mrfred

iTrader: (50)

Does anyone have a link to a page or document that shows the GM IAT sensor volts vs temperature scaling?

mrfred

iTrader: (50)

I'm mostly finding that the data on these sensors is presented as resistance vs temperature. In looking at how these temperature sensors work, I'm getting the impression that the sensor run in series with a resistor inside the ECU, and so we need to know the resistance of the resistor in the ECU to get the voltage. Is that correct?

GrocMax

You need to calculate the voltage divider with 5v thru a pullup inside the ECU, and the resistance/temp chart of the sensor.

mrfred

iTrader: (50)

Thanks. I've got the spreadsheet done. Just need to figure out the value of the internal resistor in the ECU for the fuel temperature circuit. I don't imagine that anyone has determined the value of that internal resistor?

l2r99gst

iTrader: (2)

I can try to look it up in the FSM if you want, to see if it is listed.

The Innovate Logworks manual has a method listed to find the load resistor values for thermistor sensors used by ECUs. You can download the manual from the Innovate website. It is section 10.2 of the LogWorks 2 manual.

I think I PMd you the V to temp for the GM IAT sensor. That was for a load resistor of 2.2 Kohms with a 5V supply.

EDIT: Didn't realize the FSM didn't list the resistor values. Guess you have to do it the hard way.


Eric

mrfred

iTrader: (50)

Its done. Turns out the resistor is 2.2-2.3 Kohms. :-) MAT logging via the ECU coming soon.