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1958-1982 Temperature Gauge Input Readings
Every week we get multiple questions about the sending units and the dash
temperature gauges. We have tested every brand of temperature units
available and feel that it would be better to let you know the input
requirements per gauge rather than the output of the sending units.
For years the Delco Chart was the accepted rule for checking all mechanical
gauges. Bad news is, this chart is wrong! All gauges do not require the
same input to reach a specific temperature. We've had a "Help and Repair"
page on the web site for several years and this chart was listed on that
page! I guess it's time for it to come down and this will be an update to that
page!
Another issue with all small gauges is the actual gauge condition. Inside the
inner workings of a small gauge, there is a spindle connected to a round disc
magnet! This magnet is floating in oil and if this oil is missing, dried and
thick it can change the reading and/or the responsiveness of the gauge.
(Ever see a fuel gauge move and jump at every tiny movement of a car).
Most temperature gauges that read wrong are not defective and the
problem is in the sending unit! If you purchased a new GM sender, take it
back! Today’s current service replacement sender from GM will not send
the correct ohms reading to the gauge. The original GM sender 1513321 was
replaced by GM p/n 12334869, the only thing halfway correct was the
appearance. If you cars shows hot, yet appears, drives and functions fine
then the problem is probably an improper sending unit!
Adding resistance (a resistor added inline to adjust the ohms reading) on the
sending unit wire is not the answer! The temperature gauges are non linear
gauges so adding resistance will allow you to dial in a gauge to one reading
only. You will be fine if you decide to add resistance and it is a quick fix
that will not hurt the gauge!
To make sure the temperature sender you have is sending the correct
readings to the gauge verify it with the charts listed below.
OK.. disclaimer time....
The following pages contain testing results on multiple gauges per year. In
most cases NOS gauges were used for testing to obtain an average. Your
Readings may vary and this is only our sample test! To correctly know what
ohm's input is required for your gauge, you'll need to purchase a linear
potentiometer and substitute it for your sending unit. Willcox is not
responsible for errors or any incurred damages including parts and/or labor.
The following information should be used only as a guide and your own
findings may vary! Use at your own risk!
1958-1960 Temperature Gauge Test results
Gauge Face Close up
Gauge
Unit tested: T106, T221, T227
58-60
Gauge Temp
or Face Mark.
100
1st mark (dot)
180
2nd mark (dot)
220
Input
OHMS
required
222
148
96
71
63
1961-1962 Temperature Gauge Test results
Gauge Temp or Face Mark.
100
1st mark
180
2nd mark
240
Input OHMS
required
282
150
96
80
62
Basic Wiring Schematic for 1958-1962 Temperature Gauges.
1963-1964 Temperature Gauge Test results.
Gauge Face 1963
Gauge Face 1964
Units tested: 1963 NOS T111 & 1964 T110 T109 and NOS T110
YEAR
1963-1964
Gauge
Temp or
Face Mark.
340
1st mark
180
2nd mark
240
Input
OHMS
required
100
170
128
96
68
1965 Temperature Gauge Test results.
YEAR
1965
TEMP OR
MARK
100
1ST MARK
210
2ND MARK
250
OHMS
274
109
79
65
51
1966-1967 Temperature Gauge Test results.
Gauge Face.
Units tested: T101 – T104 - T105
YEAR
1966-1967
TEMP OR
MARK
100
1ST MARK
210
2ND MARK
250
OHMS
274
109
79
65
51
1968-1974 Temperature Gauge Test results.
Gauge Face Note
1968-1971 Green Face
1972-1974 White Face
YEAR
19681974
TEMP OR
MARK
OHMS
100
1ST MARK
210
2ND MARK
250
220
109
79
65
51
1975-1977 Temperature Gauge Test results.
YEAR
1975-1977
TEMP OR MARK
OHMS
100
1ST MARK
200
2ND MARK
280
Center Gauge Printed Cricuit 77 and 78-82
340
281
79
56
38
1980-1982 Temperature Gauge Test results
YEAR
19801982
TEMP OR
MARK
OHMS
100
1ST MARK
200
2ND MARK
3RD MARK
Front Edge of
Red
Back Edge of
Red
1977 and 1978-1982 Center Gauge Cluster Printed Circuit.
793
219
146
103
85
69
59
And last of all.. face readings... that a gauge can tell you!
Copyright Willcox Inc. 2010 all rights reserved. Duplication with out expressed written permission
strictly prohibited. Willcox assumes no responsibility for broke or damaged parts caused by errors or
following these instructions. As with any repair, use your own judgment.