Packard Forum Index » Post-War (1946-54)

Both the gauges quit working at the same time on my 51 200. First they would fail intermittently, then quit all together. I pulled the instrument cluster out and found a loose wire going to the gas gauge and tightened it, but nothing. I think it is the voltage regulator.
So question one - how do you test it?
Two - source of new ones?
Third -any suggestions on what else to look for?

Any help would be appreciated.

Testing accuracy may vary depending on your meter and it's response to the rapid on/off of the regulator. The picture shows what the output looks like (12v car). By way of explanation, center line is ground and the straight line on each square wave at top is 12.6v. The short blips on top and bottom of each square is electrical noise caused by the contacts making and breaking. This one is cycling at the rate of roughly 1/2 second off, 2/10 second on. That short on, long off gives the instruments roughly an average equivalent of 5v constant. 6 volt systems should have a longer on time and may be easier to measure.

To try testing, when you turn on the key there should be 6v or battery voltage at the center terminal (measured to ground). If regulator is working, there should be 5v at the other terminal which feeds gauges also measured to ground.

Because of the rapid on/off, your meter may either be too slow to respond so you get no or a very low reading or too sensitive in picking up the electrical noise when contacts make. In that case, the reading will be very erratic & all over the place.

Napa has universal 6/12 input to 5 volt instrument cluster regulators although the terminals are not the same. Kanter lists the real thing (group 4.06282) for $37.00.

Attach file:

---

  (32.11 KB)

Cured by replacing the dashboard voltage regulator, using a NOS product.