Here at our RV dealership, we haven't had any issues with the GM OEM controller, but we have had a couple of problems with the Ford versions.
It seems to me that the OEM controllers are a bit sensitive to the 7-way plugs. Both Ford trucks exhibited the same symptoms: flashing codes and shutting the trailer brake function off. Inspection of the trailers being towed showed no real problems. A brake magnet was replaced on each trailer. That seemed to solve the issues with one truck, but the other continued to have problems. Each time the customer would have a problem, he would stop, pull the trailer plug out of the socket, and reinsert the plug. That seemed to cure the problem for a while.
This customer then decided to replace the factory 7-way connection with the EZ Connector. This is a very nice, high-quality 7-way plug that is very moisture resistant. He hasn't had any more problems since.
Casey
1995 K1500 Tahoe 2 door, 6.5LTD, 4L80E, NP241, 3.42's, 285/75R16 BFG K02's; 1997 506 block; Kennedy OPS harness, gauges, Quick Heat plugs, and TD-Max chip; Dtech FSD on FSD Cooler; vacuum pump deleted, HX35 turbo, Turbo Master, 3.5" Kennedy exhaust, F code intake; dual t/stats, HO water pump, Champion radiator; Racor fuel filter