Another trailer brake wiring problem

[Land Barge]

I used the trailer brake wire from the 4 wire brake controller found under the dash cover. It has 3 small gauge wires and one larger gauge (196a) stepped down to fit the plug. I appears to be the brake actuation wire to the rear plug at the 5 o'clock position. I'm using the (197) positive wire going to the NO contact to trigger with a positive signal.

My problem is that everything works re I've toned the wire front to back, ohm tested the wire, and it shows clear with 0 ohms, the Odyessy II controller recognizes there is a trailer attached, works and sends signal to the brakes. However when and after you start the engine a few seconds later if the brakes are applied more than about 0.7 strength it recognizes a ground fault and shuts down to save itself. Spoke with Valley today to verify wiring orientation. They said to check for errant reason for ground at plug but after I got of the phone I discovered I have a sealed plug. They also said that it's rated from 8-16 volts so having it charging should change things. Tried on my son's trailer with same result so I've ruled out connected trailer. You really can't test without trailer connected as it somehow knows and won't allow an output unless connected which is consistent with my pickup.

The drawing shows this as a direct line front to rear with the exception of a Trailer Brake 2 jump around the mid chassis harness that looks like it just jumps another wire around the harness.

Is there some condition that while engine running a relay is doing something weird for some other condition. Would there be another brake system that requires a negative signal to the brakes themselves? Seems to work until I start the motor.

I'd really like not to have to run a new wire front to rear but that's looking like the case.
Thanks

[Ray,IN]

Anything smaller than #12 wire may cause problems for electric brakes. A wiring tester is made that plugs in instead of the trailer plug, and tests each circuit for any issues. Any competent hitch installer should have one, as they also install controllers.

[Land Barge]

Thanks Ray, I assume the factory wire for the trailer brakes would be of sufficient size to the trailer?

I tried again this last weekend and so long as I don't start the engine things work manual even with gain up to 5.0. Having a hard time comprehending what's happening after about 10 seconds after the motor starts. If I hold the manual control on and shut off motor it returns to working. I must have some relay messing with this circuit.

About to give up and run a circuit front to back.

[Rex]

The wire Monaco uses for trailer brake controllers is a Negative lead. You need to run it to a relay, and have the relay apply 12 volts positive to your controller. Just use the 12 volt negative to operate the relay. That way the pacbrake will not apply your trailer brakes, only your foot brake will.

The signal wire Monaco uses is called Brake Sig and should come from your front run bay from Monaco Box 1, 2, or 3.

[Land Barge]

Rex,
I hear what your saying but unless 197 starts out as positive and then goes to negative after the key cycle it's confirmed with test light and voltmeter as positive.

Which also shouldn't affect when manually activating brake controller. I also pulled the fuse that activates this relay to isolate the trigger circuit as to only manipulate by hand.

I found this to be the wiring configuration on mine as stated in this bulletin and reverse as stated.
Service Bulletin for Monaco Pre-Wired Coaches (Unified Tow Brake)

All that being said, I haven't driven fast enough to see if that circuit goes active with the pacbrake.

[Land Barge]

Just returned from a quick trip. Low and behold my new brake controller was bad. After hours of testing, convinced a new controller would be good, validated the signal to trailer wire was in fact good. Swapped controller from my other vehicle, which I should have tried sooner.

Short story, bad controller. Thanks to all who contributed.