EGT gauge wiring help
05-07-2005, 02:53 PM
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EGT gauge wiring help
New Auto Meter with TRE probe and 9' of TRE SS wrapped probe wire. There's a total of six wires to hook up. Two for light, two for probe and two that I have no idea what they do (bottom pair on the picture).
Anyways, the gauge only reads a maximum of 220F and only creeps up there when the ignition is OFF. As soon as the car is turned on, the needle drops right away and will move slightly when I give the car a little gas.
I've redone the wiring several times, running 10awg power wire from the under-hood fuse box. A friend suggested it’s a grounding problem, but my ground is tapped in the same ground as the light and the light works just fine.
A guy in a searched thread had a similar problem and was never able to figure it out. I noticed the Auto Meter instructions say the probe wire included in their gauge/probe kit shouldn't be cut or it will affect gauge accuracy, but doesn't specify an exact probe wire length for installing another brands wire. The TRE instructions don't specify anything either.
Any ideas? What's the purpose of the pair of wires outlined in red in the pic?
Anyways, the gauge only reads a maximum of 220F and only creeps up there when the ignition is OFF. As soon as the car is turned on, the needle drops right away and will move slightly when I give the car a little gas.
I've redone the wiring several times, running 10awg power wire from the under-hood fuse box. A friend suggested it’s a grounding problem, but my ground is tapped in the same ground as the light and the light works just fine.
A guy in a searched thread had a similar problem and was never able to figure it out. I noticed the Auto Meter instructions say the probe wire included in their gauge/probe kit shouldn't be cut or it will affect gauge accuracy, but doesn't specify an exact probe wire length for installing another brands wire. The TRE instructions don't specify anything either.
Any ideas? What's the purpose of the pair of wires outlined in red in the pic?
05-08-2005, 04:34 AM
#3
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Re: (lean)
The pair of wires outlined in red power the electronics in the meter that signal condition and ice point the thermocouple signal. +12 should be switched by your ignition switch.
The reason you don't cut thermocouple wire, is non instrument experienced folks then introduce different materials, solder, crimp connectors, whatnot into the system that have different thermo-electric properties. You can splice TC wire with thermocouple connectors and such, which are made of the same material as the wire. For Type K TC's One conductor is Nickle-Chromium (+lead and yellow) and the other Nickel-Aluminum (- lead and red). The connectors would be made of the same.
Here is a primer on thermocouples: http://www.omega.com/thermocouples.html
here are your color codes: http://www.omega.com/techref/colorcodes.html
The reason you don't cut thermocouple wire, is non instrument experienced folks then introduce different materials, solder, crimp connectors, whatnot into the system that have different thermo-electric properties. You can splice TC wire with thermocouple connectors and such, which are made of the same material as the wire. For Type K TC's One conductor is Nickle-Chromium (+lead and yellow) and the other Nickel-Aluminum (- lead and red). The connectors would be made of the same.
Here is a primer on thermocouples: http://www.omega.com/thermocouples.html
here are your color codes: http://www.omega.com/techref/colorcodes.html
05-08-2005, 10:30 AM
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I did use the crimp connectors instructed to and supplied with the gauge, but it was not specified to put one on a certain wire.
I used some di-electric grease on most of the splices and terminals, as I do with all electrical connections. Would that stuff have an affect? I used no solder.
Where would I find the ignition switch wire?
Modified by lean at 7:48 PM 5/8/2005
I used some di-electric grease on most of the splices and terminals, as I do with all electrical connections. Would that stuff have an affect? I used no solder.
Where would I find the ignition switch wire?
Modified by lean at 7:48 PM 5/8/2005
05-08-2005, 07:10 PM
#6
Re: (lean)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by lean »</TD></TR><TR><TD CLASS="quote">bump</TD></TR></TABLE>
um look up a couple posts. I think big moose gave you pretty good advice so you should take it. If you cant find switched power in your car you have bigger problems.
um look up a couple posts. I think big moose gave you pretty good advice so you should take it. If you cant find switched power in your car you have bigger problems.
05-08-2005, 07:27 PM
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Re: (Bailhatch)
Thanks, that makes it worthless post number 3127 for you.
He gave me advice, I asked him new questions. I can't read minds and therefore will not assume di-electric grease, which is very commonly used by electricians, will have an adverse effect on my thermocouple voltage readings.
The only bigger problem I will have is using the wrong wire, which is why I played it safe and ASKED. I have no problem in pulling over to get directions. So instead of your smartass comment, you could have typed less and actually shown you know what you're talking about instead of just trying to look like it.
He gave me advice, I asked him new questions. I can't read minds and therefore will not assume di-electric grease, which is very commonly used by electricians, will have an adverse effect on my thermocouple voltage readings.
The only bigger problem I will have is using the wrong wire, which is why I played it safe and ASKED. I have no problem in pulling over to get directions. So instead of your smartass comment, you could have typed less and actually shown you know what you're talking about instead of just trying to look like it.
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05-09-2005, 06:34 PM
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Anyways, I redid the wiring for about the fifth time. All di-electric grease was removed, cut new ends on all wires, all auto meter supplied crimps were removed, the lower wire positive feed was moved from a 12v+ (per auto meter instructions) to the ignition 12v+, redid ground several times and still the same damn thing.
I turn the car on, gauge drops to dead bottom. When the car is turned off, it instantly raises, but only to about 50* this time. I played with the ground and disconnected it while the car was running and the needle immediately jumped back up to about 50* and stayed there until I connected the ground again.
Any other ideas?
I turn the car on, gauge drops to dead bottom. When the car is turned off, it instantly raises, but only to about 50* this time. I played with the ground and disconnected it while the car was running and the needle immediately jumped back up to about 50* and stayed there until I connected the ground again.
Any other ideas?
05-09-2005, 09:00 PM
#9
Re: (lean)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by lean »</TD></TR><TR><TD CLASS="quote">l have is usingThanks, that makes it worthless post number 3127 for you.
</TD></TR></TABLE>
bump
</TD></TR></TABLE>
bump
05-10-2005, 12:25 PM
#10
Honda-Tech Member
Re: (lean)
Dielectric grease will not make a difference. It prevents oxidation.
I'm not trying to be a smart acre here but lets go step by step...
Ok, the end of the thermocouple wire has a functional thermocouple juction on the end of it right?
How do you tell you might ask. Disconnect the red and yellow wires from your meter and check them with an ohm meter. You should measure a couple (2 to 6) ohms. The resistance should not be critical for this type of meter design. What we are looking for is that the thermocouple is not OPEN. That is infinite resistance.
On one of there boards I showed closed ball and open ball thermocouples. The end of the TC should have the cromel and alumel wires spot welded together. This is the sensing TC junction. It may be open ball (the fine TC wires are out in the open air) or closed ball (the wires are TIG welded into a "closed ball" with the stainless steel sheath material.) If you need pix I could upload a few.
If the TC checks out OK, then the meter is kaput.
Good luck it has to be frustrating for you...
I'm not trying to be a smart acre here but lets go step by step...
Ok, the end of the thermocouple wire has a functional thermocouple juction on the end of it right?
How do you tell you might ask. Disconnect the red and yellow wires from your meter and check them with an ohm meter. You should measure a couple (2 to 6) ohms. The resistance should not be critical for this type of meter design. What we are looking for is that the thermocouple is not OPEN. That is infinite resistance.
On one of there boards I showed closed ball and open ball thermocouples. The end of the TC should have the cromel and alumel wires spot welded together. This is the sensing TC junction. It may be open ball (the fine TC wires are out in the open air) or closed ball (the wires are TIG welded into a "closed ball" with the stainless steel sheath material.) If you need pix I could upload a few.
If the TC checks out OK, then the meter is kaput.
Good luck it has to be frustrating for you...
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