Jumped t/y wire gry/red. Motor runs strong. Red lt went off completely; hasn't come back on.Orange abs lt. only comes on when engine starts(then goes off normally),but when I press the brk. pedal abs lt comes back on. I test drove it and brakes work well for a while. After a few brakes pedal starts getting a little stiffer to where brakes almost completely quit working. Checked reservoir and it is full and has overflowed. I again jumped t/y-gry/r, motor runs, fluid level starts dropping back down to normal. I've replaced multiple brn. relays. on donor car the relays and everything functions properly. I bled the brakes(might need rebleeding). Can't figure out what is allowing fluid to back flow into reservoir. Any suggestions? Thanks!