Originally Posted by lino

Gently wiggle the output pin. If any movement is detected, the sensor is defective and should be replaced. After June 1988 an improved part was made (stamped 6.88) even though the part number remains the same.

Also wrong wattage bulbs in the tail lights may have also be the culprit. Some light bulbs fit and look the same as our OEM MB bulbs, but are actually different and will cause the cruise control to not function properly.