Well sure Andy, hopefully on the right track. If the ECU does not show CTS data then checking the CTS wiring between the CTS and the ECU for continuity, shorts and opens would be where I would go next.
To the OP. If you check continuity to the ECU with a light or multimeter (Ohms), unplug the ECU connector so that you don't fry the ECU. Sending voltage down a data line and into the ECU can cause some expensive damage. In fact to do those 3 checks on the wiring with any certainty you need unplug the connectors at the CTS and the ECU.
Continuity test in a nutshell:
An important application is the continuity test of a bundle of wires so as to find the two ends belonging to a particular one of these wires; there will be a negligible resistance between the "right" ends, and only between the "right" ends.
The last part is significant because you could assume continuity because you get a continuity indication when in reality you have shorts to ground.