Murhy switches are usually wired to interupt power to either the ignition coil or the injection pump solenoid. Easy way to bypass is to put a fused wire to replace the switch controlled output wire, disconnect the power out wire coming off the murphy switch and put it on a light. If your sure its not an oil pressure or overheating problem go ahead and weld with it untill the switch shuts off the light and do your testing. Murhy switch configurations can include a pressure switch on the oil galley, water temp, water flow that tell it something is wrong. You may want to screw a mechanical guage as a backup to avoid a major meltdown. Find a bud with a temp gun to verify the water temp or just put a thermometer in the radiator cap (carefull its not a leaking head gasket putting air into the cooling system giving a false reading to the guage)
Good luck
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