Mystery Wire

imoto · 05-31-2015, 12:22 AM

Would anyone be able to identify what this wire is for ? Its on a 1981 SC the connector has a brown and white wire on one side connecting to a same colour wire and a green /black wire connecting to a green / black and a yellow and black wire ( not connected ) and showing bottom left. It does not look like it has ever been connect no loose wire and everything electrical seems to work on the car. Just curious about it really.

gerakroo · gerakroo's Garage

We just finalized the connection drawings for our new SC wire harness set but i cannot recall this connector (especially not at his location) can you follow where the wire's are going ? The wire looks black-yellow instead of yellow-black ?

imoto · 05-31-2015, 03:45 AM

Its night here now I will check tomorrow but I had to feel around behind the wiper motor and it goes into a loom. Yes I guess it is Black with a yellow trace.

gazzerr · 05-31-2015, 08:45 AM

It might be the spare lead for the rear foglight that came on Euro cars. I've got my dash blower out right now I'll see if I can find it on my 82 SC. I see you are in Oz so I'm assuming you are RHD. Maybe the looms were a little different on RHD v LHD cars.

gerakroo · gerakroo's Garage

In case of a rear foglight the wiring would probably be white/green.

imoto · 05-31-2015, 06:03 PM

Yes my car is RHD. I had a good look to see if I can see where the wires go but can see that the two on the side that has the "mystery wire"go into a loom that disappears behind the wiper motor. The back/green and the brown/white come out of a large loom going along right behind the dash behind the fog light,rear window demist switches and cig lighter into the connector in the photo. I can barely get my hand back in there .

SpyderMike · 06-01-2015, 03:54 PM

I would guess that it has to do with the brake light circuit. My reasoning:

1. The only black/yellow wires I saw when rewiring my car were for brake lights off the switches.
2. The schematic for 1981 SC shows a Black/Green with a companion Black/Yellow at a connection point in the front trunk. This has to do with the brake light circuit.

Do you have cruise control? If not, then that unused wire could end up to the cruise control module to disconnect during braking. Please put a meter on it to ground. When you press on the brakes does it show 12VDC +/-?

If you have cruise control, is it working properly? Does it disconnect during braking?

Power comes into the brake switches on the Green/Blue wires and is switched through to the Black/Green or Black/Yellow wires. In my experience, the Black/Green and Black/Yellow can look similar in color due to age/grime/etc.

Mike