i used existing wires for the 12v constant and ground, and ran new wires directly from the guages to the ecu for signal. both guages power on correctly (tach goes down to zero, speedo jumps to mid-point and then back to zero with the odometer coming on). after that they do nothing. ive checked the wiring a million times but ill check it again. by the way, what do you mean by mark the continuity??