DANMAS@aol.com wrote:
<snip>
> Or, go to Radio Shack and buy a couple of 100 ohm resisters. Use one in
> series with the lead from the gauge and ground. You should get "about" half
> scale reading. use two in series for 200 ohms, and you should get about a 1/4
> scale reading. Use two in parallel, 50 ohms, and you should get around 3/4
> scale reading. Actual values are not important, only that the gauge responds.
> Stick the resister in your tool kit, and use them the next time you have a
> bad gauge reading problem.
I just tested two original TR3A fuel gauges, and found that they need
substantially lower resistance values. Of course, they've been knocking
about my parts box for many years, so the calibration may be somewhat
off, but they agree fairly well.
Results :
Full 65-70 ohms
3/4 58-60 ohms
1/2 40-42 ohms
1/4 22-28 ohms
Empty 0-5 ohms
So, for a TR3A (presumably TR2-3B), you could use a pair of 39 ohm
resistors. One resistor ~= 1/2 full, two in series = full, two in
parallel = 1/4. (Note : 39 ohms is a standard resistor value.
Obviously, 40 ohms would work just as well, but is not a standard
value. Trust me.)
Also, looking at the gauge face, the left hand terminal goes to the
ignition circuit (green), the right hand terminal goes to the sender
(green w/black).
Since Dan's info is probably correct for a TR6, I surmise that maybe the
later cars with voltage stabilizers also had different sender
resistances. If true, this could be another source of errors (mixing
early/late senders with early/late gauges).
Randall
59 TR3A "daily driver wanna be"
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