There's a plug like that on the back of the speedo, but I would assume if your speedo works and the other instruments are otherwise ok that this isn't that plug but either for something else or it could be unused. Sometimes they used the same wire harness for all cars and options were pre-wired in if they were to be equipped then they were used and if not they were just tied up behind the dash...does everything else on your car function properly?

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Marty D.

2013 C300 4Matic
1984 BMW 733i
2013 Lincoln MKz