Before programming a control module, make sure there is proper voltage in the vehicle system with battery voltage greater than 12 volts and less than 16 volts and apart from that, no charging system issues like shorted Ignition Switch or loss of battery voltage as all must be resolved prior to programming a control module. If the voltage is low, the battery should be charged and connecting the battery charger is not allowed, to prevent programming failure or control module damage because of the wrong system voltage or the fluctuation. Deactivate any system that might rely on the battery power, such as the twilight sentinel, interior lighting, daytime running lights (DRL), hvac systems, and engine cooling fans. The ignition is to be in the right position as prescribed by the scan tool and in programming it should not be altered that is the position of the Ignition Switch unless led through. Make sure the connections of all the tools including rs -232 and connection at dlc are good and do not disturb the harnesses of the tool while programming so as to avoid interuptions that may cause a failure or damage.