Nissan Repair: 89 sentra tail light sensor, haynes manual, volt ohm meter

Question
part number 28425 77a00, how do i check if sensor is bad, having probs with brake lights not working, the third light in window is fine, the switch on pedal is fine, comes down to stop tail light sensor, witch is located in the trunk drivers side next to fender.  the part is dealer only $90.00, but if its not the prob i need to know before i spend a bill. help me out if u can and if i can find out how to test with ohm meter i can go to junk yard thanx

Answer
Brad,

I have not had the pleasure of doing one of these sensors.  But, if you say the high mount brake light works and the brake lights at the back are not working I would get a meter and check the output at the lights.  Then, at the sensor.  If there is no current coming out of the sensor and there is power coming to the input side when the brake lights are applied I would say the sensor is defective.  You could wire around it since you are getting current to the high mount light or get one from a wrecking yard.  I would assume that what you are getting on the volt ohm meter for your defective one would indicate what it should not read.  I looked this up in the Haynes manual I have an it does not even mention a brake sensor for your year or model.