PIT4211D

Bulletin No.: PIT4211D
Date: Feb-2016
Subject:
Ambient Temperature Display Not Reading Outside Temperature at Times or A/C Compressor Inoperative
Due To Low Ambient Temperature
Models:
2008-2016 Buick Enclave
2009-2016 Chevrolet Traverse
2007-2016 GMC Acadia
2007-2010 Saturn Outlook
2007-2014 Cadillac Escalade Models
2007-2013 Chevrolet Avalanche, Silverado
2007-2014 Chevrolet Silverado 2500/3500, Suburban, Tahoe
2007-2013 GMC Sierra
2007-2014 GMC Sierra 2500/3500, Yukon Models
This PI was superseded to update the Models section. Please discard PIT4211C.
The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.
Condition/Concern
The outside air temperature display utilizes a very specific filtering routine of the ambient temperature sensor signal so the display will update gradually without
making large jumps in the reading and to eliminate the possibility of erratic readings under certain driving conditions.
A number of important functional characteristics that may be helpful in determining if the system is functioning properly.
The temperature display is always allowed to update quickly when the ambient temperature is getting colder while driving, but the display takes much longer to
update when the temperature is getting warmer.
This prevents false updates to the temperature display while driving in slow or stop and go traffic in hot weather.
The temperature display will always read the actual ambient temperature when the vehicle is started if the temperature has dropped since the last key cycle. It
will not update to the actual ambient temperature if it is warmer since the last key cycle unless the key has been off for at least 2.5 hours.
If a customer has a concern with the function or accuracy of the outside air temperature display, perform the instant update to determine if the display will read
the accurate temperature. If the instant update creates an accurate reading, do not replace the ambient temperature sensor.
Explain to the customer that the system is designed to filter the ambient temperature sensor reading to prevent erratic readings in temperature.
Additionally, when diagnosing an HVAC system concern, some technicians may find that the A/C compressor will not engage because the ambient temperature
is too low as determined by the Ambient Temperature Sensor.
The A/C compressor is disabled in temperatures below 2 degrees Celsius (36 degrees Fahrenheit). Typically this will occur when the vehicle is parked outside
in temperatures below 2 degrees Celsius (36 degrees Fahrenheit) and then brought into the shop.
Since the ambient temperature does not update instantly, it will be necessary to perform an instant update of the ambient temperature sensor in order to
proceed with diagnostics.
Recommendation/Instructions
To perform an Instant Update of the Ambient Temperature Sensor, Press and hold the Recirc button and A/C button on the HVAC Control Head simultaneously.
1
It is also possible to perform this by using a scan tool in special function mode and select instant OST update.
Within a few seconds, the DIC should display the current temperature.
Additional SI Keywords
intermittent
Please follow this diagnostic or repair process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the
remaining steps do not need to be performed.
GM bulletins are intended for use by professional technicians, NOT a "do-it-yourselfer". They are written to inform these technicians of conditions that may
occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools,
safety instructions, and know-how to do a job properly and safely. If a condition is described, DO NOT assume that the bulletin applies to your vehicle, or that
your vehicle will have that condition. See your GM dealer for information on whether your vehicle may benefit from the information.
WE SUPPORT VOLUNTARY TECHNICIAN CERTIFICATION
2

Bulletin No.: PIT4211D
Date: Feb-2016
Subject:
Ambient Temperature Display Not Reading Outside Temperature at Times or A/C Compressor Inoperative
Due To Low Ambient Temperature
Models:
2008-2016 Buick Enclave
2009-2016 Chevrolet Traverse
2007-2016 GMC Acadia
2007-2010 Saturn Outlook
2007-2014 Cadillac Escalade Models
2007-2013 Chevrolet Avalanche, Silverado
2007-2014 Chevrolet Silverado 2500/3500, Suburban, Tahoe
2007-2013 GMC Sierra
2007-2014 GMC Sierra 2500/3500, Yukon Models
This PI was superseded to update the Models section. Please discard PIT4211C.
The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.
Condition/Concern
The outside air temperature display utilizes a very specific filtering routine of the ambient temperature sensor signal so the display will update gradually without
making large jumps in the reading and to eliminate the possibility of erratic readings under certain driving conditions.
A number of important functional characteristics that may be helpful in determining if the system is functioning properly.
The temperature display is always allowed to update quickly when the ambient temperature is getting colder while driving, but the display takes much longer to
update when the temperature is getting warmer.
This prevents false updates to the temperature display while driving in slow or stop and go traffic in hot weather.
The temperature display will always read the actual ambient temperature when the vehicle is started if the temperature has dropped since the last key cycle. It
will not update to the actual ambient temperature if it is warmer since the last key cycle unless the key has been off for at least 2.5 hours.
If a customer has a concern with the function or accuracy of the outside air temperature display, perform the instant update to determine if the display will read
the accurate temperature. If the instant update creates an accurate reading, do not replace the ambient temperature sensor.
Explain to the customer that the system is designed to filter the ambient temperature sensor reading to prevent erratic readings in temperature.
Additionally, when diagnosing an HVAC system concern, some technicians may find that the A/C compressor will not engage because the ambient temperature
is too low as determined by the Ambient Temperature Sensor.
The A/C compressor is disabled in temperatures below 2 degrees Celsius (36 degrees Fahrenheit). Typically this will occur when the vehicle is parked outside
in temperatures below 2 degrees Celsius (36 degrees Fahrenheit) and then brought into the shop.
Since the ambient temperature does not update instantly, it will be necessary to perform an instant update of the ambient temperature sensor in order to
proceed with diagnostics.
Recommendation/Instructions
To perform an Instant Update of the Ambient Temperature Sensor, Press and hold the Recirc button and A/C button on the HVAC Control Head simultaneously.
1
It is also possible to perform this by using a scan tool in special function mode and select instant OST update.
Within a few seconds, the DIC should display the current temperature.
Additional SI Keywords
intermittent
Please follow this diagnostic or repair process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the
remaining steps do not need to be performed.
GM bulletins are intended for use by professional technicians, NOT a "do-it-yourselfer". They are written to inform these technicians of conditions that may
occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools,
safety instructions, and know-how to do a job properly and safely. If a condition is described, DO NOT assume that the bulletin applies to your vehicle, or that
your vehicle will have that condition. See your GM dealer for information on whether your vehicle may benefit from the information.
WE SUPPORT VOLUNTARY TECHNICIAN CERTIFICATION
2