Have 3100 and the coolings don't operate. Jumped the harness by the sensor and fan come on for a second and then kick off. Disconnected both fans and put a test light in both fan motor harness connectors, same result fans should be OK. Replaced the relays - same problem. Harness by the sensor plug in doesn't look the best and goes underneath the intake so I don't know the condition. Any thoughts on why the fans won't operate?