In fairness I use Avilec and they have always been pretty good. They have told me in the past if they can't test an ECU rather than some the less scrupulous companies there are out there who appear to say they have tested it, charge you and return with no fault found...

I suppose another way to double check this odd signal would be to remove the cam or crank sensor, leave it plugged into the crank sensor connector on the loom and check the voltage on the signal wire. Is it 0 volts? Then try passing a spanner or some metal object across its face and see if the voltage changes and if so what to. Repeat the test at the cam sensor plug. Let us know what the results are.