If you run across a 3rd Gen Prius (this was a 2011) with a customer complaint of Hybrid Warning light flashes on when foot is on the brake pedal and you have codes:
C2311 Communication Error from HV ECU
P085D Gear Shift Control Module "A" Performance
Then you will want to check and see if the vehicle has been wrecked in the left front headlight area. There are 2 grounds (Grounds A3 and A4) located just behind the bumper that are either loose or a bad connection is present. In this case the bracket had been replaced and the body shop has painted the bracket piece causing excessive resistance and thus the bad ground. Removing the paint and re-securing the grounds for a better fit was the fix for this condition.
C2311 Communication Error from HV ECU
P085D Gear Shift Control Module "A" Performance
Then you will want to check and see if the vehicle has been wrecked in the left front headlight area. There are 2 grounds (Grounds A3 and A4) located just behind the bumper that are either loose or a bad connection is present. In this case the bracket had been replaced and the body shop has painted the bracket piece causing excessive resistance and thus the bad ground. Removing the paint and re-securing the grounds for a better fit was the fix for this condition.