A buddy of mine and I spent yesterday installing some guages in his truck, but the pyrometer doesn't seem to be working correctly. I'm stuck as to what's wrong, so hopefully you guys can give me some ideas on what to check.

Gauge is a brand new Autometer Ultralite. Probe is installed pre-turbo. The problem is the needle is very unresponsive. It does move, just very, very slowly. Even from a dead stop, when you floor it, the needle doesn't go over 800 degrees. And, when you stop and let it idle, it takes forever to start to drop.

Any suggestions as to what should be checked. Resistance through the yellow wire, resistance through the thermocouple, connection to gauge power or ground.....???? I'm lost here.

 

a week after install, i had a very similar problem with an ats gauge. had it replaced and the new one acts fine.

 

I remember reading on here about auto meter having some bad gauges. Good luck

 

You could try to swap your guage in his truck to see if that works. If it then works, you know the guage is bad. If your guage in his truck also acts the same as his, then you know his probe is bad or at least a problem w/ wiring. In the end, you WILL know if the guage is the problem!
Good Luck!!

 

Yellow, I thought about that but the power and ground wires on the back of the gauge are hard wired to the gauge, and not removable from the back of the gauge. It would require cutting the power and ground wires on both of our trucks, which I would rather not do to test them.

The more I think about it, the more I'm thinking it's not the gauge, but the thermocouple. When you turn the key on, the needle jumps up, so I think the gauge is working ok and it's acting like it's got power. I guess we need to call Autometer and see if the thermocouple was in the bad batch they had.

 

Jeremy,

I'd bet the farm (that I don't own) that it's the probe. I've had 2 go bad on my Z-series Pyro in the year I've had gauges. Frustrating. 95% certain it's the probe. Try these tests.....Disconnect the probe from the gauge, that's it to get going.....

1. Short the probe posts together, you should read ambient air temp..(ish)

2. Hook a digital volt meter to the positive & negative leads from the probe. Set the meter to mV (millivolts). Get a reading with the truck off and cold. Then fire up the truck and idle, taking readings. Give 'er a little throttle, watching the readings the whole time. The reading should increase with the temp in linear and quick fashion. If you see anything but a steady increase as the exhaust temp rises as well, it's a bad probe(aka thermocouple).

Hope this helps. Give Scott (Cookie88) some rep points sometime, as he was the donor of this troubleshooting method to me....

Kevin

 

Kevin,

Awesome!! That's exactly the kind of info I was looking for. I'm printing your post so we can get the testing done.


Oh, and I tried to leave Scott and you some rep points, but apparently I have to spread some Rep around before I can give it to you guys again.

Edit: On #1, when you say short the probe posts together, do you mean short the red and yellow lead wires from the gauge, disconnected from the probe, and the gauge should read ambient air temp?

 

Disconnect the lead wires at the gauge, and jumper the two posts of the gauge together to read ambient. You will need your 12v applied to the gauge for it to register.

I would agree with Kevin's assessment. It sounds like there might be a case grounding problem within the thermocouple itself. I assume you've already doublechecked all your connections.

 

Did anyone realize that sitting at idle wont get more than 400 degrees? I have to push mine to get anywhere up in the 800 until im driving. Although, ive never sat in the driveway trying to get her up to 800 since im post turbo. Am I wrong?

 

He did say give her a little throttle. It should move even w/out a load.

 

Scott, can I jumper the two lead wires together where they would attach to the thermocouple (but disconnected from the thermocouple) to achieve the same result? It would just be easier to do. But, if the gauge needs to be pulled, that can be done.

Connections are all good, or should be anyway. The thermocouple attaches to the lead wires with a screw and a nut, and the lead wire attaches to the back of the gauge with a nut on the post as well, and I know those are tight - I distinctly remember tightening them.

The only connections I would question are the power and ground connections, but I would think if they are bad the gauge wouldn't work at all.

kennedy, sitting at idle, my truck will reach about 300*, if it idles for a long time and it's really hot out. Typically though, it won't read much above 250-280 until it get's moving. However, on my buddies truck, when we first fired it up, it took some throttle (with the trans in gear and brake applied) to even get it to read 200*. And I think I said it, but from a dead stop accelerating to about 80 MPH, foot to the floor the whole time, it struggles to reach even 800*. Then when you stop and let it idle, it doesn't want to drop below 400*. Granted it's not on a Powerstroke, and it has no chip/tuner, but even stock, the gauge should be reading differently I think.

 

JT, another option is to just leave the thermocouple attached and remove it from the truck. (Well disconnect,remove, and reconnect.) Take a reading with the key on ambient then put it in a pot of boiling water. You know what should happen then.

I'm suspecting a grounding issue with the thermocouple. What vehicle is this thing in?

 

Jeremey - call Autometer direct. 815-899-0801 - yes you will really get someone with a brain. I told the guy I talked to what my gauge was doing (NOT doing), and with NO argument, said "yea somethings wrong" - no BS at all.

I got TWO bad Autometer gauges in a row, right before vacation - I got sick of dealing with it and haven't taken it further yet - but the guy I talked to told me how to test the gauge. He said to call him back, and he would send me a new thermo-couple if the gauge checked out OK


Edit: to test the gauge - he told me to disconnect the probe wires from the back of the gauge, then put power (and ground) to the gauge, and it should read between 0-100* - if so then gauge is ok....

 

It's in a 2004 Cummins. I had absoutley nothing to do with the choice of truck, or you know where I would have directed him. Plus, his work is paying for most of the truck, but it's still his, and they were the ones who basically picked it out for him. Can't argue with someone buying you a truck, even if it's not the first choice.

We'll do some diagnosis of the gauge and thermocouple, using some of the methods suggested here.

Chad, thanks for the number. I have a feeling we'll be calling Autometer for a replacement before this is all said and done.

 

Doesn't matter what truck it's in, still another autometer install situation that we can use info on. Seems to be becoming a trend with that brand.