Ouch! But how can you argue with 6,174 posts and a name like Peter? I've been at this long enough to have learned that it wouldn't be worthwhile if it were easy...

I don't think I've ever mistaken the cruise lever for the blinker. It doesn't flop and seems solid. I drove the car cross county and then used it locally there for a few months; when, after a while, I tried to use the cruise again and it didn't work. No symptoms, surging, etc. prior to that.

Thanks to all--this is a great site. I looked quickly at GBL but didn't see any easy answers there either; I'll go back and read everything. I'm not sure I want to take everything out in order for them to "bench" them; maybe I'll try that, but I suspect I can probably do it here in Denver also, and I'd rather buy something and put it in the hands of my trusty local mechanic... I'm eager for some road trips before winter!

I don't know, maybe 25 mpg or 650+ miles per tank of fuel? Not bad for a 5,400 pound car. But it has been a while since I've done any serious traveling in this one.

Edit: Here is the fast reply from GBL.

That sounds like classic cruise amp problems. At that medium mileage (it's not high for a Mercedes) it might not be a bad idea to look at the actuator as well. You can just pop them both out of the car and send them for evaluation and possible repair. The actuator should sit on the top of the engine on a diesel; we can email you a picture if you are unfamiliar. The actuator part number is probably an 002 545 86 32. If it has a longer-than-36-inch cord on it, it might be another part number. The part number is on the rectangular cover along with a date stamp.

Your amp, I believe, would be the 005 545 05 32 (with a coding plug.) You might ask your mechanic where these units are located in your car.

I hate to see you spend money on something that you don't need. That's why I recommend sending both units and we can make sure you're replacing the part that is actually the culprit.

Hope this helps. Please don't hesitate to email again or call our tech line (805 772-5127) from 0900-1700 PDT if you have any further questions or concerns.

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Their website says contact them and they can diagnose the problem. Their's is $195 plus shipping, but they also seem to offer a lifetime warranty, so I don't quite follow the interaction thing. The site also has thorough instructions on how to remove it.

Second edit: The lifetime warranty at GBL only applies if you replace them both and, of course, buy from them; you have to pay $150 extra for it. I don't understand the interaction thing but I believe those who know more than I do. Nontheless, I'm going to "risk" it and try replacing just the amplifier.