(1990 240 sedan, 231,095 miles?..) Sometime ago my speedometer and odometer started to become intermittant and then failed altogether. I removed the instrument cluster today and cleaned the connections, checked for power on the 3 pin connector at the speedo, got good 12.5 resting voltage with the ignition switched on; checked for ground on the 3 pin connector at the speedo (good continuity), went to the plastic box in the trunk and separated the connections. I plugged the forward ends together in the trunk and got good continuity (R x 1 scale on a Simpson 260) at the speedo end. Plugged the rearward ends together then crawled underneath and got good continuity at the sensor plug end. Restored the connections in the plastic box and shorted the sensor end plug contacts of the wiring harness together resulting in good continuity at the speedo end plug. Yanking, twisting and pulling wires makes no change. I'm not however, getting any sort of continuity through the sensor itself. I only have a Haynes that is very sketchy diagram-wise beyond 1984, but I assume that the speedo sensor is merely a coil and therefore should have some sort of continuity. Have I discovered the culprit?

Thanks