Speedo / Tach / Gauges: fuel and temp gauges appear to not work on my 1961 Lark

[ajalstude]

I'm stumped on this one. I just had my gauges and speedometer rebuilt and was told that my fuel and temp gauges were "shot." It appears that when a current from a battery pack was applied to the two contacts on the back of the Stewart-Warner gauges on my 1961 Lark, the needles wouldn't wiggle or move a bit. I bought two replacement gauges from Studebaker International, and the gauge restorers told me the same thing - that these were duds as well. They tested them in front of me and they didn't move a bit. After some thought, however, I am rather skeptical that both sets of gauges could be duds.

The man doing the work in the shop had two Double D batteries and two wires. He applied them to the fuel gauges of a late 60's GM model and got some action, but the same set up did nothing for mine, and I wanted to ask if he was doing something wrong when testing them.

Thanks for the help!

Albert

[StudeRich]

The OHM ratings of GM Gauges are completely different than the Independant Auto. Co.'s and Chrysler, so a comparison like that is pointless, not to mention that is NOT how you test them.

They work by having a regulated RESISTANCE applied to the Sender Terminal and 12 Volts to the Power (+) side.

[gordr]

Indeed. And the ground to the gauge case is an essential part of the circuit. Sounds like the shop guy is a little deficient on electrical knowledge.

[ajalstude]

Agreed - their forte is in speedometers and in cosmetic restoration. It appears that they don't know much about the electrical side of things. Good things to hear, though - it appears that I may indeed still have working gauges.

[karterfred88]

Two D batteries X 2= 6 Volts, no? 12 Volt car. Both gauges work by variable resistance. Check your wiring diagram. On my Avanti, the Temp, Fuel and indicator light on shifter are on one fuse. No juice-no work.

[gordr]

Apply +12 volts to the "ign" terminal of each gauge in turn. I believe they are marked. If not refer to the wiring diagram. Negative goes to the case. The pointer should not move. Now, briefly ground the other terminal. Within a second or two, the pointer should come off the zero peg, and head for the max peg. Un-ground it before it pegs out. If they do that, they are probably OK. And four D cells as the power source would probably work for that test. The "minimum" resistance for the sending units, which translates to gauge maximum, is around 80 ohms, and a direct ground at the terminal is close to zero.