VW Phaeton Cruise Control Fix: Check Brake Switch First

Had a similar issue with a 2007 Passat last summer. I have some experience working on VWs, mostly basic maintenance and diagnostics. The symptoms match exactly what happened with my car. After checking the blown fuse like you did, I noticed the brake light was also acting weird occasionally. Turns out the pedal switch connection was loose, causing both the cruise control and brake light issues. Took it to my regular workshop where they found corroded contacts in the brake pedal switch connector. They cleaned the connection points and replaced the faulty cable. Total cost was 95€ including diagnostics and labor. Before giving more specific advice, could you share: Does your brake light work normally? Are there any other dashboard lights showing up? Does the cruise control respond at all when you try to activate it via the steering wheel controls? These details would help determine if you are dealing with the same root cause or if it might be something else. Just make sure to have it checked soon, as faulty brake switches can cause other electrical issues if left unaddressed.

Thanks for checking. My brake light works fine and stays on when pressed. The only dashboard light showing is the cruise control indicator, which briefly flashes when I try to activate it using the steering wheel controls but then goes off immediately. Last service was done at 35000km and everything was working perfectly until last week. No other electrical issues noticed. The steering wheel controls for other functions like radio and volume still work normally. I will try to get those contact points checked since it seems like a common issue. Before booking a workshop appointment, is there any way to test the pedal switch connection myself with basic tools?

Thanks for those additional details about the symptoms. Since I dealt with this exact scenario on my Passat, I can share some more insights. Your symptoms sound slightly different from what I experienced. When my brake pedal switch was faulty, the brake lights were inconsistent. With your brake lights working properly, we might be looking at the speed sensor or another electrical component affecting the cruise control system. Before heading to a workshop, here are some basic checks you can do: Check the cruise control fuse box again, particularly fuse 15. Sometimes a blown fuse can look intact at first glance, Listen for any clicking sound from the pedal area when engaging cruise control, Test if the cruise control responds differently at various speeds, as a faulty speed sensor can cause intermittent operation In my case, despite the initial focus on the brake pedal switch, it turned out the speed sensor needed replacement. The dashboard light behavior you described matches this scenario perfectly. A workshop will need to run proper diagnostics, but based on my repair costs, expect around 150-200€ for a speed sensor replacement if that turns out to be the issue. Would you happen to notice if the speedometer works accurately? This could help confirm if the speed sensor is the culprit.

Thanks for the detailed suggestions. Yes, my speedometer works perfectly fine and shows accurate speeds, I checked it against my GPS to be sure. Really helpful to know about the clicking sound test, I will check that next time I drive. I rechecked fuse 15 and all others in that area with a multimeter, all testing good. No clicking sound when pressing the cruise control buttons, which seems concerning based on what you mentioned. The steering wheel controls feel normal, so hopefully the clock spring is not the issue. Given that the speed sensor seems to be working fine based on the accurate speedometer reading, I am wondering if this points more toward an electrical issue in the cruise control system itself. Would it make sense to focus the workshop diagnosis on the steering wheel controls and related wiring first? I will go ahead and book an appointment, knowing the potential cost range you mentioned. Just hoping to avoid replacing parts unnecessarily by giving them this additional information about what I have already checked.