Now you tell me!The lcd contrast pot will require initial adjustment in 99% of cases when the gauge is self built.
It's an easy step to overlook.
I strongly discourage pushing/fiddling with the button if the gauge is powered and whilst there is nothing on the display, as it is easy to set a mode you didn't want like + 32% current for instance.
That's a good idea please try it and report back.The +12 v. OBD line is connected to always-hot 7.5 a. fuse 18 in the under-the-dash fuse box. Would connecting it to a 7.5 a. fuse that is not always hot cause any problem? That would seem to solve the problem of the gauge power consumption.