I'm fighting a similar battle. 411 PCM with ls7 card-style maf. I downloaded the spreadsheet and entered the data into my IAT Calibration table -- reads about -37 all the time. What am I missing?
I'm fighting a similar battle. 411 PCM with ls7 card-style maf. I downloaded the spreadsheet and entered the data into my IAT Calibration table -- reads about -37 all the time. What am I missing?
If your IAT is reading -37 the wiring is probably incorrect. Scoob had the same issue. You heed to check thatOriginally Posted by Kesamot
1997 30th SS. Torqhead 24x, TFS heads, 223/235 cam, 4l80e, S60 D1SC 14psi
So can we just re-pin the Gen 3 harness to plug into the card MAF? otherwise I'm looking at the ITC billet harness
https://www.amazon.com/gp/product/B0...I4LHV0ZX&psc=1
Also, I'm not clear on where the pullup resister goes in? Can anyone explain that?
Could you go into a little more detail on the resistor wiring?
Going to restart this... I ask well am doing this swap and am getting -37 at all times.
I have all the itc adapter fittings and the wiring appears to have the proper flow
screenshot.23-02-2023 14.37.44.png
Unplug the MAF/IAT. You should have some voltage (could be +5v, or +12v, or (rarely) something else altogether, it depends on the subsystem) on one of the IAT pins, and ground on the other IAT pin. If you don't, find out why. I'd go direct to the PCM to ignore all the wiring and breakout harnesses and randon Amazon garbage that tends to get installed, and backprobe the PCM connector directly to check for that.
With the IAT unplugged, voltage at the signal tap inside the PCM will be equal to whatever the supply rail is, since there is no current flow (no path to GND with the IAT unplugged). The IAT signal/IAT value displayed should be at its max: high voltage = low temp, for this circuit.
That means the reverse is also true: low voltage = high temp. Short the two IAT pins together and the circuit will be pulled down to ground. Everything after the internal pull-up resistor should be very close to GND or zero V, and that's why the signal tap is located where it is.
If you can't make it go high (low temp) by unplugging, and then go low (high temp) by shorting, your wiring is wrong. Or the PCM is fried. But you can't call the PCM bad until you know for sure that the wiring is correct.
Put on your blinders and ignore everything but this:
screenshot.23-02-2023 15.09.20.png
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