88 lx brake light testing my patience

[pos88lx]

so i have 1 brake light out, the inner(trunk mounted on driver side) light doesnt come on.
i do get all parking lights,turnsignals,backup,licence plates etc. its just that 1 brake light.
it has 4 wires, red/bl , black , green/red , green/black . im guessing the green/r is the brake 12v wire but it isnt getting 12 volts. is that the failure sensor causing that? and where do i get one of those? the driverside sensor only uses 5 pins and the passenger side uses 6 pins, can i swap one for the other to test or are they completely different?
thanks for listening :)

[pos88lx]

correction, both failure sensors use 6 of 8 pins, the one on the driverside actually has a 7th (a white/blue wire) that doesnt hook up to any of the wires on the connector of the lights/sensor. the gr/r does not have continuity but does read low volts (.02) which is actually less than the +volts im getting from the ground. the ground should not have voltage should it?
im new to this electrical automotive stuff so im confused

[Dr_Snooz]

the ground should not have voltage should it?

Shouldn't but it always seems to. I don't know why.

You can test the failure sensors by following the instructions on p. 25-93 and 25-95 of the manual. I don't know the wire colors off the top of my head, but one of them is going to supply 12V under the right conditions. The ground wire is most likely going to connect to the outside of the bulb socket. If you're getting voltage and ground, then the next most likely failure is a bad socket. Have you tried wiggling the bulb in the socket?

[pos88lx]

It's definitely not getting the right amount of power to that 1 particular brake light. Bulbs and sockets all check out. Seems the voltage drop is on the failure sensor at the driver side tail light. I found where to get the parts, but I'm wondering which one that is because the site refers to them as left and right, and I'm not sure which side of the car is left/right. Or would it be better to purchase both and swap em just because?

[Dr_Snooz]

I would test the failure sensors using the instructions in the manual. Left and Right are with you sitting in the car facing forward. I've never heard of them going out, so I would only replace the one that's bad.