Back from the dead

Cant seem to solve this one. Slip light flashes, traction control activates at will regardless of conditions. If I stomp the brake pedal it clears up. Also, the brake pedal is very hard to push.
Here's what I've done
Calipers x4
Sensors x4
Rear wheel hubs
Abs rings
Master cylinder
Brake booster
Vacuum lines
Master to abs feed lines
Abs pump and module
Fuses
VDC switch
Clockspring
Gravity sensor
Gravity bled the brakes then
Pressure bled then
Two person manual bleed
I have NOT replaced the Proportioning valve. I don't see how that would make a difference with my issue.
Booster, master, feed lines abs pump and module, sensors all came from an 08 Maxima. They worked in the car. They were tested and confirmed working out of the car.
So yeah whatcha got.

Costee

Did you ever run a scan on the ABS?

Back from the dead

I did indeed. No codes. Everything functions normal. I had the thought last night to bleed the master itself again. Even though I bench bled it there still might be air