post in the junction box. I have checked continuity between the cable plug's brake contact and the trailer junction box brake terminal, and it shows good with zero resistance.

Does anyone have any insights with regard to further testing to find the source issue? I'm just about to the point of doing a plug & cable replacement to see if that cures it.

 

[grsthegreat]

Does the landscape breakaway control have its own battery?

 

[grsthegreat]

Have you tested continuity of the wires in the wire run from truck to controls. From pin inside plug to where it terminates. It has to be this wire. The brake lights use a diffrent wire than the brakes themselves. You may have done this, im just confused with the way its described….its probably just me

 

[nikdfish]

Does the landscape breakaway control have its own battery?

Yes.

 

[nikdfish]

Have you tested continuity of the wires in the wire run from truck to controls. From pin inside plug to where it terminates. It has to be this wire.

That was what I expected, but continuity from plug brass contact back to wire end that connects on the junction box was good.

 

[grsthegreat]

The fact that the battery locks the brakes, it has to be in the wire harness itself. Especially since all the other trailers are braking properly.

 

[nikdfish]

The fact that the battery locks the brakes, it has to be in the wire harness itself. Especially since all the other trailers are braking properly.

Yep, that's why I'm think about replacing plug, cable, or both. It would be simplest to just do the plug first & see if that does the trick.

 

[mrmikey]

Would the brakes being out of adjustment not cause the brakes to be less than effective? Thinking that way, the only way there's enough current to pull the brakes hard enough is when it gets a full 12V from the controller or in this case from the breakaway battery?

 

[grsthegreat]

I wouldnt think so. The brake controller gain controller can place enough charge thru to the brakes if hes turned it up. It runs brakes on other trailers.

Ive had so many issues with the male and female ends on trailer wires ever since our county started using magnesium chloride on the roads for ice control. I swear im replacing them every 4-5 years it seams.

 

[nikdfish]

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.

 

[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.