BTW im new to this forum and posted this same thing on others......you guys are the only ones to answer so far and helpful besides telling me to find a mechanic. so thank you.
just got the code u0121. fuses all look good. no water in the trailer plug and it does this with the trailer unplugged. it did however rain the other day and the lights and DIC read for the trailer brakes went away until i was a few miles down the road.
09 duramax. Service trailer light is on. Emergency brakes light, traction control, and abs lights on. No codes. Hubs are good. Getting no where on this either. Where should I start looking. Fuses look good to.