are you using Marlin firmware? If so, I had a very similar problem with a bltouch using the probe connector instead of z endstop. It is a bug of sorts in the firmware. The option to turn off z endstop while probing is default to off so the machine is looking for a valid z endstop switch with +5v status as it probes. Easy fix is to use the endstop plug instead, harder is to find the option to disable endstop while probing. It isn’t in the normal config files for the marlin build, it is buried deep and I can’t remember off hand. I just used the endstop plug.