Test X: The Outside Air Temperature Display Is Inoperative/Inaccurate

PINPOINT TEST X: THE OUTSIDE AIR TEMPERATURE DISPLAY IS INOPERATIVE/INACCURATE

X1-X4:

X4-X5:

X6:

Normal Operation
The outside air temperature sensor is mounted on the radiator core support in front of the radiator and A/C condenser and is hardwired to the instrument cluster through input circuit 767 (LB/OG) and return circuit 242 (DG). The instrument cluster provides a reference voltage to the ambient air temperature sensor and monitors the change in voltage resulting from changes in resistance as determined by outside air temperature. When the engine has been off or the engine temperature is cold, the instrument cluster displays the current outside air temperature as measured by the ambient air temperature sensor. When the engine is not cold, the instrument cluster takes a reading of the current temperature and compares the current reading against the last reading at key off. If the temperature is less than the last key off temperature reading, the instrument cluster displays the current temperature. If the temperature is greater than the last key off temperature reading, the instrument cluster displays the last key off temperature reading until the ambient air temperature has had time to stabilize with vehicle movement.

NOTE: On vehicles equipped with electronic automatic temperature control (EATC), the climate control assembly displays the outside air temperature. The instrument cluster only displays the outside air temperature on vehicles that are not equipped with EATC.

DTC B1255 - is a continuous and on-demand DTC that sets if the instrument cluster detects an open on the outside air temperature sensor input circuit 767 (LB/OG). If the instrument cluster detects an open on the outside air temperature input, the instrument cluster defaults the display to dashes (------).

DTC B1257 - is a continuous and on-demand DTC that sets if the instrument cluster detects a short to ground on the outside air temperature sensor input circuit 767 (LB/OG). If the instrument cluster detects a short to ground on the outside air temperature input, the instrument cluster defaults the display to dashes (------).

Possible Causes
- Circuit 242 (DG) open or short to ground
- Circuit 767 (LB/OG) open or short to ground
- Outside air temperature sensor
- Instrument cluster