Ever since I got my manual transmission, my back up lights have worked intermittently. Lately they are not coming on at all. I recently pulled the console wood to gain access to the back up light switch. I get power to the switch when the ignition is turned on and I get power coming out the other terminal on the back up light switch when the switch is depressed. But at no time will the back up lights come on. What else do I need to check?