Pyrometer wiring problem - help?
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Pyrometer wiring problem - help?
Help from anyone?
A little oops when fishing in the wires for my Autometer C2 pyrometer. While pulling the connector up through the A pillar I got caught on something and I pulled the two pyrometer wires out of the connector (the red and yellow ones that are in the wire sheath).
The connector has 10 holes, the back of the gauge has 10 pins so no help there. The black red, and white wires are still in place. If we said the connector retaining clip is "up" and then number the holes 1 to 5 left to right the black wire is in #3 on top, the red wire is in #5 on top, and the white wire is in #2 on the bottom.
Problem is I don't know which of the seven remaining holes are supposed to have the red and the yellow.
And I don't know how to post pictures either!
Anybody have one of these gauges that could take a look and tell me which holes have the yellow and red from the wire sheath n them?
Thanks for any ideas!
A little oops when fishing in the wires for my Autometer C2 pyrometer. While pulling the connector up through the A pillar I got caught on something and I pulled the two pyrometer wires out of the connector (the red and yellow ones that are in the wire sheath).
The connector has 10 holes, the back of the gauge has 10 pins so no help there. The black red, and white wires are still in place. If we said the connector retaining clip is "up" and then number the holes 1 to 5 left to right the black wire is in #3 on top, the red wire is in #5 on top, and the white wire is in #2 on the bottom.
Problem is I don't know which of the seven remaining holes are supposed to have the red and the yellow.
And I don't know how to post pictures either!
Anybody have one of these gauges that could take a look and tell me which holes have the yellow and red from the wire sheath n them?
Thanks for any ideas!
Post Fiend
Joined: May 2006
Posts: 10,007
Likes: 4
From: Central Florida
I found this,
http://www.autometer.com/download_instruction/904a.pdf
http://www.autometer.com/download_instruction/651h.pdf
http://www.autometer.com/download_instruction/652F.pdf
Here is what you should have for instructions.
http://www.autometer.com/download_instruction/0593A.pdf
http://www.autometer.com/download_instruction/904a.pdf
http://www.autometer.com/download_instruction/651h.pdf
http://www.autometer.com/download_instruction/652F.pdf
Here is what you should have for instructions.
http://www.autometer.com/download_instruction/0593A.pdf
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Junior User
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Here is what you should have for instructions.
http://www.autometer.com/download_instruction/0593A.pdf
http://www.autometer.com/download_instruction/0593A.pdf
Thanks for the interest and effort!
I believe (I mean I think) the thermocouple yellow and red were one over the other at one end of the connector. Don't know if yellow over red or red over yellow matters, don't know which end of the connector.
If I knew yellow over red or red over yellow did not matter (would not harm the gauge) I might take a chance on trying them at both ends of the connector to see what worked. Guessing that the pins in the gauge are likely only connected at one end or the other, the other pins would probably go nowhere?
Maybe reversing red and yellow would cause the gauge to want to go backwards? Damage result? What if I unplug real fast if the needle starts to move backwards?
The other info sheets don't show the same connector, notice that two of them show specific places for red and yellow wires to go.
Post Fiend
Joined: May 2006
Posts: 10,007
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From: Central Florida
Here is my thinking to that. The probe should not be self grounded since it has two wires. Two wires, to me says that one is a signal/source and the other is a return. I am not exactly sure how the thermocouple works, but I have to imagine that the internal resistance changes depending on the temperature of the probe. Resistors don't normally care which way voltage flows.
You could verify that it is a variable resistor by using a DMM to meter the ohms from off, to idle, to some RPMs. You should notice a decent change as the EGTs change.
You could verify that it is a variable resistor by using a DMM to meter the ohms from off, to idle, to some RPMs. You should notice a decent change as the EGTs change.
Hotshot
Joined: Aug 2006
Posts: 17,398
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From: Whittier, CA
Reax is on the right track. First, make sure none of the leads are conductive to ground. None should be. The sensor just changes resistance relative to temperature - find the two leads that are conductive. Confirm by reading the resistance as you stick the sensor over a flame and watch it change. Polarity should not matter.
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Junior User
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Here is my thinking to that. The probe should not be self grounded since it has two wires. Two wires, to me says that one is a signal/source and the other is a return. I am not exactly sure how the thermocouple works, but I have to imagine that the internal resistance changes depending on the temperature of the probe. Resistors don't normally care which way voltage flows.
You could verify that it is a variable resistor by using a DMM to meter the ohms from off, to idle, to some RPMs. You should notice a decent change as the EGTs change.
You could verify that it is a variable resistor by using a DMM to meter the ohms from off, to idle, to some RPMs. You should notice a decent change as the EGTs change.
What do you think about my guess that only the pins on the female side (back of gauge) that are going to be used actually lead anywhere?
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So here's what the ohmeter shows - it depends which wire + and which - on the meter:
with pos. lead on yellow wire and neg. lead on red and wire ohmeter on the 200 scale
on startup 5.6
at idle 8.5
at 30 mph 10.7
with pos. lead on red wire and neg. lead on yellow wire and ohmeter on the 200 scale
on startup 6.0
at idle 2.9
at 30 mph .6
So polarity does seem to matter.
And I thought again about where I said I believe the two wires were one over the other. So if that WERE true the only place they could have been is the "left" end of the connector because the red wire is in the #5 hole on the top row.
We're getting somewhere, thanks for the ideas!
with pos. lead on yellow wire and neg. lead on red and wire ohmeter on the 200 scale
on startup 5.6
at idle 8.5
at 30 mph 10.7
with pos. lead on red wire and neg. lead on yellow wire and ohmeter on the 200 scale
on startup 6.0
at idle 2.9
at 30 mph .6
So polarity does seem to matter.
And I thought again about where I said I believe the two wires were one over the other. So if that WERE true the only place they could have been is the "left" end of the connector because the red wire is in the #5 hole on the top row.
We're getting somewhere, thanks for the ideas!
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Post Fiend
Joined: May 2006
Posts: 10,007
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From: Central Florida
That's peculiar. One way as temperature increases so does resistance, on the other way they are opposite.
Since your gauge is full sweep, I'd suspect the 6.0 ohm cold and 0.6 ohm hot would be correct. There is a 10x difference between the to ends of the scale. Where as the other way is only about double at temperature.
This helps alot, now with the gauge powered up, one of the pins you need should have a voltage.
Since your gauge is full sweep, I'd suspect the 6.0 ohm cold and 0.6 ohm hot would be correct. There is a 10x difference between the to ends of the scale. Where as the other way is only about double at temperature.
This helps alot, now with the gauge powered up, one of the pins you need should have a voltage.
Lead Driver
Joined: Sep 2007
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From: Scio, OR
This is what I remember from working for a company many years ago that used thermocouples.
A thermocouple doesn't use a resistive measure. A thermocouple is two dissimilar metals in contact with each other that generate a tiny amount of electricity. The amount they generate depends on their temperature. As I recall, the hotter the thermocouple, the more current it generates. The gauge would look at that current value and derive the temperature required to generate it and display that value.
Here is a pretty good description of how a thermocouple works.
Thermocouple - Wikipedia, the free encyclopedia
Hopefully this will be of some help. I believe the voltages involved are very, very small, so I don't believe that it would damage your gauge if you hooked it up incorrectly. However I can't say that with any certainty.
A thermocouple doesn't use a resistive measure. A thermocouple is two dissimilar metals in contact with each other that generate a tiny amount of electricity. The amount they generate depends on their temperature. As I recall, the hotter the thermocouple, the more current it generates. The gauge would look at that current value and derive the temperature required to generate it and display that value.
Here is a pretty good description of how a thermocouple works.
Thermocouple - Wikipedia, the free encyclopedia
Hopefully this will be of some help. I believe the voltages involved are very, very small, so I don't believe that it would damage your gauge if you hooked it up incorrectly. However I can't say that with any certainty.
Post Fiend
Joined: May 2006
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From: Central Florida
The type most automotive companies use is called a K type, which leads me to believe there are several varieties. However with your saying it would be easy to test. just set the DMM for volts, one wire would be a ground and the other a voltage. Which would make picking the leads very easy, the one that shows near ground gets the positive polarity and the one with a voltage would get the ground.
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Back from probing the pins
With the connector plugged into the gauge and the key in the run position I get pins 9 & 10 (last two on bottom row) both showing 2.48 volts. With key off they show 0.
Checking with the ohmeter again I find that pins 2 and 4 on the top row are both grounds.
The two pins (1 and 6 I'm calling them) at the left end do not show any volts nor are they grounds so my "belief" that the wires were both at one end of the connector is probably inaccurate.
So that kind of leaves one end as a ground and the other with voltage IF they were one over the other (again trusting my memory) in holes 4 & 9.
Or both with voltage if they were side by side in holes 8 & 9 - could that make sense?
With the connector plugged into the gauge and the key in the run position I get pins 9 & 10 (last two on bottom row) both showing 2.48 volts. With key off they show 0.
Checking with the ohmeter again I find that pins 2 and 4 on the top row are both grounds.
The two pins (1 and 6 I'm calling them) at the left end do not show any volts nor are they grounds so my "belief" that the wires were both at one end of the connector is probably inaccurate.
So that kind of leaves one end as a ground and the other with voltage IF they were one over the other (again trusting my memory) in holes 4 & 9.
Or both with voltage if they were side by side in holes 8 & 9 - could that make sense?
Lead Driver
Joined: Sep 2007
Posts: 8,180
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From: Scio, OR
Given what I wrote above, and that pins 1 and 6 are neither voltage or ground, I'd say that your initial assessment is correct and that these are the pins that would be receiving voltage from the thermocouple. The question still remains, though. Which is the yellow and which is the red.
Post Fiend
Joined: May 2006
Posts: 10,007
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From: Central Florida
Actually they could both be voltage. One providing a voltage signal, and one that has voltage so it can sense a ground. 2.48v is awfully low, so I might suspect that Dchamberlain is right, this is just a sensing voltage.
Lead Driver
Joined: Sep 2007
Posts: 8,180
Likes: 669
From: Scio, OR
That is, of course, if I understand how a thermocouple works. And I think I do, but I'm not 100% certain.