Make sure the door software is V2R23, comm is plugged into Con3 not Con7 & JP5 is off. If you have 60 ohms then the termination resistors/ jumpers are off as they should be. CCH should be about 2.5 vdc to ground and CCL should be slightly lower like 2.4. If those are off the most likely cause is the CPU, if they are good I would try to use a spare shielded cable in the traveler. Also, If any of the plugs are not screw terminals make sure the spring connection is not on the insulation.
