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Discussion Starter · #42 ·
Dropping a quick update for anyone interested. My back-up camera is not functioning, but I am 90% sure it is a self-inflicted issue and not something related to the install of my Alpine HU.
Here is the summary:
1. You need a Sprinter wiring harness adapter from a good quality provider. In my case I chose PAC and have been very satisfied with the quality of the product and the tech support. I have also learned that Mid_City Engineering in Chicago makes a good product and people say they are super supportive.
2. You can just plug the PAC harness in and the steering wheel controls will work w/o any wiring changes. Your kit will come with a Fakra to USB and a Fakra to RCA for the USB and camera connections, respectively. I also needed a Fakra to male radio antenna cable and a Fakra to SiriusXM cable.
3. You will need to use your new HU's microphone for the phone which I placed at the bottom of my instrument panel, attached to the steering column enclosure. Someone more skilled than me may figure out how to tap into the Metris wiring to connect the factory mic to the new HU and SOS, but I used the new HU mic for the phone and the hack below for the SOS.
3. Here is the trick to maintain the factory SOS. There is a one mustard colored, one white and two black plugs inside the larger main harness plug that you join with the PAC harness. The white one has three wires, one clear, one brown and one white. One of the black plugs has the main and ground wires that are much heavier gauge. The other black plug has a white and brown wire that is the same gauge as the ones in the white plug, as well as a number other wires of the same smaller gauge. You want these smaller gauge brown and white wires. Now cut the clear, white and brown wires to the white plug and cut the matching brown and white ones from the black plug. Leave the clear wire from the white plug disconnected and splice the brown to brown and white to white from the two different plugs. This will make the SOS functional (I actually tested it) and it will use the factory microphone and audio will play through your speakers.
4. USB Dash Ports
a) Top USB Port: Per #2 above, you will use the provided Fakra cable to connect between the factory Fakra cable that plugged into the back of the factory HU and the female USB cable coming out of your new HU.
b) Bottom USB Port: If you want to maintain a charging port, you will abandon the stock cable that connected between the dash port and the Audio40 HU. In it's place you will need to buy a Fakra HSD (four pin) female charging cable to connect to the factory dash port and a 12v power source. I bought this one on Discount Car Stereo and spliced it into the cigarette lighter wiring in the bottom panel below the cup holders.
Factory Fakra Connections:
Green to camera cable
Black to radio antenna cable
Violet to SiriusXM antenna cable
Blue USB to USB HU cable
White USB to USB charger cable
 
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