I found a post but gauge is different
What terminal does the blue and white wire go to on the datalogit

 

The white 0-5V output.

 

Which DL box do you have? Beige, black?


J.

 

black box

 

Better is to also go into the DL box and attach a ground wire that then comes out to a new ground connector. This then connects to the WB ground. Place a noise suppression capacitor across this ground to the +5vdc input.

This gets rid of the floating ground problem and also filters out input noise.
A WWS!

But I do not expect you to do this as you did not understand the wiring diagram.