Sending unit voltage

[ScottRod]

while I'm waiting for the one dude to get back to me on selling me a sending unit, I was checking my wire for voltage...
Is is normal for the sending unit wire voltage to flucuate up and down?
With the tester or my voltmeter, it's as if someone is flipping the key on and off.
Just wondered if anyone has seen this before.

[Uncle Skip]

You should get a steady 4-5 volts there your little resistor on the back of the speedometer. I have a couple of good ones, as do others.
there should be steady voltage, no fluxuation.
U@ss

[ScottRod]

I'll check the connections. Thanks.

[Ford blue blood]

Scott those are "choppers". They provide a lower average voltage to the gauges which are simple current meters. It is normal for the voltage to "turn on turn off" when operating properly (at least in the older models).

[ScottRod]

Wait a tick...WHAT are choppers? The resistor thingy on the speedo?
I realize the gauges are just amp meters, but is the voltage supposed to do that or not. One says it should have a steady 4-5 volts and you say it goes up and down.
I can't find in the Chiltons where it says anything about it.

[Ford blue blood]

You are talking about the "voltage regulator", a rectangular shaped can about 3/4" long mounted to the back of the speedometer, has one wire in from the ingition switch, two wires out, one to the temp gauge and one to the fuel gauge.....in the older vehicles this "regulator" reduced the average voltage by "chopping" it. Points open and close (bi-metalic strip) turning on and off the voltage (current flow). Newer regulators are solid state and provide a steady regulated voltage. If you average the time closed to the time open through a load (the instruments and their senders) the gauge sees a reduced voltage (less current flow).

Bottom line, the stock voltage regulator in my 61 Uni provides a chopped voltage to the gauges and they both work like a champ.

[ScottRod]

Ok great.
Thanks Bill.