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1974 620 BCDD Wiring Diagram

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Trying to understand BCDD operation.


It sounds like the BCDD relay is energized when the Speedometer Switch makes above about 10mph.


However the Shop Manual Wiring Diagram shows something more complicated and confusing:


  • The BCDD relay does not connect to any of the 12 terminals in the Instrument Cluster Plug.


  • It does go to a square box symbol labeled "AMP" inside the box - the box has 2 other wires coming from it:  one to the Speedometer Switch and the other to Pin #8 of the 12 pin ICP.  What this "Amp Box" is makes no sense - it has 3 wires with no explanation.

I thought there might be a BCDD specific wiring diagram, but I couldn't find one.  (maybe I missed it?)





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