Bench testing rally gauges

Thanks guys.
So if you have a bad IVR, I guess you are changing the FUEL gauge. I have an issue with some of the gauges losing power and then coming back. Since I have my bezel out for re chroming I was looking to change the voltage regulator and now found out with the Rallye gauge setup it is par of the gauge. Just asking, what is the capacitors function other than the obvious ?