I just received a KWP2000 Plus (from Ebay), but it is not able to connect to my Citroen C5 2.2 HDI '02 with EDC15C2. It reports only "ecu not found". On Citroen C5 1.8 '01 I can connect and read two numbers to the "ecu information" window, but that's all. Reading the original SW fails. I tried the "slow" setting too, no help. An OBD reader works nicely on both cars.

Is there a way to test the signals of the box? Any other tips to point out where the problem is?