Failure in CAN 1

[Lloret]

Hello good, we are testing sending control signals from the computer to the ECU through a cable that 
transmits CAN signals with a specified USB. Having the ECU connected, just when we connect 
CAN 1 the ECU is disconnected. We believe that it is a specific problem that we have 
not yet found with the wiring, but checking the connections we have not found electrical continuity 
problems. Do you know what could be happening?
From the port communication I only use CAN H and CAN L of CAN-1

[Adamw]

It sounds more like you may have some wires connected to the RS232 pins which will interrupt PC comms.  Make sure there are no wires connected to Tx/Rx.

[Lloret]

Thank you for the response. I have tried to disconnect these cables maintaining only CAN and ground connected, and the problem is still happening.

Does the ECU recognise the contacts on the connector or something like this?

[Adamw]

5 hours ago, Lloret said:

Does the ECU recognise the contacts on the connector or something like this?

If any wires are connected to the rx/tx pins and have more than about 200mm length they will add enough capacitance to upset the PC comms.  You need to ensure only the 2 CAN wires are connected and nothing else.