300SD Cruise pulses to beat of blinkers

1984 330SD I have noticed that when I run with cruise on it behaves perfectly. However, if I signal a lane change with the cruise on the cruise control "pulses" the enginge speed exactly to the rythm of the turn signal. I can only assume electric but I am not sure as I am still learning MB behavior. It is kinda' funny actaully but is annoying (it is not voilent but it is like someone lifting the pedal and re-applying it) Thoughts? Doug in TX

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W126

1984 300SD Cruise pulses to beat of blinkers

Sounds like a poor ground between the cruise control box and speed signal source. I suggest cleaning the electrical connectors at the cruise control box and at the other ends of the wires if you can locate them. The signal light current flowing through the ground return path to the battery can cause small voltage changes along the path if the the ground wire connections are not good low resistance connections. Somewhere in the circuit, the current for the signal light and the current for the cruise control are going down the same wire. Current will flow on the path of least resistance, so if the lamp current can't go on the wire it is supposed to go into, it will go on any other path it can find. So it may find a path through the cruise control. It would be good to also clean all of the signal light wire connections too. Hope this helps.