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GM IAT not reading: 04 MSM, Rev MS2E

Old 03-04-2017, 08:21 PM
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Xio
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Question GM IAT not reading: 04 MSM, Rev MS2E

I am slowly working on install and tuning of a Reverant MS2E in my 04 MSM, and I am having issues with the GM IAT sensor. I've wired the GM IAT into the wires for the stock pre-throttle body sensor (IAT2), and setup the GM sensor in Calibrate Thermistors per instructions, but it reads a constant 80 degrees F in Tunerstudio, regardless of actual temperature.

Everything else with the install has gone well so far. ID725's, TPS, base timing, startup, idle tuning, even some Autotune at low speeds in the neighborhood... all good.

To troubleshoot the problem, I've performed these actions:
- wired in the old stock sensor. It too reads a constant value, regardless of settings in Calibrate Thermistor or actual temperature.
- used a heat gun to try and get either sensor to respond. No dice.
- measured voltage across the wires (with either sensor in place and key on), and from each wire to an engine bay ground... all measurements read basically zero (some noise up to 0.15V)
- checked continuity on both wires (from engine bay back to the pin in the connector that plugs into the ECU, pins 4O and 4R)... both read 0.3-0.5 ohms, so should be good?

It appears to me that I am not getting a signal to the IAT at all. Are there other tests I should perform? Could this be an issue with the ECU?

Other thoughts:
- I did move the harness where the IAT2 wires are (a bit) when I installed the ID725's. However, I don't think I moved it enough to break a wire...
- The IAT2 ground (black/red) is a shared with several other sensors (CLT for example). All these sensors function correctly in TS.

All help is appreciated, as I am fairly certain I need this sensor to function in TS if I wanna get this car running right.
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Old 03-19-2017, 04:42 PM
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Bump. Anyone?
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Old 03-19-2017, 08:17 PM
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Looks like you need a pull up resistor to 5v, 2.49k Ohm I believe. You can add this in the wiring loom or preferably in the ECM case, quite a few input channels have a spot on the board to add the pull up resistor.
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Old 06-06-2017, 01:08 PM
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you ever get any resolve to this?? I have the same issue
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Old 06-06-2017, 11:17 PM
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Originally Posted by ReallyRottenTurbo View Post
you ever get any resolve to this?? I have the same issue
Yes, got it sorted after contacting Reverant. I'll reply in your thread.
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