The oil pressure/water temp gauge on my early '71 240Z no longer works. I've replaced sensors and done all the usual tests for meter deflection (shorting against a ground) and it's kaput; I guess the gauge's voltage regulator. I have purchased a used replacement gauge on ebay that the seller listed as "working". The gauge did not come with the connector and I would like to temporarily connect wiring outside the dash to test the unit, before going further and pulling the dash apart.

Unfortunately, I have little idea of which terminals connect to the sensors, ground, and 12VDC source. Circuit diagrams have been no help at all as color codes are all over the map. Can someone with more electrical experience confirm my following observations (photo of gauge below):

1. Terminals "A" and "B" both appear to have plastic insulating washers separating them from the metal case. Both are marked "UNIT" on the case body. "A" leads to the internal workings (windings) of the Temp gauge, and "B" to the Oil Pressure gauge. I believe that these may be the terminals that connect to the respective sensors.

2. On this particular gauge, terminal "C" has been partially painted black. I think this may be a ground ( - ) connection.

3. Terminal "D" is isolated on the circuit board. It is also marked "IGN". Could this be for the 12VDC ( + ) power source?

Any help would be appreciated; I don't want to blow up a good gauge. Thanks.

Robert