Packard Forum Index » V-8 (1955-56)

I'm have problems with the gas gauge, water temp gauge and the oil pressure gauge working intermitten when I start the car. When they do work they fluctuate! I have replaced the dash voltage regulator twice and the same thing happens. It has been suggested that I put a ground wire from the gauge cluster to a good ground to be sure there is a good ground. Does anyone else have any suggestions?

What car do you have? If several gauges are intermittent, it suggests a poor ground at the gauge cluster. If the gauges have a dedicated contact in the ignition switch, it could be faulty. It might also be worthwhile to be sure that all fuses are good and making good contact.

I believe the only years that used an instrument voltage regulator were the 51-56 models having King-Seeley thermal type gauges. 55-6 models are supplied from the ign sw ACC terminal, thru a fuse on the under dash block, then to the regulator input on the back of the cluster. 51-3 regulators are powered from the GA terminal on the ign sw and thru the switched 10 amp AUX circuit breaker also bolted to the rear of the cluster, to the regulator input. 54 has an ign switch ACC terminal like the 55--6 switches but has the 10 amp AUX circuit breaker instead of fuses..

The gauges run on a stated nominal voltage of 5v which is provided by 6 or 12v on/off pulses out of the regulator. The regulator is also thermally operated and functions by opening and closing a contact to ground. Load determines the frequency and pulse duration of the 6 or 12v pulses and when the actual voltage on time is averaged, the result provides the nominal 5v value. Because of the short pulses an ordinary VOM may not be fast enough to convert and average the pulses to be able to accurately measure or display the output. Here is what the instrument regulator output looks like when running on 12v.




Unlike the earlier magnetic gauges used in some models, the thermal type gauges themselves do not need a ground but the regulator and senders do. Take extra care to ensure those all have solid grounds.. Make sure the regulator is tightly fastened to the cluster when adding your extra ground wire between the cluster and a cleaned and shiny area on the body sheetmetal. After removing and replacing a fuel tank many report issues with the fuel sender ground and teflon tape or sealant at the temp or oil sender also has caused issues.