W211 e500 obd2 reader code#
So given the above history there are three primary diagnostic code reading methods (actually four) that you may come across in the model year window of 1984-1999 (Please note all dates stated are approximate and for guidance only) What is a little confusing is that Mercedes in their wisdom used the 38 pin diagnostic connector for both the analogue and digital systems making it very difficult to visually identify what system you are dealing with – they even used the same pin number allocations to reflect the connection to individual system components ! Fortunately Mercedes saw the error of their ways and only ran with this for about a six year window opting to take on the OBD2 standard across the board from 1999 (Thank goodness!) Types
Even though the communications standard of ISO9141 is the same as used on OBD2 systems the way in which it talked to the modules was bespoke – and this is why you cannot use traditional OBD2 readers on systems of this type. This used both a K-line and L-line connection and Mercedes own communications language to access the system. Without going into too much detail this new system used ISO9141 communication protocol to access the vehicle electronics via a common communications module. From August 1995 production date Mercedes phased out the analogue type of flash/blink diagnostics in favour of their propriety digital code reading system. Mercedes were in parallel developing their own digital diagnostic system and not following the industry standard of OBD1/2. So very much a hybrid situation was in existence – seemingly done as a quick fix to continue to sell cars in the US.
At this time Mercedes added the OBD port under the dash, in some cases near the steering column just to give access to emission related diagnostic codes, all the other electronic systems were dealt with through the 38 pin socket as before. The reason behind this was that MB at the time had to comply with export requirements that necessitated access to emission data through OBD standard protocols. USA and some EU versions around 1994 were equipped with both a 38 pin X11/14 and the now common 16 pin oblong OBD port we use today. Although 38 pins were used only the pins relating to build options were loaded and as such gave diagnostic flash / blink access to the cars individual modules. This was commonly located within the ECU box and was accesses by removing a sealed access cap. Codes are resolved from comparison of flashes to fault codes on a written list.Ĭounting flashes activated by grounding individual pins continued through the square block connectors to the 38 pin round X11/14 diagnostic socket to about 1994. All was needed was a paperclip or short banana plug jumper to ground the required pins and simply watch the number of flashes. There were actually only14 diagnostic pins on some 16 pin X11/4 models as slot 2 was a small momentary push button and slot 4 was a small red LED used to read out fault codes flashes. The first being either through an 8 pin (X92) or 16 pin (X11/4) square block fastened to the bulkhead. Enjoy!Ĭarsoft Interface connected to R129 MB Diagnostic Historyīack in the day when Mercedes first ventured into the world of on board diagnostics in the era of the 1984’s W124 and its stable mates they began to introduce electronic code diagnostics. What I have done is written about the important parts and included some vital pieces of information that you may need to refer to – you may find this data at the other linked sources too, but at least it will remain available in another Mercedes resource should any of it disappear from the web, as a great deal on this subject already has. I will not repeat what has already been expertly written on this subject, you can find links below to these sources to expand on what I have noted here. Well the alternative information source you have been looking for is here, hopefully clear and accurate enough for your needs. I have collected the following information together in one place to save the frustration of trying to locate and find most that you would ever need to tackle this job. You will have also likely been frustrated by reading a multitude of confusing information, following dead web-links and generally reading several different takes on the same subject – mostly from well-meaning members on forums or online motor clubs who unintentionally ‘muddy’ obtaining the most correct and technically accurate information.
W211 e500 obd2 reader series#
Mercedes older series diagnostic fault code reading. W124.R129 1980’s – 1990’s eraĪs you are reading this you will probably be wishing to extract a fault code or clear a fault indicator lamp from the dashboard of your older Mercedes Benz model vehicle.