Question about temperature gauge operation..
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Pro
Joined: May 2003
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From: Nottingham
Question about temperature gauge operation..
To all you menders of instruments..
I'm presently going through the gauge/sender system on the vette, to make sure it's indicating the right temp.
I've been looking through the wiring diagrams, and although I understand pretty well how the system works in principle (ie, sender resistance gets lower as coolant warms up, giving a bigger voltage drop across the gauge), I'm still a bit unsure of what exactly is going on inside the gauge itself. To me, it would seem logical for the temp gauge to have two terminals.. one for power in, one for the wire to the sender, but looking at the diagrams it seems the gauge uses a third, ground, terminal. What's happening in there?!
This is all purely out of interest, I'm just letting my curiosity get the better of me, really. The main point of the excercise was to see how accurate the gauge is against a k-type thermocouple, but this question has made me go off on a tangent!
Cheers
Theo
I'm presently going through the gauge/sender system on the vette, to make sure it's indicating the right temp.
I've been looking through the wiring diagrams, and although I understand pretty well how the system works in principle (ie, sender resistance gets lower as coolant warms up, giving a bigger voltage drop across the gauge), I'm still a bit unsure of what exactly is going on inside the gauge itself. To me, it would seem logical for the temp gauge to have two terminals.. one for power in, one for the wire to the sender, but looking at the diagrams it seems the gauge uses a third, ground, terminal. What's happening in there?!
This is all purely out of interest, I'm just letting my curiosity get the better of me, really. The main point of the excercise was to see how accurate the gauge is against a k-type thermocouple, but this question has made me go off on a tangent!
Cheers
Theo
Melting Slicks
Joined: Aug 2003
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From: Dayton Oh
[QUOTE=theoUK]To all you menders of instruments..
To me, it would seem logical for the temp gauge to have two terminals.. one for power in, one for the wire to the sender, but looking at the diagrams it seems the gauge uses a third, ground, terminal. What's happening in there?!
/QUOTE]
theo, the sender makes ground to the engine and therefore the wire running to it is actually receives voltage from the guage.
To me, it would seem logical for the temp gauge to have two terminals.. one for power in, one for the wire to the sender, but looking at the diagrams it seems the gauge uses a third, ground, terminal. What's happening in there?!
/QUOTE]
theo, the sender makes ground to the engine and therefore the wire running to it is actually receives voltage from the guage.
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Joined: May 2003
Posts: 601
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From: Nottingham
Thanks for the responses guys.
berserker..
I'm not sure the gauge's ground is anything to do with the sender, as marshrat says, the sender grounds through itself, via the block.
The lighting is dealt with on a different circuit entirely, that is all part of the cluster lighting circuit.
marshrat, I get what you're saying. The voltage on that sender wire depends on the changing resistance of the sender, and that voltage then sets the voltage drop across the gauge. I get that bit fine, it's the *internal* wiring of the gauge I'm unclear about, and how it actually works. Any ideas??
berserker..
I'm not sure the gauge's ground is anything to do with the sender, as marshrat says, the sender grounds through itself, via the block.
The lighting is dealt with on a different circuit entirely, that is all part of the cluster lighting circuit.
marshrat, I get what you're saying. The voltage on that sender wire depends on the changing resistance of the sender, and that voltage then sets the voltage drop across the gauge. I get that bit fine, it's the *internal* wiring of the gauge I'm unclear about, and how it actually works. Any ideas??
