Help debugging temperature gauge

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BruceDow
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Help debugging temperature gauge

Postby BruceDow » Sat Sep 15, 2012 1:32 pm

My temperature gauge has not been working this summer.

I just bought a new sender, thinking that might have been my problem.

Here is what I am seeing with the new sender:

Ignition on, cold engine ... Gauge snaps to "off the chart" hot
Ignition on, lead disconnected ... Gauge snaps back to "off the chart" cold

Is it possible that some wiring got reversed?

Does anyone have suggestions what I should/could be looking for with my multimeter?


Thanks.
B.
Bruce.

~~ Do what you love, and love what you do. ~~
~~ To me - only my boat is not yet perfect. Everybody else's is to be admired for I know the path they have walked (Dave Lott, 2010) ~~
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matt167
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Location: Prattsville Ny

Re: Help debugging temperature gauge

Postby matt167 » Sat Sep 15, 2012 1:47 pm

Are you sure you have the right sender? The temp causes the resistance to increase or decrease depending on the sender. Any electrical gauge is basically a volt meter, tuned to read the voltages there dealt with correctly, so the wrong sender can make a gauge read very wrong. If you disconnect and it reads cold, then your sender is designed to read no resistance cold, and it would have the opposite reading if you had a sender designed to read no resistance hot. There are also different ohmerage senders, and you need the right 1 for your gauge.. The way you have it, the gauge should be wired correctly

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kens
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Re: Help debugging temperature gauge

Postby kens » Sun Sep 16, 2012 8:07 pm

Yeah, the 'ohm value' of the guage and the sender have to be matched.
Are you 100% positive you got the correct sender unit?
Oak is over rated, everything about it takes extra time; then it warps, splits or checks !!! :roll:

Trackhappy
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Re: Help debugging temperature gauge

Postby Trackhappy » Sun Sep 16, 2012 11:53 pm

Set your multimeter to Ohms and measure across the terminals (or the terminal and metal case). It should read a value depending upon the type of sender. Warm the engine up and measure again. It should change one way or other. You can take it out and put it in a pot of water on the stove and do the same test whilst controlling the temperature and you should be able to find a specified value at a specific temperature.

What brand of gauges have you got? If you use Google and enter the gauge manufacturer and put sender resistance it will liley bring back some information on what the readings should be for that gauge. Tell us the gauge maker and preferably model or series and we will find some info for you.

This spec from a Teleflex dual station one:
3/8 in. Dual Station Temperature Sender3/8 pipe thread
339 OHMS @ 100 Degrees F
35 OHMS @ 220 Degrees F

This link is quite good:
http://www.jamestowndistributors.com/us ... ure+Gauges
By the time I have built a boat, I'll be ready to build a boat....

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BruceDow
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Re: Help debugging temperature gauge

Postby BruceDow » Mon Sep 17, 2012 1:14 pm

Awesome!

Thanks for the info and the link.

I'll try again next time I'm at the boat.

I'll use the Teleflex debugging guide, and I will compare the specs for the gauge to the specs of the sender I bought. (maybe the sender I replaced was not the problem)

Stay tuned.
B.
Bruce.

~~ Do what you love, and love what you do. ~~
~~ To me - only my boat is not yet perfect. Everybody else's is to be admired for I know the path they have walked (Dave Lott, 2010) ~~
Dow's Monaco Project


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