The back-up light switch is therefore mounted at the side of the case of the transmission. To test the system, the ignition key should be turned to ON position, shift lever to the reverse, the back-up should light up. If the lights do not come on, check the back-up light fuse in the engine compartment fuse and relay box. If the fuse is blown then there is a short circuit in the back up light circuit, thus the wiring should be checked. If the fuse is still okay, shift the lever to 'R' or 'Reverse', lift the car and thereafter support it with jack stands. At the back of the vehicle, remove the back up light switch connector and then perform an ohms check between the switch terminals, there should be continuity. In case there is no continuity with the shift lever in REVERSE, then the switch must be replaced. If continuity is present, probe for presence of voltage at the electrical connector: one terminal should measure having battery voltage with the key on. If there is no voltage, check the circuit between the engine compartment fuse and relay box and back-up light switch connector for open circuit. If voltage is present follow the back-up light circuit between the electrical connector and the back-up light bulbs and check for an open circuit yet, both the bulbs could be out. For replacement, lift the vehicle and if not done already place it on jackstands , remove the electrical connector of back up light switch and then using an appropriately sized wrench remove the mounting bolt from the transmission case. Place the new switch in the transmission case and torque it to the manufacturer recommended tightened torque to accomplish the installation in a sequence from which it was removed.