A truck driver charged over the road death of an off-duty policewoman told another motorist in the minutes after the fatal crash that he knew his brakes weren't right, a court has heard.

Samandeep​ Singh, 27, is charged with culpable driving and dangerous driving causing death over a collision that knocked First Constable D'Arne​ De Leo from her motorcycle on January 12 in Wantirna.

Truck driver Samandeep Singh arrives at Melbourne Magistrates Court. Credit:David Crosling

First Constable De Leo was on her way to work when she was hit at the intersection that connects Boronia Road to the EastLink freeway about 9am, and dragged under the truck.

Motorists on Boronia Road that day told Melbourne Magistrates Court on Tuesday that they heard Mr Singh sound his horn several times as he approached the intersection, and then saw the truck drive through the red light and collide with the policewoman's motorcycle before the truck stopped.