Intermittent brake issues - D3 with Tek-P3

[AJU4]

I run a D3 with Tekonsha P3 wired like Sniegy's instructions. I tow a T-Van which has has standard electric drum brakes.

Problem is, while braking the right trailer tyre locks up intermittently.

I travelled 5000km to Fraser Island and back with no problems. Last trip was touring the long paddock up the Cobb hwy where it came on twice before I ended up switching it off to rid the problem so I could get home.

Where do I start??? I've checked wiring. I've had track trailer service the brakes, new drums, shoes and magnets. Because it is intermittent means it is hard to pin point!

Any suggestions welcome.

[Lotz-A-Landies]

My D4 had problems with feedback through the P3, locking up the trailer brakes and a complete set of fault codes.

All solved with a diode on the brake switch feed.