I've done what I feel like is a fairly thorough search through older threads and could not find a clear answer:

Does anyone know of an aftermarket wiring Harness for 2007 Escape/Mariner Hybrids with NAV and the factory Subwoofer System? Thanks.

 

If Metra or Scoshe don't make a specific harness, it's probably because the external Ford Nav CD player and sub system are not compatible with aftermarket head units.
If you dig around the Internet you can find examples of people who used the factory sub enclosure space to install an aftermarket amp and woofer/driver.

 

I actually went to Car Toys yesterday and picked up a new head unit. I made them aware that I've read that it seems to be difficult to get the factory subwoofer to work when you replace the stock NAV unit, and they both shrugged like it wouldn't be a problem. They then told me it would be 60 bucks to do the install so I kind of told them to shove it and I'll do it myself.

Having said that I'm going to do the install tonight and I will let you know how everything goes.

 

$60 is not bad compared to others (not saying its a good price, just comparatively). Crutchfield quoted me several hundred because they said they'd have to manufacture a harness on the spot.

 

Ah I see.

Well I got the stock Nav out last night just to find out that the wiring harness that Car Toys gave me isn't even close to working. So I'm going to take it over there after work today and have them do the install. I've had a car in the past where one of the techs was able to to a hard-wire install without a harness adapter, so maybe they will be able to do that.

 

Just an update:

I took it back to Car Toys and had them install the new head-unit which had to be manually hard-wired because there is no adapter that fits.

Now the interesting part about the subwoofer: Apparently the "turn on" circuit that the amplifier will only use is a 6 volt line. I guess there was a 6 volt line coming out of the factory radio that it would use for some reason but the tech working on my car yesterday said he wouldn't put a 12v wire to it for fear of burning up the amplifier. So he said he would use a 500,000 Ohm resister to take 12 volts down to 6v. They didn't have a resister that large yesterday so I'm going to make one more trip over there so they can install the resister and we'll see if that get's the amplifier going.