Experiencing issues with your Mercedes Benz odometer can be frustrating. Many Mercedes-Benz owners encounter problems with their odometers, ranging from intermittent failures to complete malfunctions. Recently, I faced a similar situation and, through some troubleshooting, managed to find a temporary reprieve. Here’s my experience which might offer some insights if you are dealing with a Mercedes odometer issue.
Initially, I was preparing to undertake a full odometer repair or even consider a replacement speedometer, thinking the issue was mechanical or electrical. Before diving into a complex repair, I decided to conduct one more test drive. During this test, I experimented with the trip odometer reset button. Gently pressing the trip reset button about halfway in, just before it triggered the trip odometer numbers to move, I noticed a faint spring sound.
To my surprise, after driving for about two miles, the odometer started working perfectly! The outside temperature was around 62°F (my car had been outside overnight), and I also turned on the interior heater to check if temperature fluctuations were a factor in the odometer’s behavior. This initial success led me to postpone the more involved repair, hoping the issue was resolved, at least temporarily.
However, Murphy’s Law soon came into play. The trip odometer began acting up again, although it did function for approximately 2.5 miles before faltering. Interestingly, I discovered that the main mileage odometer would continue to work as long as I periodically reset the trip odometer. This workaround, while not ideal, kept the essential mileage recording functional.
Determined to understand the root cause, I later removed the instrument cluster to inspect the speedometer mechanism closely. I checked the aluminum gear and the plastic worm gears, finding them to be in good condition. I noticed that the tenths of a mile indicators on the trip meter had some blackening on their faces. Using a drill bit, I carefully spun the speedometer counterclockwise to observe the mechanism’s movement. Everything seemed to move smoothly.
I proceeded to clean the blackened faces with a cotton swab and used compressed air to remove any debris. Continuing my testing, I used a drill to spin the cable socket at high speed. After this cleaning and testing, the odometer functioned correctly for an impressive 11 miles. I also reset the trip meter, and this time, the reset action was crisp and clean – a noticeable improvement from before. Throughout this process, I avoided using any solvents or lubricants, relying solely on cleaning and air pressure.
As a precaution, I also tested my spare speedometer. Interestingly, the spare unit was unreliable. Its gray aluminum gear spun freely without engaging the numbers, serving as a clear example of a truly loose gear. This comparison reinforced that my original speedometer was fundamentally sound.
After reassembling everything, I conducted a short test drive, and the odometer worked as expected. Only time will tell if this cleaning has permanently resolved the issue, but for now, the Mercedes Benz odometer is functioning.
A helpful tip: When using a drill to spin the cable socket, place strips of blue tape inside the socket. This prevents the drill bit from scoring or deforming the socket and allows you to monitor for any wear during testing.
During this process, I also noticed that my original equipment manufacturer (OEM) dash light rheostat was missing its retaining screw – something that had been the case since it left the factory. Despite being held tightly, I replaced it with an OEM screw from my spare parts. This small detail highlights the importance of thorough inspection when working on these classic Mercedes-Benz vehicles. While this experience offers a temporary fix, professional Mercedes odometer repair services are recommended for a lasting solution.
