Voltage Limiter

The limiter is next to the connector not inside the speedo. If one socket is missing it will
not affect the other lights as they are wired in parallel (12V) from the headlight dimmer
The odd looking prong next to the connector plug is a mechanical type voltage regulator, takes 12V and reduces it to 5V for the instruments. I would rewire to eliminate this if it even
stills works and replace with a solid state 5v regulator (google 7805) sold online or Radio
Shack about 2 bucks. Use one 7805 for each of the 4 gauges as they are rated a 1amp.
Also rewire and resoder all the PC board connection joints. I suggest you bench test the
dash before reinstall. basically you will have 5V on the one side of each gauge, the other
side of the gauge(s) will go the sending unit(s). You can use a resistor or variable resistor of
the appropriate valve to simulate the sending unit. Use your battery hooked up as the 12V
source.