Chevrolet Low Cab Forward 4500 2019 Series Owner's Manual page 257

256 Vehicle Care
5. After connecting the cables,
start the engine of the vehicle
with the booster battery.
6. Slightly rev up the engine of
the vehicle with the booster
battery and start the engine of
the disabled vehicle.
7. If the engine in the disabled
vehicle starts, remove the
jumper cables in the reverse
sequence as they were
connected.