Our 2008 Sprinter came with the factory radio installed, a Sound 5 model, which is a pretty basic radio with an in-dash CD player. We have been debating to get a new radio, but decided to stick with the standard model but retrofit an aux-in headphone cable. We wanted to avoid Apple earphones for this particular application due to obvious technical reasons. It’s really easy to do and takes less than an hour. We ordered this cable on Amazon, and it works great. No need to buy an expensive one from Mercedes or Blaupunkt. Information (as always) came from sprinter-source.com, most notably the following threads:
So here were the steps: Using a flathead screwdriver, we pried away the face plate around the radio. It comes off fairly easily and is attached with 7 metal clips.
The radio is attached using 4 T-25 torx screws, 2 of which are obscured by the little “cubby hole” right underneath the radio. The cubby hole is attached with plastic clips on the sides. To get it out, we simply rattled the plastic piece out by pulling left and right. It came right out after 5 seconds of effort and no parts broke off. You can save yourself a lot of time if you’re not afraid to damage this part. Otherwise you can also follow instructions in the forum threads mentioned above. Once the face plate is off and the cubby hole out, simply remove the 4 screws holding the radio (2 at the top, 2 at the bottom), make sure you don’t drop them behind the dash (which is what happened to us on one, ugh), and pull the radio out. On the back you will see an empty slot that allows you to plug in the aux cable. There’s really no way to get it wrong, just make sure to plug it in the position furthest to the side of the radio.
In order to activate the aux connection, you will have to change a setting on your radio. After some frustration, we found that there are actually 2 manufacturers of this radio: Blaupunkt and Hyundai. You can see who manufactured yours once you pull the unit out as it will state the manufacturer. If you look at the face of the radio, the Blaupunkt version will have plain radio station preset buttons while the Hyundai version will have text on them for alternative functions. If you have the Blaupunkt version, instructions on how to enable aux-in are in your manual. You do this by 1) turning your radio on; 2) pushing the sound adjustment button (on the very bottom left) repeatedly until the display states “EXT”; 3) turn the volume adjustment button until the radio displays “EXT AUX.” While our manual showed these instructions, they didn’t work because we have Hyundai model. With the Hyundai model, it’s similarly easy but you have to get into ‘Hidden Test Mode’ to enable it. You do this by 1) turning the radio on; 2) pushing the sound adjustment button AND #4 preset button simultaneously; 3) pushing the ‘tune up’ button repeatedly until the display states “EXT”; 4) turning the volume adjustment button until the radio displays “EXT AUX”. Done.
This video shows how to do it:
Lastly, we drilled a hole into the plastic cubby hole for an easy connection of our phones, put the 4 screws back, pushed the cubby back in, and reattached the face plate. It works great. We’re also debating to buy a bluetooth connector for convenience – any recommendations? We’re looking at this one or this one so far.
Update: We ended up buying this bluetooth receiver.