Temperature Indicator
02-17-2015, 12:21 PM
#2
Deceased
Join Date: 06-30-2010
Location: Kannapolis NC
Posts: 25,739
From a technical question response by GuitHHR, dating way back to 2006...
"Outside Air Temperature:
The outside air temperature is read by the body control module (BCM) and transmitted over serial data to the instrument panel cluster (IPC) for display in the driver information center (DIC). The BCM provides the logic for reading the outside air temperature sensor. The BCM sends the temperature to the IPC in Celsius. The IPC is responsible for displaying the temperature and converting to Fahrenheit.
The sensor operates within a temperature range of -40°C to +60°C (-40°F to +140°F). The ambient air temperature sensor is mounted in the forward engine area, behind the left front headlamp. This causes an air flow issue due to the sensor's location and can effect the ambient air update display parameter in the DIC of the vehicle. For model year 2008 the ambient air temperature sensor will have a new location closer to the grill airflow. In the present position, it is exposed to limited airflow from the grill before it reaches the radiator. The sensor signal varies between 0-5 volts.
The ambient air temperature sensor algorithm uses 3 pieces of information, outside air temperature data, vehicle speed, and time the engine was turned off.
The ambient air temperature is updated and displayed by the DIC under the following conditions....
If the current ambient air temperature value is cooler than or equal to the old temperature value. Vehicle speed is in excess of 33 mph.
Displays outside actual temperature. Display updates every second.
If the current ambient air temperature value is warmer than the old temperature value. Vehicle speed is less than or drops below 18 mph.
Displays last temperature recorded during last ignition cycle. No update.
New ambient temperature exceeds the previous ignition cycle recorded ambient temperature, and vehicle speed exceeds 18 mph but is less than 33 mph.
Displays outside actual temperature. Display will be updated at a slow rate.
Vehicle speed is greater than or equal to 45 mph. (for at least 3 minutes)
Displays outside actual temperature Display updates at a quicker rate."
Hope this helps, sluggish/sticking temp displays have been a topic of discussion here for ages.
"Outside Air Temperature:
The outside air temperature is read by the body control module (BCM) and transmitted over serial data to the instrument panel cluster (IPC) for display in the driver information center (DIC). The BCM provides the logic for reading the outside air temperature sensor. The BCM sends the temperature to the IPC in Celsius. The IPC is responsible for displaying the temperature and converting to Fahrenheit.
The sensor operates within a temperature range of -40°C to +60°C (-40°F to +140°F). The ambient air temperature sensor is mounted in the forward engine area, behind the left front headlamp. This causes an air flow issue due to the sensor's location and can effect the ambient air update display parameter in the DIC of the vehicle. For model year 2008 the ambient air temperature sensor will have a new location closer to the grill airflow. In the present position, it is exposed to limited airflow from the grill before it reaches the radiator. The sensor signal varies between 0-5 volts.
The ambient air temperature sensor algorithm uses 3 pieces of information, outside air temperature data, vehicle speed, and time the engine was turned off.
The ambient air temperature is updated and displayed by the DIC under the following conditions....
If the current ambient air temperature value is cooler than or equal to the old temperature value. Vehicle speed is in excess of 33 mph.
Displays outside actual temperature. Display updates every second.
If the current ambient air temperature value is warmer than the old temperature value. Vehicle speed is less than or drops below 18 mph.
Displays last temperature recorded during last ignition cycle. No update.
New ambient temperature exceeds the previous ignition cycle recorded ambient temperature, and vehicle speed exceeds 18 mph but is less than 33 mph.
Displays outside actual temperature. Display will be updated at a slow rate.
Vehicle speed is greater than or equal to 45 mph. (for at least 3 minutes)
Displays outside actual temperature Display updates at a quicker rate."
Hope this helps, sluggish/sticking temp displays have been a topic of discussion here for ages.
02-27-2015, 11:59 PM
#7
Senior Member
Join Date: 04-14-2010
Location: Wisconsin
Posts: 432
I have a 95 Blazer that the external temperature is very accurate in but the one in my newer 2006 HHR has always been erratic. The dealer just gave me the GM party line on how the system works and I need to get the vehicle up to speed. I leave the garage on a below zero morning and drive at 50 mph most of the 10 mile trip unless I get stopped at a traffic light. The outside temperature will read the 45 degree garage temperature all the way to work. My Blazer changes as soon as I open the garage door. I did the same thing at the dealership. I had the service manager take a ride with me. We left the heated service lane, drove a 7 mile loop on the highway at 65mph and the temperature didn't change. They replaced the sensor and it was the same way. It almost has to be a software problem.
You can buy a $5 thermometer to stick on your outside mirror that works much better and there are several electronic ones under $30 that have a clock and a freezing weather audio alert.
You can buy a $5 thermometer to stick on your outside mirror that works much better and there are several electronic ones under $30 that have a clock and a freezing weather audio alert.
