Ambient Air Temperature Display/Sensor Inaccurate During PDI
| Subject: | Ambient Air Temperature Display/Sensor Inaccurate During PDI |
| Models: | 2008-2009 Buick Allure (Canada Only), LaCrosse |
| 2008-2009 Chevrolet Impala |
| 2008 Pontiac Grand Prix |
This bulletin is being revised to add the 2009 model year. Please discard Corporate Bulletin Number 08-01-39-003 (Section 01 - HVAC).
Technicians may notice that the ambient temperature display is inaccurate during PDI.
The ambient temperature sensor uses an algorithm that delays updating the display unless certain conditions are met, such as driving the vehicle at a certain speed. This ensures that the sensor does not detect engine heat when the vehicle is idling, which would result in an inaccurate temperature reading.
Important: DO NOT replace the ambient temperature display or sensor.
Technicians are to ensure that the ambient temperature display has updated using information from the tables below. It is recommended that the vehicle be driven to update the display.
Important: If one of the methods below are used to update the temperature instantly, the temperature sensor may detect engine heat resulting in artificially high reading.
Condition | Display |
|---|---|
At start up with the engine OFF for less than 3 hours | Displays last stored temperature unless temperature has decreased. The temperature reading is always instantly updated if the ambient air temperature has decreased |
At start up with the engine OFF for more than 3 hours | Displays actual outside temperature |
Vehicle moving over 10 mph (16 km/h) for 5 minutes | Updates temperature display at a slow, filtered rate |
Vehicle moving at or above 32 mph (51 km/h) for 2.5 minutes | Updates temperature display rapidly |
When the HVAC module, A/C and recirculation buttons are pressed simultaneously | Updates temperature display instantly |
When the ambient air decreases | Updates temperature display rapidly |
Condition | Display |
|---|---|
At start up with the engine OFF for less than 3 hours | Displays last stored temperature |
At start up with the engine OFF for more than 3 hours | Displays actual outside temperature |
Vehicle moving over 10 mph (16 km/h) for 5 minutes | Updates temperature display at a slow, filtered rate |
Vehicle moving at or above 32 mph (51 km/h) for 2.5 minutes | Updates temperature display as rapidly as possible |
When the sensor reading is less than displayed value | Updates temperature display as rapidly as possible |
When the front defrost, rear defroster and fan up buttons are pressed simultaneously | Updates temperature display instantly |
