1988 292SR1. All my portside engine gauges read low including voltage, temp, oil pressure, and even the fuel tank if I have the starboard engine off. Starboard gauges are good to go. Comparative actual readings were verified with other means, mechanical oil psi gauge, auxiliary temp gauge, and fluke meter. These are the original VDO. All the wiring is extremely clean with no corrosion or breaks. I ran a temporary ground today to see if that corrected it but there was no change. I am beginning to think there is an internal connection issue with one of the gauges that is causing the rest on the daisy chain to register low. Anyone experience this before?