Any car can be subject to a failure of one of its vital parts. The Mercedes S class is known for losing all or some of its backlights. This may not be of concern when you are driving in the daytime but, the moment it gets dark it will become difficult, if not impossible to see the gauges. This means you are unaware of the speed you are going with.
The most common faults connected with the instrument panel on this vehicle are:
• Failure in part or full of the illumination
• The display becomes pixilated
• The speedometer will stick or will simply not work.
• The warning lights are usually accompanied by a buzzer. This sound often fails
• Complete power failure to the instrument cluster.
The most likely sign that you have a problem occurring or that one is developing is that one or more of the following symptoms will become noticeable:
• The gauges are completely black at night time depriving you of valuable information.
• The lighting is out but all other functions of the vehicle and instrument clusters work as normal.
• This fault can be a sudden occurrence or it can be a temporary, intermittent fault which gradually gets worse.
The usual problem with the S class instrument cluster can be traced down to a voltage issue. Like many vehicles the car needs to draw a little power, even when switched off and parked up; this is to keep the memory going which stores all the vital settings. However, if this draw increases, usually due to an errant sensor somewhere in the vehicle; it will deplete the ability for the instrument cluster to be illuminated. This over-voltage issue is not easily fixed!
How to Fix It
There are several methods open to you to ensure the car is fixed properly. Before you look into any of these methods it is essential to check the original documents of the car. Many Mercedes came with a ten year guarantee, which started when they first went into service; not when they were first registered. It is possible you will be able to have this fault fixed by your main dealer for free.
Your other options are:
• Purchase a volt and ohm meter and attempt to trace the electrical fault on the instrument cluster’s electrical board. This is a time-consuming process and, even if you identify the faulty part; you will need to remove it and replace it. This would require additional tools such as soldering and de-soldering stations. The instrument cluster on the S Class is complicated and difficult to remove to allow access to the various components. It is exceptionally easy to damage more of the components while you are working on it.
• Use a professional, independent specialist. These are firms which deal with issues like this, every day. They have the right tools available to quickly and easily locate and fix any issues, without damaging other critical components. This approach will be quicker and can even be cheaper than the cost of replacing components damaged by you during the repair.