Date registered: Mar 2018
Vehicle: 1990 300E 4Matic, 1987 560SL
Mentioned: 5 Post(s)
Quoted: 104 Post(s)
A couple of questions/possibilities. Or maybe not. I don't know. Since cruise control is apparently canceled by the unit's reading increased resistance produced by illuminating the brake lights, and since jyuma's brake light switch is not working, could it also be possible that the cruise control unit is receiving an accelerate "signal" due to a short, or other electrical impedance being generated due to the brake light switch being "faulty"?
Or, I don't know how similar, or dissimilar the electrical systems on 560s, and 380s are, but I learned very quickly that on my 560, there is a separate wire connected to the battery's positive terminal via the connector tightening bolt, which runs directly to the idle speed computer, and if it is not tightened well enough (to conduct), the 560 will "idle" at 2,600 RPM. This happened after I only placed the cable on the terminal without tightening it as I was just going to move it around in the driveway.