Mercedes M Klasse Diesel Cruise Control Issue

I understand your frustration with the cruise control malfunction in your Mercedes. I had a similar experience some years ago with my Volvo. The cruise control stopped working, and like you, I suspected a fuse or wiring issue. In my case, it was a faulty brake light switch. While your Mercedes and my Volvo are different, cruise control systems are similar. Have you checked your brake lights? A defective brake light switch can disable the cruise control. Also, can you share the specific error code from your diagnostic tool? This might help find the problem.

Thanks for the quick reply I did check the brake lights and they seem to be working fine The error code is a generic one related to the cruise control system malfunctioning It doesn't pinpoint a specific component Do you remember if the Volvo gave a specific error code or was it also vague I'm trying to avoid replacing parts unnecessarily based on just a hunch

You are most welcome. The error code on my Volvo was ambiguous, not explicitly indicating a faulty brake light switch. Considering the non-specificity of the error code in your situation, and the fact that you have already verified the functionality of your brake lights, I would recommend a comprehensive diagnostic evaluation by a qualified technician. While I understand your inclination to avoid unnecessary component replacements, a systematic approach is often the most efficient means of identifying the root cause of such issues. A workshop should be able to pinpoint the exact location of the defective cable or plug connection.

Okay, I appreciate the advice. I took it to the workshop. It was a corroded connector on the speed sensor. They cleaned it, applied dielectric grease, and everything is working again. Total cost was 95€, which is way better than replacing parts Thanks again for pointing me in the right direction even though it wasn't exactly the same issue as your Volvo