Mystery Wire... Does anyone know what this does?
 

Today I was removing some of the leftovers from a defunct alarm system and came across this wire. I know it came from the alarm but what it leads to I don't know. It is an original wire I think. I've looked through the diagrams and there are a few notes for a solid Yellow (which is what this is) wire but none seem likely in that location. Where it disappears tt goes up the pillar as far as I can tell. Interestingly, I started the car and ran it today and the climate control worked (meaning Blowers and everything). I tested this line with a mullitmeter and it seemed to be carrying 2.5x volts. I capped the line with electrical tape before putting the side entry metal covers back on. Now the climate control blower doesn't seem to be working. Could this wire grounding through the body of the car before I capped it have completed the circuit that the alarm guy messed up? Is this a coincidence? Inquiring minds want to know!

https://cimg8.ibsrv.net/gimg/www.jag...fb5a4e10a6.jpg

I've never seen a yellow wire in that area. Certainly not loose like that. None under the back seat or under the center console either. it must be something somebody added.

Correct...that is not a wire original to the car, and is almost certainly related to one of those very troublesome after-market alarm systems...which just might account for the climate control involvement. These additions were always installed by people unfamiliar with the Jaguar and that led to many odd results...I cannot remember how many of these systems I removed from the Series III cars but I can remember the no-start problems they caused.

Gregory, the only factory yellow wire I can think of is contained in the Radio power harness.

Right Jose...and this isn't it. The photo also shows that the yellow wire has been amateurishly connected to a black extension. Clearly something cobbled together, and definitely not "Jaguar".

Everyone's right here, but maybe I haven't been clear. I know the black wire is amateurish. It went to the old alarm system that came out. A year ago I just pulled the whole alarm and all the wires except two that went from the left driver well (behind the carpet bolster) and then back. Yesterday I wanted to pull out the last wire. When I took the bolster out I found two wires. One was easy to pull (the one I was looking to pull originally which was in the trunk). I found this one. The yellow one seemed like an original wire. Why would an amateurish alarm guy splice his crappy black wire with heavier gauge yellow wire right there? More likely, I thought, the yellow wire connected with something underneath the d/s dash or in that bolster.

Because he ran out of one color Right There, and being a rank amateur, spliced in any scrap he found.
I have had my fingers into nearly all the wires in my car, and as Jose says, the ONLY yellow one feeds the radio.
There are some yellow with tracers, but only One plain yellow wire.
(';')