Learning the HARD way...
Join Date: Jan 2007
Location: Boston / Ft Myers Area
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Note that the Oil Pressure warning light, assuming that it conforms to ABYC, will be triggered by grounding the wire that comes out of the light. Put another way, there is 12V supplied to the light, which then goes through a NC switch (rated at 4psi) to the engine block, which should be a ground. If there is another path to ground (look for chafing of the wire, or something touching the leads at either end) the light will come on. I don't believe that ABYC has a specified color code for this wire, but if you add a gauge, the wire between the gauge and sender should be light blue.