mystery bulb and wire - where does it go
 

so while trying to tidy up the wiring on the truck, ive came across this bulb and wire behind the instrument panel, ive tried tracing the wire and it goes into the big bundle of wires in the loom, I also tried looking on the wiring schematic that's pinned on this site, but I for the life of me cannot figure what it is used for and how to test to see if it turns off and on as it should from factory.

the wire looks to be gray/silver and the black you see on there is overspray from previous owner. my first thought was that it might goto the instrument cluster as a warning bulb, but all the holes avail are already taken and non of them correspond to that type of socket holder on the bulb.

http://i2.photobucket.com/albums/y27...ps530149f3.jpg

Re: mystery bulb and wire - where does it go
 

It looks like the AC/heater bulb to me. They are single wire with that housing to pop in to the hole in the back side. :chevy:

Re: mystery bulb and wire - where does it go
 

What Andy said

Re: mystery bulb and wire - where does it go
 

Yup! Mine has two-one on each side of the heater-A/C controller.

Re: mystery bulb and wire - where does it go
 

Nope, I've got the same bulb behind my cluster along with the two for the a/c control. I've not figured out what its for either. Mine is 71 with full gage cluster.

Re: mystery bulb and wire - where does it go
 

Into the stock am radio?

Re: mystery bulb and wire - where does it go
 

X4. That's exactly what it is.

Re: mystery bulb and wire - where does it go
 

Guess it's time to get my 6'5 325lb self under the dash again and see where to fit it in, the previous owners did remove the AC system to shave the firewall but did leave the control panel installed.

Re: mystery bulb and wire - where does it go