Hi Pete,
At 07:35 PM 3/4/98 -0700, you wrote:
>Atwell,
>
>Can't speak about the Spit but here is what I have found (so far) on my
>TR6. (I am attempting to diagnose what I believe to be a "compressed"
>range of my temp gauge - it only reads up to 1/4 at normal operating
>conditions). This info is based on some tips I received from Dan Masters
>after inquiring about temp gauge testing earlier last year. I connected
>the following resistance values to my temp gauge with the following
>results:
>
> 200 ohm - 1/4
> 100 ohm - a little over 1/2
> 50 ohm - all the way hot
>
>The connection was made by running a lead from the battery + to the
>resistor, and then to the wire attached to the sender (I pulled the wire
>from the sender). I have not had a chance to test my sender yet but will
>do so soon.
>
>Two observations on your findings:
>
>1. The general trend is consistent with mine, ie. lower resistance means
>hotter temp.
>
>2. The range of values seems quite high (my values were ohms not Kohms).
>Maybe your sender is fried?
That was my gut feeling, but who wants to spend money on guessing when the
List is at my fingertips?
> Or maybe there is something in the wiring
>that I am missing which would affect the Kohm values and these values
>really are correct.
The Kohm values are read between the male connector on the sender (wire to
gauge disconnected) to the engine block. That eliminates any "backwards"
path to ground thru the instrument or voltage stabiliser.
>
>In any event I would try the gauge test with the resistors. (You might
>already know this, but you can achieve the test with two 100 ohm
>resistors connected in parallel for 50 ohms and in series for 200 ohms.
>I used 1 watt resistors and they were fine - no overheating). At least
>this would prove if your gauge (or the wiring to it) is potentially at
>fault.
I measured the voltage at the sender to see if the circuit up to there was
OK. My measurements indicate to me that it is good.
>
>PS. Why would the sender have a pulse? I though it was just a simple
>variable resistor (actually a thermistor).
The _Voltage Stabilizer_ is what "pulses" the voltage on and off. Thats
why I mentioned that the gas gauge is OK -- it feeds from the VS too. You
wouldn't see the pulses with an analog multimeter (I don't think so,
anyway...just an "average" of about 10 VDC).
Battery --> VS --> Gas Gauge --> Temp Gauge -->temp sender--> earth
--is how the current travels to indicate engine temp.
Maybe I'll see if an auto parts store can let me check a new sender
(non-LBC). If the resistance is low that will verify that my sender is bad.
(I don't have any resisters to try Dan's test.)
Thanks,
Atwell Haines
'79 Spitfire FM96062 UO
"47.5% of all statistics are made up on the spot."
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