Pinpoint Test AI: The Outside Air Temperature Display Is Inoperative/Incorrect

Instrumentation, Message Center and Warning Chimes

Pinpoint Test AI: The Outside Air Temperature Display Is Inoperative/Incorrect


Normal Operation

The outside air temperature is displayed in the Front Display Interface Module (FDIM). The Ambient Air Temperature (AAT) sensor is hardwired to the PCM through separate input and return circuits. The PCM provides a reference voltage to the AAT (Ambient Air Temperature) sensor and monitors the change in voltage resulting from changes in resistance as determined by outside air temperature. The PCM then messages the ambient air temperature data to the HVAC module through the Body Control Module (BCM) over the High Speed Controller Area Network (HS-CAN). The BCM (Body Control Module) then filters the temperature data and sends the updated temperature status to the FDIM (Front Display Interface Module) over the Medium Speed Controller Area Network (MS-CAN).

The HVAC module is programmed to update the messaged outside temperature data at different rates depending on several criteria to prevent false temperature displays due to a condition known as heat soaking. Heat soaking is where the outside air temperature is hotter in the location of the AAT (Ambient Air Temperature) sensor than the actual outside air temperature.

When the sensed outside temperature rises, the display updates slowly at varying rates based on vehicle speed. When the sensed outside temperature drops, the display updates more quickly following the drop experienced by the AAT (Ambient Air Temperature) sensor.

This pinpoint test is intended to diagnose the following:

- Communication concern

- PCM concern

PINPOINT TEST AI : THE OUTSIDE AIR TEMPERATURE DISPLAY IS INOPERATIVE/INCORRECT

NOTICE: Use the correct probe adapter(s) when making measurements. Failure to use the correct probe adapter(s) may damage the connector.

AI1 RETRIEVE THE RECORDED DTCs FROM THE FDIM (Front Display Interface Module) SELF-TEST

- Check for recorded FDIM (Front Display Interface Module) DTCs from the self-test.

Are any DTCs recorded?

Yes
For DTC U0164, REFER to Accessories and Optional Equipment.
No
GO to AI2.

AI2 RETRIEVE THE RECORDED DTCs FROM THE HVAC MODULE SELF-TEST

- Check for recorded HVAC module DTCs from the self-test.

Are any DTCs recorded?

Yes
REFER to Heating and Air Conditioning.
No
GO to AI3.

AI3 RETRIEVE THE RECORDED DTCs FROM THE PCM KOEO (Key ON Engine OFF) SELF-TEST

- Check for recorded PCM DTCs from the Key ON Engine OFF (KOEO) self-test.

Are any ambient temperature sensor DTCs recorded?

Yes
REFER to Computers and Control Systems. TEST the system for normal operation.
No
The system is operating correctly at this time. The condition may have been caused by a heat soak concern.