Troubleshooting Airbag light

First gen taco. Airbag light flashes a code 31 and 12. Using the repair manual I have narrowed it down to either a clock spring or airbag sensor assembly. However, the manual is a little wonky. Troubleshooting these two codes always starts with this for the first step:



It also states to resolve with the codes other than 31 first. So I go to 12 first.

Starting step two, I'm assuming even though it doesn't state this, you have to reconnect the ground. How else would you be able to test for voltage?


The diagram looks weird to me, but I'm assuming this is two separate measurements?
The first being D- and ground and the second being D+ and ground.
I get zero volts if that's the case (although one of them shows .008 volts, but in my experience very minute voltage is normal in electronics).