2003 Ford Expedition install question

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I have an 03 Ford Expedition. It has a factory 6 disc changer stereo, and a drop down DVD screen for the rear.

No one makes a harness to integrate the DVD player into an aftermarket head unit.

There are 2 plugs on the back of the factory stereo. One is for the stereo itself, and one is for the DVD player. None of the wires in the plug for the DVD player have any power but when you unplug that plug from the stereo it kills the DVD player, so it must be a ground??

The plug also carries the signal wires to the factory deck. There is a red, white, black, green. There is one shield wire so they all must share one common shield?

If I splice rca plugs onto the signal wires coming from the DVD player itself is there going to be voltage coming from that player and I will need to use a converter?

Does the stock stereo have a built in converter or do you guys think the DVD player just sends a signal to the stock stereo?
Its a self contained unit but its a factory unit. You put the DVD into the drop down unit itself and it plays the sound over the factory system through the factory head unit.

The stereo shops tell me when you add an aftermarket head unit, the drop down DVD system is worthless. I want to figure out how to make it work. I have found the signal wires in the harness. I was unsure if the unit just sent a signal to the factory head unit and was amplified by the head unit or it actually sent voltage to the head unit.

I wanted to splice RCA jacks onto the signal wires then run it to an auxilary input on my aftermarket head unit.
Barring a head unit tear down and trace back method, you could see if the DVD player will play audio cd's as well (they usually do) and insert a test tone CD to probe the lines for signal referenced to ground. If you have signal on more than 2 wires, it's probably using a BTL output system although I'm going to doubt that but for informational purposes I thought i'd mention it. As for determining line level Vs. Amplified, it's safe to assume line but you can verify that with your tone level as well. You could also jumper the shield to the HU ground and see if that restores the power. Both pretty safe methods.

If you develop a way to do it, post it back for posterity. Good luck.
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OK thanks.

I can also probe the signal wires with my meter to test for AC voltage?

I have a hand held scope as well, I could play the test tone through the dvd player and test the signal wires to see what the signal looks like.

I just was not sure why they used only 1 shield wire to share between 4 signal wires?
Right, ok I will test the wires and see what I come up with.

I assumed they were all signal wires because when the head unit was on and I probed the 4 wires it made an interference noise through each speaker as I probed each wire.

The factory units are set up to do a dual play as well meaning the people in back can listed to the dvd player on the rear speakers and the people up fron can listed to the radio on the front speakers.

There are also rear controls for the stereo. I am thinking they have to use a control module of some sort some where?

I have a subscription to alldatapro and I have been looking over the wiring schematics but its confusing because they cover a few models in the same schematic so there is alot of perferated lines and ghost printing.
Ok got it to work but.......

I found the "system on" wire in the harness which hooks to the remote of the deck and turns the DVD player on.

I found the 4 signal wires in the harness from the DVD player and wired RCA jacks to them and hooked them to the auxiliary input of my deck which gives the DVD player sound through the newly installed system.

Problem is I have horrible engine whine and interference when the DVD player is playing through the system. I found the shield ground wire wrapped in foil in the factory harness but grounding it to various locations including the deck itself does not cure the noise.

Not sure how to get rid of the noise???
Hello seankane, I was reading your problem here and I have an idea. You said that you have 4 signal wires, did you mean as in 4 channels or 2 positives and two negatives. Because I do not believe that they would have a 4 channel input. you may just have 2 pos. and 2 neg wires. I would try wiring each to a rca and listen to them to identify which 2 are the same channel and use them as a match pos and neg to each of the rcas' to have just a 2 channel output. see if that gets rid of your noise.
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