Terminology:

Open: Reads as neither a negative nor a positive, and has an infinite resistance.
Negative: Reads as ground, and has a zero resistance to ground.
Positive: Reads as 12 volts.

Specifications Sheet

A negative triggered circuit typically:

Rests at Open and switches to Negative

or

Rests at Positive and switches to Negative

A positive triggered circuit typically:

Rests at Open and switches to Positive

or

Rests at Negative and switches to Positive

Factory Settings

All eight auxiliary inputs come factory set as Negative triggers.

Here is how it works: When the auxiliary is Open or Positive then it will appear as OFF (or 0) within MyGeotab while when the auxiliary is Negative (grounded, 0V ) then it will appear as ON (or 1) within MyGeotab.

Inverting Auxiliary Logic within MyGeotab

Any of the eight auxiliaries can be inverted in MyGeotab by the end user by going to the vehicle properties, clicking on More Details and then selecting the Auxilairy Tab. Once on that tab you just have to click on the auxiliaries that you wish to Invert. What inverting will do is whenever it receives Aux OFF (0) from the device it will save it as Aux ON (1) and vice-versa.

Geotab Configurable

 Any of the the first 4 auxilairy inputs can be changed to be Positive inputs by Geotab support using a custom code. When this code is applied the auxiliary will appear as ON (1) when it is Positive and OFF(0) when it is Open or Negative.