When I start the engine (applying light pressure to brake to activate start button), everything is fine
BUT if i apply medium to high pressure after start, I get a steady ABS warning symbol that doesnt go away. I removed and visually checked the wheel speed sensors, hoping one was knicked or had a broken wire. All appeared ok. Brake fluid level is ok. I do hear a clicking...or light thumping sound coming from inside the center counsel (probably in the tunnel) when i press the brakes. Is this a normal solenoid sound? Could this be my issue? What is making that sound? Brakes appear to operate normal. I did the pressure regulator (booster) test by pressing brake 20 times (with engine off). While leaving foot on brake, i started the engine and pedal dropped as described by service manual.

Any ideas? Brake accumulator?? Booster???

Thanks