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Does anyone know how to test a temp sending unit? the gauge in my m37 isn't working, I tried 3 different gauges, and I have continuity from under the hood to under the dash on that wire. I appreciate any help.
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i think as the temp goes up the continuity to ground should go down. completeing the circut and causeing more current to flow through the wires in the back of the meter which makes heat that heats up a little spring and moves the needle. so measure continutiy to ground then moniter it as the engine warms up and see if it changes? -
Try this:
Sending Units.
a. To test function of sending units, an ohmmeter with 0- to 7,000-ohm range is recommended. The following procedure applies to any sending unit being tested.
b. Disconnect wire from gage to sending unit at sending unit.
c. Connect positive lead of ohmmeter to sending unit and negative lead of ohmmeter to vehicle ground. (G, fig. 1). Caution: Do not connect ohmmeter to ignition circuit and turn ignition switch ON as ohmmeter will be damaged.
(1)Temperature gage sending unit.
(a) If ohmmeter indicates a zero reading when engine is cold, replace sending unit. Sending unit should indicate high resistance.
(b) Start engine, ohmmeter will indicate a lower reading as engine is warming up.
(c) Stop engine, ohmmeter will indicate a high reading as engine is cooling.
(d) Replace sending unit if readings are not as indicated in b and c above.Comment
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fixed it
turns out none of my spare 40 year old guages were any good, ordered one from saturn surplus, the modern one I got has a translucent plastic back, also is marked for polarity, which is nice. thanks for the help, mattComment
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