Does anyone have any specific information about the cat temperature probe used in the 60 series trucks? Is it a Thermocouple, RTD or Thermistor? What are it's characteristics (output vs temperature). Thanks for any leads.
Catalytic converter temperature probe (2 Viewers)
- Thread starter Engineer8000
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Based on the schematic in the emissions manual, it looks like some kind of resistance device. I thought there was some test procedure where you heat it up and confirm the circuit closes (like a switch), but I don't see it in the manual.
It's a Thermistor. Not much info on that part, other than it's used to prevent overheating of the CAT. More important for the old, OE giant brick CAT. Not really an issue with the new, high-flow designs.
It controls the Air Injection (via Emissions Computer), through On/Off of the VSV for the AI system.
It controls the Air Injection (via Emissions Computer), through On/Off of the VSV for the AI system.
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- #4
Thanks for the info guys. I was looking for the resistance at 785 C where it tells the computer to turn off the AI. I guess I could reverse engineer it with a known good emissions computer.
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- #5
I'm guessing it looks something like this:
If NTC thermistor, temp sensor resistance decreases as temperature increases, so Vs would decrease as temperature increases.
If NTC thermistor, temp sensor resistance decreases as temperature increases, so Vs would decrease as temperature increases.
Yes... And it's not very scientific or precise, but I test those Thermosensors buy hooking up a multimeter and hitting the tip with a heat gun and see if the Ohms go under 10. I don't know what the threshold is to trigger the VSV.
