You might want to check the bulbs first. Being double filament bulbs if one of the two filaments is out it could be causing a bad ground or sending the incorrect feedback. If it works fine without the driving lights on but blinks double rate with the driving lights on then its most likely one filament is bad on the bulb. Its one of those things that it cant hurt to check it first instead of replacing the difficult thing first and working backwards to the easiest. I always find it a pain crawling under the vehicle to drain the blinker fluid so start with something easier first.
1986 190E 186K (For Sale)
(Maroon, Tan leather)
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(Brilliant Silver, Black Leather)
2002 CLK430 Sport 45K
(Brilliant Silver, Gray Leather , Birdseye Maple)