Before I screw this up

[BrianX128]

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This is the only thing I've ever gotten the gauge to do. I took the top post off of the back because it's directly connected to the bottom post and when you take the whole black plastic thing in you can tell there are only three things going into the gauge, whatever is actually on the left side, whatever is actually on the right side, and one thing into the center post..

 

[laserjock]

Got me man. That's goofy looking.

 

[Macrobb]

Um... Lets see here:
A thermocouple is NOT like a resistance style sender. A thermocouple /generates/ power when exposed to heat - it's a very small amount, though.
You are talking somewhere in the 0-30mV range(0.030v) for a K-type thermocouple.
Non-amplified gauges use this tiny amount of power over time, and are slow to respond(You also must protect them from static electricity). These are the 2-terminal type gauges.
Amplified gauges and digital gauges use electronic circuits to read the small amount of voltage and amplify it as needed. These will require a separate 12V source to power the electronics.

Looking at yours(and the diagram I saw earlier), yes, you only have three terminals: 12V, ground(which is shared with the K-type thermocouple negative), and the thermocouple positive.

 

[BrianX128]

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So I should probably not be seeing this for my resistance.. I also really don't remember what I'm doing with this thing, but I think I did this right.

Either way I tried everything combination wise again this am with the gauge and it does nothing..

 

[laserjock]

That might be reasonable resistance. It's not copper wire you are dealing with.

 

[rwk]

check out this site http://thesensorconnection.com/content/egt-diesel-engine-installation-information
they have sensors, gages and alot of info, they have shorter t.c. then most, all made in US.
RWK

 

[BrianX128]

The other thing that I think put the nail in the coffin for this gauge and probe was if I set the multimeter to dc voltage smallest setting, the volts never changed from truck off, truck running, truck floored. Nothing.

Looks like I'll just be waiting until the isspro ev2 gauge I ordered gets here..

 

[Macrobb]

Just so you know, one K-type probe is the same as another(within a small margin of error; for us it doesn't matter).
You can always get /cheap/ K-type probes on Ebay that will do the job well enough; there are also gauges there as well.

That being said... I'd have to check with my HFT cheapy meter on a probe myself; I don't know if it has a low enough resistance to read that minor voltage.
The next-step-up HFT meter ( http://www.harborfreight.com/11-function-digital-multimeter-with-audible-continuity-61593.html - $23 ) has a dedicated thermocouple-reading section, and comes with a little probe.
(Off topic, but I have both types of meters from HFT. The $5 ones are good for most everything, but they don't handle the cold so well(the insulation on the leads cracks easily). The more expensive ones seem to be made of better materials)

 

[OLDBULL8]

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For the wiring of the gauge this is the diagram they gave me. When nothing worked, I went and hooked the 12v directly to the positive battery terminal. Ground to negative. If this thing works anything like I thought it did shouldn't the terminal for red to the thermocoupler have power? because I could touch that lead directly to metal and there was no spark as if the power wasn't actually going through the wires to the probe to begin with. I tried the black thermocoupler wire as well just to make sure and it had no power from the gauge either.

The wiring diagram doesn't even make sense though. Totally ignore the light power stuff, and just look at the "ground" and thermocoupler black arrows, those have metal touching each other so how would the resistance of the probe ever send a different signal to the gauge to begin with? This whole thing seems jacked up.

Either way, I think I'm almost over this gauge system. I have a 1/8 threaded hole in the exhaust manifold, I can fit probably about a 2 1/2 or so probe in it, anyone have a better suggestion for a known good gauge I could install in the hole that's already in the manifold without re-drilling stuff? I really at this point don't care what the price is for a better known good working system I just after messing with this thing this morning don't think it's gonna work period.

I don't see anything wrong with the circuit they sent you.

There shouldn't be any 12VDC Positive power to the thermocouple, it's generates it's own voltage from heat.

The light 12VDC Positive should come from the dimmer rheostat for instrument lighting or just 12VDC Positive when key is turned ON. Do NOT put the light Positive lead on with the 12VDC terminal.

The 12VDC Positive separate power is for the amplifier within the gauge.

The 12VDC battery Negative is common to both the light and the amplifier.

If you put Positive and Negative 12VDC to/on the thermocouple it may have destroyed it, it would be a short circuit, like touching the POS to the NEG terminals on a battery.

 

[BrianX128]

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I liked the isspro so much I had to get one myself and got it swapped out in mine today. Went and found the steepest hill near me and floored it in fifth (as best I could, old grandma in front of me didn't want to go 55 up the hill so I had to hold back some).

This thing is so much better. Immediate response to throttle and load / hill activity. Super simple setup and great materials come with it. Beyond pleased.

Now to get "three scoops" of gravel from the local landscaping place on my day off tomorrow and see how my egts respond. Highest we got in dads truck was 1000 hauling a decent work trailer up a steeper hill. I haven't got 1000 yet but haven't really worked it much..

 

[BrianX128]

Also, I just realized something very embarrassing that totally explains why my original gauge "didn't work"... You will all be laughing shortly, but I feel the need to post it in case anyone ever looks at the original gauge again on ebay as a cheaper option because it most certainly does work..

Look at where my egt's are at idle (I just noticed this this morning when going out to start my truck for breakfast that it was only at 200*, had a picture on my phone of this with the ISS Pro gauge)

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So.. If I rev the truck up sitting in neutral in the driveway, I can't get it to eclipse 300. Most I can get is like 275 ish..

Anyone remember where my original ebay gauge starts at?.... I got my replacement gauge from the seller and hooked it up to a battery...... 300F is where it starts..........

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It works. Exactly how it's supposed to. It actually seems pretty accurate too just by torching the probe and watching the gauge. Not as sensitive and responsive as the iss pro gauge is by any means, but it does certainly work.

Exactly how it's supposed to. I told the seller as much what stupidity I had done, and he said no worries just ship it back to him. I tried the same test with it and it didn't work (the old gauge), but I think I had killed it days ago trying "experiments" to get it to work.

Now I have an extra egt gauge. Wonder if there's any benefit to putting this in either of my 300 straight sixes...

 

[laserjock]

Happens to the best of us.