I've got an '03 Sport with the non-Premium radio.

There are 3 harness attatched to it: the main harness, the one for the rear controls, and another one that, as far as I can see, has no purpose (I've tried unplugging it, and no difference whatsoever).

There is no external CD changer or amp/subwoofer (since this is not a Premium).

Before I install my new aftermarket HU, I'd just like to know what this last harness is for.

Anyone?

Thanks.

Any pics? My '03 Ranger only had one harness. Or you can go to your local shop, they should be able to tell you.

Sorry, I don't have a camera, but I got this shot of where the harnesses connect to from another website.

http://oem-auto-accessory.com/cgi-bin/image/templates/t100a.jpg

It's what is known as a T100 connection. The 2 bottom ones are the ones I already know --it's the top left one I'm trying to figure out.

It's a small square with only 4 wires.

So that was in the Ex? And you are putting am aftermarket in? If so, you will only use the plug with the power and speakers wires on it. The other two you will not use.

Yes, actually I already knew that --I had just wanted to know what it was for/what it went to.

Thanks though!!

Top left usually is sub power on and amp power on, as well as the signal wires. I'm not sure why you have something there if you have no sub. See if you can trace the wires. I'm curious where they lead.