D8t serial number KPZ01569. Brakes will randomly engage while in first gear. Only does it in first gear not second and only under 1400 rpm. I hooked a pressure gauge up to the brake pressure tap and have good pressure around 345 psi at low idle in neutral and while traveling in first gear. Most the time the pressure is good and no issues then randomly only at lower rpm the brakes will grab and my brake pressure will drop 100+ psi. What would be causing the sudden drop in brake pressure like that? And why only in first gear? Second gear doesn't do it. No codes come up. The transmission was pulled out and rebuilt. Clutches were worn out. It was doing this prior to transmission rebuild. I had the floor out and there were two wires on the same plugin that were bare going to one of the brake solenoids i believe it was for the secondary brake solenoid. So i fixed the wires and replaced all the solenoids on the brake control valve. It's like there's a current drop to the brake control valve but why only in first gear?