Analog versus Digital (DIC) Coolant Temp
Tech Contributor
Joined: Oct 1999
Posts: 41,037
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From: Charlotte, NC (formerly Endicott, NY)
I agree. The PCM sends the coolant temperature data to the IP across the Class 2 Serial Bus in digital format where it is displayed directly in the DIC. To show the analog equivalent the digital information (binary ones and zeros) is converted to a voltage and sent to the voltmeter that is calibrated to show temperature (almost all electric analog gauges are voltmeters, just with different calibrations). Due to the errors incurred making the conversion and the quality of the gauge I suspect the accuracy isn't as good. However, no matter what the accuracy is the resolution isn't anywhere near as good so the analog gauge becomes pretty much useless.
Since you are seeing a 10 degree difference between the two you may have an issue with IP grounding or with the 5V reference voltage used by the gauge.
Bill
Since you are seeing a 10 degree difference between the two you may have an issue with IP grounding or with the 5V reference voltage used by the gauge.
Bill
Last edited by Bill Dearborn; Jul 12, 2021 at 01:35 PM.
Thread Starter
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Joined: Aug 2005
Posts: 503
Likes: 50
From: Bradenton, FL
I agree. The PCM sends the coolant temperature data to the IP across the Class 2 Serial Bus in digital format where it is displayed directly in the DIC. To show the analog equivalent the digital information (binary ones and zeros) is converted to a voltage and sent to the voltmeter that is calibrated to show temperature (almost all electric analog gauges are voltmeters, just with different calibrations). Due to the errors incurred making the conversion and the quality of the gauge I suspect the accuracy isn't as good. However, no matter what the accuracy is the resolution isn't anywhere near as good so the analog gauge becomes pretty much useless.
Since you are seeing a 10 degree difference between the two you may have an issue with IP grounding or with the 5V reference voltage used by the gauge.
Bill
Since you are seeing a 10 degree difference between the two you may have an issue with IP grounding or with the 5V reference voltage used by the gauge.
Bill
