Mercedes-Benz DSR inoperative troubleshooting, what is DSR?
Many Mercedes-Benz vehicles have the DSR (Downhill Speed Regulation) system and have off-road capabilities. Navigating hills off-road can be challenging, especially on difficult trails and loose terrain. Luxury SUVs by Mercedes-Benz also offer such features. With these capabilities, handling difficult terrains or encountering significant obstacles on the descent is easier. The Mercedes-Benz DSR feature simplifies by taking control of your vehicle’s speed, allowing the driver to focus on steering, throttle, and braking inputs.
Mercedes-Benz DSR features function successfully in many conditions but only operate at a specific speed range. This system adapts to the angle of the hill, providing stronger braking on steep inclines. Mercedes-Benz DSR can only be activated in the drive, neutral, or reverse gear position. A target speed can be set within the 1.6 kph to 18 kph range. Driving faster than 35 kph switches the DSR off automatically. The OFF message appears on the display; you also hear a warning tone when the indicator on the driver display goes out.
Common Problems
The most common problems that trigger DSR inoperative on Mercedes-Benz vehicles include:
- Defective ABS Wheel Speed Sensor
- Faulty ABS Pump
- Signal Acquisition Module (SAM) Failure
- Weak vehicle 12-volt battery
- Alternator or voltage regular issues
- Water damage or corrosion issues
What does DSR inoperative mean on Mercedes-Benz?

DSR, or downhill speed regulation, is an off-road feature that aids drivers going off-road downhill. DSR inoperative means the system is no longer available; a system failure or a low battery may cause this. A diagnostic tool or a full system scanner will determine the problem with your DSR being inoperative. However, consulting your servicing dealer for this issue with your Mercedes-Benz is best.
Important warning notes
The DSR will assist the driver during downhill driving. The travel speed is maintained and can be set on the on-board computer. The higher the downhill gradient, the larger the braking force applied by the DSR to a vehicle.
How to activate/deactivate DSR?

Activate -You can only activate the DSR feature while driving at a speed of below 30 kph. DSR can only be activated if the transmission is set to Drive, Neutral, or Reverse gear. Press the DSR button, and the indicator light on the switch will illuminate, or the DSR icon will appear on your dashboard display.
Deactivate – Press the DSR button, and the indicator light goes out. The DSR icon on your dashboard display will appear “off.” However, if you continue driving and exceed the speed of 35 kph, the DSR will automatically turn off.
How do you set the speed on your DSR?
You change or set the speed only when the DSR is activated. You can change the value between 2 kph and 18 kph. To increase the set speed, briefly press the cruise control lever to the pressure point. To set a higher speed, press the lever beyond the pressure point. Always pull over, put the vehicle in Neutral, and apply the brakes if you need some adjustments on the DSR feature. Changing the set speed while the vehicle is in motion is not recommended.
Safety notes
DSR is only an aid designed to assist the driver when driving downhill. Please be responsible for controlling your vehicle and assessing whether the downhill gradient can be managed. When activating the DSR, your vehicle may brake suddenly due to the DSR intervening. It depends on the downhill gradient and the difference between the current and set speeds in the onboard computer. The vehicle DSR feature may not always be able to keep the set speed, depending on the road surface and tire conditions. You could lose control of the vehicle and cause an accident. Always select a set speed suitable for the prevailing conditions, and when necessary, apply the brakes manually. Never go off-roading alone; always consult a professional off-roader or be accompanied by a skilled off-roader with experience in off-road trails.
References
- All About Mercedes-Benz’s Downhill Speed Regulation Feature: https://www.dubizzle.com/blog/cars/mercedes-downhill-speed-regulation/#h-mercedes-benz-downhill-speed-regulation-feature-explained
- Mercedes handbook: https://www.mercedes-benz.co.uk/passengercars/owners-manuals/en-gb/pdf/mercedes-glk-suv-2012-x204-owners-manual-01.pdf