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sdeeter19555

Calibrate the outside temperature sensor?

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Anyone know how to calibrate the outside temperature sensor? Ours is about 10 degrees off...it was nearly 50 degrees and it was registering 40.

 

Steve

2012 2500hd 6.0l

 

 

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Try pressing the AC and Recirc buttons at the same time.  That has been the behind-the-scenes 'instant update' fix on the outside temp sensors for GM vehicles for many years now.  

 

It seems the General has the computer programmed to always let the sensor temp go down, but never to go up unless a list of factors are met (such as driving at highway speeds) to prevent underhood heat from causing an erroneous reading (go figure).  

 

On my truck, a lot of the time, especially this time of year, the temp reading will get stuck at a cold morning temp (say like 32F) and then if it gets 60 in the afternoon, if I am just driving short trips around town, it will not let the Auto HVAC work correctly until I do one of those 'instant resets'.  

Edited by MaverickZ71

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Quote

The scan tool has the ability to update the displayed ambient air temperature. To update the ambient air temperature display on the HVAC control module, perform the following procedure: Turn ON the ignition. Simultaneously press the A/C and Recirc switches for 5 seconds.

 

Edited by newdude

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Perfect, I will give that a try. This is the wife's Equinox...can't even remember what the dash layout is.

Steve
2012 2500hd 6.0l

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On ‎12‎/‎21‎/‎2017 at 1:52 PM, sdeeter19555 said:

Perfect, I will give that a try. This is the wife's Equinox...can't even remember what the dash layout is.

Steve
2012 2500hd 6.0l
 

 

That may change things...however that procedure might work still.  What year Equinox is it? 

Edited by newdude

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That may change things...however that procedure might work still.  What year Equinox is it? 
2017, right before they redesigned...

Steve
2012 2500hd 6.0l

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The reset procedure "could" work and might still be worth a try...

 

Looking at the Equinox however, the outside temp sensor has no..."direct" relation to the HVAC control module. 

 

Quote

 

Outside Air Temperature

The outside air temperature can be accessed through the driver information center Trip/Fuel switch function. The driver information center shows the outside air temperature as a damped value. The time and rate of the temperature update is based on an algorithm in the instrument cluster. Factors such as last temperature reading, current temperature reading, length of time the vehicle was off, current vehicle speed, and the distance driven effect when the displayed temperature is updated. To get the vehicle to display the most accurate temperature faster, drive the vehicle. Constant moving traffic will update the display to the correct temperature more quickly than stop and go traffic.

 

The instrument cluster monitors the ambient air temperature sensor with a low reference circuit and 5 V signal circuit. The instrument cluster monitors the voltage drop across the sensor, which is proportional to temperature. When the ambient air temperatures are cold, the resistance of the sensor is high and the voltage signals are high. When the ambient air temperatures are hot, the resistance of the sensors is low and the voltage signals are low. The instrument cluster converts the voltage value to a temperature value of Celsius or Fahrenheit that will be displayed by the display.

 

 

I would not rule out a faulty sensor or poor terminal tension (worst case bad cluster) because of its setup.  Even looking at the schematics for the HVAC and then the sensor itself, the only schematic the sensor shows up in is the Instrument Cluster schematic.  From the IPC, the IPC sends the information to the ECM and then to the HVAC, so HVAC is just getting the information on temperature from other modules.  Its a green/white signal wire and yellow 5v reference wire that make up the plug for it, and they trace right to the IPC. 

Edited by newdude

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