The Back Up Light Switch circuit is controlled by a plunger-type switch that is screwed into the base of the transmission housing on its left-hand side on 5-speed transmissions and into the front of the transmission housing on 6-speed transmissions. If a fault develops in the circuit, first ensure that the circuit fuse has not blown. To test the switch, disconnect the wiring connector, and use a multi-meter set to the resistance function or a battery-and-bulb test circuit to check that there is continuity between the switch terminals only when reverse gear is selected. If this is not the case, and there are no obvious breaks or other damage to the wires, the switch is faulty and must be renewed. For 5-speed transmissions, firmly apply the handbrake, then jack up the front of the vehicle and support it securely on axle stands. Drain the transmission oil, disconnect the wiring connector from the Back Up Light Switch, unscrew the switch from the transmission, and remove it. For 6-speed transmissions, remove the air cleaner assembly, the battery and battery tray, disconnect the wiring connector from the Back Up Light Switch, unscrew the switch from the transmission, and remove it. To refit, apply suitable sealant to the switch threads, and then screw it back into the transmission housing. Tighten the switch to the specified torque, then reconnect the wiring connector and check the operation of the circuit. Where applicable lower the vehicle to the ground, and top-up/refill the transmission oil as applicable.