I strongly recommend investing a few bucks in an Alldatadiy subscription for your car and getting some sort of OBD tool so you can read codes. Some of these systems are so complex and expensive that you can't figure them out without information, and even then it's not easy.

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Chuck Taylor
Falls Church VA
'66 200, '66 230SL, '96 SL500. Sold: '81 380SL, '86 300E, '72 250C, '95 C220, 3 '84 280SL's '90 420SEL, '72 280SE, '73 280C, '78 280SE, '70 280SL, '77 450SL, '85 380SL, '87 560SL, '85 380SL, '72 350SL, '96 S500 Coupe