Temp & fuel gauges - what am I overlooking?

Uncle Bob said
It's on the bench and I powered it up. The light started flashing on the IVR, there was fluctuating voltage at the 2nd and 3rd studs, and at the 1st and 2nd pins past 12 o'clock. So there is continuity from power to IVR, from ground to IVR, from IVR to both gauges, and from both gauges to the connector pins.

The IVR came with a couple of resistors and sort-of-instructions on using them to test the gauges.

FWIW I saw something today saying to check the resistance across the gauge and it should be 15 Ohms. I don't know if that's right or not but figured it can't hurt so I put the DVM in Ohms mode and touched the probes to the studs. Both the fuel and temp gauges read open.

I've got a few things to do here but I will check back often to see if there are more ideas.

Ok.

lets keep going step by step.

First, put your meter in dc volts and measure the voltage using the cluster chassis as ground and connect the other meter probe to the second and third gauge posts as indicated in the pic of the cluster board in post 10.

You should get 5 volts.
Check back with your reading when you get a minute.

Edit. My reasoning here is to first establish that you have the proper voltage to the gauges. You have already established via your first post that the gauge pointers are deflecting when the sender wire is grounded.