+1 to all posts above; however I don't believe the red/black plugs are OE, though still probably for the radio.

Also, check the hazard switch to make sure it is in the "off" position. If somewheres between on and off the signals act up.

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1982 240 D, 308,000 - 321,127 miles (sold)
1982 300 TD,166,500 - 226,000 miles
1998 E 320, 120,000 - 144,000 miles
2005 C 230 K, 26,000 - 77,000 miles (sold)