There is some mystery surrounding the standard Mercedes Sound 5 CD Radio player found in later model Vito and Sprinter models I hope that this post goes some way to explaining them and my findings prove useful in adapting the unit for connection to an external mp3 player etc.
The Mercedes Sound 5 CD Radio unit exists in 2 versions as I am aware, the one made by Becker and the other Mobis (Hyundai) Both radios look similar and have the same controls, connections and layout but differ in their internal firmware – this controls the radio ‘behind the scenes’ – to the user, both radios operate in a similar way with a couple of exceptions. The other difference is the later Mobis HA1111 version of the Sound 5 (NG) plays a range of computer audio file CD formats that the previous Becker unit does not. The Mobis unit has secondary button function legends above the channel preset numbers – this is a quick way to identify the models as the early Becker unit does not have these button markings .
The Mercedes Sound 5 (NG) Mobis Version HA1111
The mystery of the radio is that it contains flash memory that holds a unique code, this code is communicated to the vehicle electrical systems (CAN-BUS) main processor to give the radio anti-theft security. The radio can be removed from the van and refitted without the traditional recoding once power failiure has occurred. It simply talks to the central system, says I am here, the code is recognised and the unit is allowed to function. Great !
If your radio breaks or becomes faulty, you buy a used replacement right? Well you can, but it will not work in your vehicle. You connect it, all is well… then after a few seconds the set ceases to function and displays ‘PROD’. What this means is that there is no longer a match between the radio flash code and that registered in the central vehicle contol system. (it is reacting as if you had stolen it from another vehicle!) Now, that wonderful machine that connects to your vehicle electrical system when you take it into a main Mercedes Dealer (The Mercedes-STAR Diagnostic System) is able to syncronise a new radio to your van but cannot recode an existing one… Great marketing…. So they will sell you a new radio that is delivered with a default ‘blank’ flash code which is open and accessible, further activated by the dealer to synchronise with your vehicles central controller via the CAN-BUS. You now have a new working radio !
If you have a 6 Disc changer or Auxillary audio device that uses the radio audio section, such as some types of phone kit, these functions are activated and enabled by the STAR diagnostics unit. (Also variable volume-with-road-speed option) So lets say you purchased a 6 disc changer for your basic Sound 5 CD radio and the function of ‘CDC’ was not already accessible through the user menu, then it will not work. It would have to be activated for you (with a £ charge) by the Mercedes agent. See here for information of how to enable Sound 5 radio options from the front panel without MB STAR and a visit to the dealers!
What replacement options are open to us then ! There are used/repaired radios available that have been re-flashed by Auto Electrical Repair Shops that have car audio workshops. This is carried out by connecting directly to the flash memory chip inside the radio and using a PC programming device erasing and and reloading a blank ‘default’ dump of the factory code. This basically returns the radio to a factory ‘new’ state that enables connection to your vehicle without the fatal PROD error. But there is a downside, if you had options enabled such as AUX or in some cases CDC then these will need enabling again by the Main Dealer using STAR. Most, if not all decoded ‘re-flashed’ radios do not contain any options just a basic load.
From my own expierience I have come to the conclusion that once the blanked ‘as new’ radio is installed it will function without the security enabled, this means that you can remove it and refit it to another vehicle without the PROD error as many times as you like. However if you go to the dealer to have options enabled, or possibly even a main service (although I dont see why unless the radio section of the dealer software is accessed) the STAR will synchronise the radio to the main system and the radio will once more be locked and married to the individual vehicle. (This is my assumption as there is no other reasoning behind how it can function)
Knowing the above details regarding the radio, the first thing to do is check your fitted Sound 5 has the AUX option enabled, below is an extract from the owner manual, follow the instructions given to try and select AUX – if it does not exist in the user menu, the option to have an auxiliary audio input is currently disabled. You could try to enable it yourself from the front panel ‘Test Mode’ – read about this here. If this did not work for you, it would need to be enabled at a Mercedes dealer with MB STAR service and diagnostic equipment. If however you have found the option or you have managed to enable it, then you may wish to continue reading, describing how to easily add an audio input for your external device.
Firstly take a look at the photograph of my Vito installation below (Becker Version), it was carried out quite easily using a 3.5mm chassis socket that was mounted in the area to the left side of the storage compartment below the radio. There is a large quantity of free space behind this area and it was chosen to prevent any problems with catching it, or the connected lead with your hand during gearchange. Space between the radio is restricted in the gear lever area to the right of the set as you will no doubt be aware, often radio preset 5 or mute can be frequently knocked and selected with a finger or knuckle during an upshift. If you need to know how to remove the radio from the dashboard see here. It describes the radio removal to replace heater control illumination lamp (Other Mercedes.Gen.In Post)
A simple cable can be made up between the 3.5mm stereo jack chassis socket pictured and the rear of the radio, plugged directly into the available ISO socket at the back of the set. Perfect connection to the rear of the Sound 5 is achieved by using a special ‘blue’ ISO radio connector and contact pins that fits into the top row of the radio connector block. This special blue connector ready made can be obtained here, you can either use it as it is – threading the cable through the dash somewhere – or do as I did and cut off the 3.5mm stereo jack plug and solder the wires to the rear of a drilled and installed 3.5mm jack socket. The choice is yours ! The 3.5mm stereo jack socket can be obtained from Maplin Electronic Supplies here. Shown below is all the information you require to connect the radio to the external audio device. Should you require just the blue ISO plastic female plug and pins to fabricate your own cable it can be found here. It is possible to carry out this complete useful modification for under £15 if you have the AUX option already enabled.
Mercedes Sound 5 ISO Connector
Mercedes Sound 5 mp3 connection lead wiring.