Test IVR

Can't speak to the terminals but assuming you have some load on the 5v side (small bulb) you would see jumping voltage (digital volt meter) if you have an analog meter you will see the needle go up and down but the needle should spend a lot of the time around 5 to 6 v

This all assumed it is an OEM mechanical unit. A newer electronic version would produce a steady voltage.
^^^This^^
Except IIRC one of the aftermarket versions also produces a pulsed output.
An oscilliscope would be best but an anolog meter will show it. I posted a video of in this post.
Gauge Cluster Issues/IVR

here is some more on bench testing
Bench testing rally gauges