There is a grounding bar connecting the three pods (instruments, speedo, tach/clock) together and then to ground (pin 1 on your connector). If the grounding bar connections have corrosion and thus no ground, these items will not work. You can take your cluster apart and clean the surfaces.

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1993 W124 300D 2.5L Turbo, OM602.962
2000 Chevrolet Cavalier, 2.4L DOHC
2002 Ford Explorer, 4.0L SOHC
2005 Toyota Prius, 1.5L

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