Weak brakes & battery box confusion.

[Hay Dude]

I don’t *think* its the plug. The brakes worked for 1st 2 months, then rapidly became weak.

 

[nisaacs]

Over on the HD Ram forum they say one of the types of 7 wire trailer plugs is incorrect.

In the attached picture the correct version is on the right side.

I have trailers with both types, I prefer the double contact plug.

 

[ddbackhoe]

Wouldn’t that be in the 7-pin plug?
They do have a self tapper on the trailer itself

The 7 pin plug has a larger diameter wire (orange circle) that does go to the truck. One wire goes to the breakaway disconnect switch, one wire to the brake negative side. Where is the trailer actually connected to the truck wire? Probably the one zinc coated self tapping screw after it goes to the first set of brakes. You may find another self tapper (or two) on the rear by the lights.
As someone else mentioned, replace these with a bolt and nut, sand the area, then respray after assembly.

 

[ddbackhoe]

Over on the HD Ram forum they say one of the types of 7 wire trailer plugs is incorrect.

In the attached picture the correct version is on the right side.

They both will work, the one on the left gets a bad rap because the dual contacts sometimes get too wide. A little tweaking with a small screwdriver can remedy that.
I also tape the plug into the socket with a couple wraps of electrical tape, cheap insurance to keep it from falling out. The springs on the covers go bad too.

 

[JBF43]

I had the same sort of thing happen to mine one time. Worked great yesterday but not today king of thing. After checking everything wiring-wise on the trailer, especially the grounds, I traced the wiring back into the plugs and found one of the wires had come loose inside of the plug. Repaired that and checked all the other screws to be sure they were tight, and no problems since. May not be your problem, but something cheap and easy to fix if that is it.

 

[dodge man]

I’d Jack the trailer up and have someone step on the brake pedal and spin the wheels. A guess on my part but I bet some of the brakes don’t work, maybe one axle isn’t working, maybe only one brake of the four working. Probably bad wiring.

I doubt the break away battery is the problem though you probably need a new one. Those things don’t seem to last long. I take mine out and keep it on a trickle charger but I don’t use mine as much as you do.

 

[sandman2234]

The controller that came in my truck doesn't like to run my big trailer at the same setup as my smaller trailer. If I go thru the set procedure each time I change trailers, it does better.
David from jax

 

[OzzyDaveO]

Noticed trailer brakes are weak.
Battery box says “recharge” on battery, but battery is only 2 months old and electrical tester reads 12.4V
Brakes work, but don’t do a lot, even with brake controller fully cranked to 10.
The trailer is only a year old and brakes worked well when I first got it.

What should I start looking at? Wiring connections seem fine

The breakaway battery does not provided any braking capability under normal operation.
Looks like 2 issues.
a. the break away battery is not getting charged from the tow vehicle. It normally gets charged either from a dedicated cct from the tow vehicle, or off of the clearance lamp cct from the tow vehicle. Is your tow vehicle configured to supply charge to the breakaway battery on a dedicated cct or via the clearance lamp cct. You are going to need to chase the cct or ask the trailer vendor & who every wired your tow vehicle
b. elec brake functionality on the trailer can be impacted by:
1. controller settings (incl fuse condition)
2. trailer plug connection (clean & make sure they make solid contact on the elec brake AND earth cct)
3. actual wiring condition on the trailer - crawl under and inspect the wiring for damage

First up check the brake controller fuse, then check the trailers brake functionality use a multi meter to measure voltage with the controller turned to MAX setting & engages (not this may not be the normal usage setting), wrt to the wiring earth return:

a. voltage on elec brake cct on the back of the vehicle with trailer lead disconnected
b. voltage on elec brake cct on the back of the vehicle with trailer lead connected
c. voltage on elec brake cct on the trailer where the wiring splits to service each axle / wheel.
d. voltage on elec brake cct on the trailer where leads go into each trailer wheel hub

if you not getting 10V or more when the brakes are activated you have identified an issue from the brake controller to that point.

 

[CoyPatton]

Yeah should have been more clear: there’s 2 issues
1. Battery box says “recharge” but tester says 12.4V
2. Brakes weak.
No, they haven’t been adjusted, but what would have changed that much from using it for a few months? It only gets used 2x per week. May have used it 15 times since I brought it home in March. The braking power dropped suddenly

A good electric mechanic needs to dig into your battery issue. It could be the battery has a surface charge but no guts when a load is applied. It could also be an issue with how it is wired causing a repeated drain recharge cycle. Also there could be an issue with the onboard charger electronics in the box—if the box gives you messages it has a circuit board in the box.

The trailer brakes with a sudden drop off of braking power also sounds like an electrical issue. The same mechanic can check out those issues also, but if you have not, do a visual inspection of the brake wires from the plug on the trailer to each connection inside each wheel. One last point—stop running your adjust to max—you are putting lots of stress on pads and magnets by doing this.

 

[Hay Dude]

The truck activates my other trailer’s brakes perfectly.
I believe the issue is the trailer, not the truck.