The downside... no matter how many places you ground the solid state regulator to the cast metal inst' housing, nothing is chassis grounded until that housing is chassis grounded. You'll need to add a ground jumper to batt' negative before attempting any bench testing. Reason being, If this type regulator isn't grounded properly It has no ground reference. It will pass full system input voltage straight through and out to all gauges. If the battery should be a bit low at initial start up there is really no guessing how many volts the 3 thermal gauges would receive. I always added an actual ground wire from inst' housing to the car chassis to insure a ground. In cases where the customer sent me their entire assembly for service I would strongly suggest my converting their amp gauge to a volts gauge. That volts gauge needs a chassis ground wire added also. My ground wire would link the IVR and volts gauge volts gauge ground and anchor at the lower screw of center pod. Approx' 4 inch length of wire went from there to male and female spade terminals so this added ground the wire could be unplugged like everything else on the panel. Then ground wire would terminate behind the left kick panel, more or less mirroring the factories ground wire behind the right kick panel. End user could place panel just close enough to make all connections and test everything in the car before ever installing any of the mounting screws or raising steering column into place. But hey, I spent 2 years developing and refining rally panel servicing before offering to the public. As far as I know, after 16 years I still don't have 1 dissatisfied customer.
