In order to replace the back up lamp switch in the zf s6-650 manual transmission, first raise and secure the vehicle. For the6.6l models , disconnect the back up lamp switch electrical connector ,for 8.1l disconnect the back up lamp switch electrical connector. Then, call off the back up lamp switch. To install the new switch, tighten to 20 nm (15 ft. Lbs) while ensuring that one adheres to the fastener notice in service precautions. For 8.1l engine, reconnect the back up lamp switch electrical connector, and for 6.6l engine, reconnect the back up lamp switch electrical connector before you lower the vehicle.