ISSPRO Pyro Problem

[alpo]

Anyone have trouble with their ISSPRO EGT gauge? Mine quit working...checked power to the signal box, all wires intact, only 18 months old. Anyone know how to isolate the defective component down to the thermocouple, box, or gauge?

Thanks,
Alpo

[40grit]

If you have a multimeter( fluke, etc) that has a Ohm scale, lift the leads and check the leads to the thermocouple, it should have some value when sitting at ambient temp, change the temp by running the truck for a few minutes, check again, it should have changed. If it shows a low ohm (short in the wiring) or stays wide open (high due to open circuit) resistance wise it would be a thermocouple problem. It depends on the actual thermocouple used as to what the values you see will be, but they should change when you change temp at the probe.

If you knew the range of the probe used, you could hook up different resistors to the box ( from radioshack or such)and should get different temp readings according to the curve of the thermocouple used...

[janderson]

Thermocouples put out a given voltage for a certain temperature( mv range). This can be measured with the fluke meter and is high enough at the temperatures involved. Warm it up and watch the voltage readings get larger to confirm thermocouple operation.

[linchhummmer]

make sure that the wires on the thermocouple dont touch or it will short it out and you will have to put a new porbe in it just tape them so they dont tuch ive had a few that have gone out

[Subzilla]

I know you said you checked the wires to the box but that seems to be a very troubling spot on my Isspro guages. The smaller diameter wires plus the screw-in connections have vibrated loose multiple times on mine (pyro & trans temp on both my 6.2's) plus one of my trans temp guages has a loose connection in the box that I can's seem to fix. It is in the wiring as I can move it around and get the needle to flucuate. The "goo" they put on these connections at the factory doesn't seem to help hold the screw in place. Not happy with the wiring, obviously.

Let us know what you find.

[linchhummmer]

why dont you just cut them and splice them together

[cowboywildbill]

From what I have read. If you cut and splice or solder or even use crimp connectors, it may change the resistance of the wires and give you a false reading. They actually make the wires certain lengths to match resistance. I needed longer wires for one of our trucks for an overhead gauge and the manufacturer sent me one's that were 4' longer.
They said the wires had to be in certain increments of length to be accurate.
So I had an extra 2' of wire but it read correctly.

[GordonMarks]

For what it's worth:
We've handled ISSPRO for about 20 yrs. & they have a very good tech dept. I've been using them on my vehicles since 80. Everytime I've had trouble, it's always been the connections between the leadwire where it hooks to the thermocouple or a broken leadwire-operator error I guess. I've been guilty of changing the thermocouple a couple of times(or more)only to find that the problem occurs again in a few days.
I'm curious: what is the "little black box" that is referred to a couple of times? Turbotemp monitor?
my $.0003 worth.

[Subzilla]

Gordon Marks! Good to see the A/C guy on the forums. Haven't heard from you in a while!

The black box seems to be the brains of the system that you hide out of sight. The sensor and power wires lead into this box and out goes the light and signal wires to the guage.