Pinpoint Test AI: The Outside Air Temperature Display Does Not Operate Correctly
Instrumentation, Message Center and Warning Chimes
Pinpoint Tests
Pinpoint Test AI: The Outside Air Temperature Display Does Not Operate Correctly
Refer to Wiring Diagram Set 60, Instrument Cluster for schematic and connector information. Diagrams By Number
Normal Operation
The ambient 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 (IC) through the input and return circuits. The IC 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 for 2 hours, or the engine temperature is cold, the IC displays the current outside air temperature as measured by the ambient air temperature sensor. When the time is less than 2 hours, or if the engine is not cold, the IC 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 IC displays the current temperature. If the temperature is greater than the last key off temperature reading, the IC displays the last key off temperature reading until the outside air temperature has had time to stabilize with vehicle movement of greater than 30 km/h (19.6 mph) for approximately 20 seconds.
- DTC B1255 (Air Temperature External Sensor Circuit Open) - a continuous and on-demand DTC that sets if the IC detects an open on the ambient air temperature sensor input circuit. If the IC detects an open on the outside air temperature input, the IC defaults the display to 23.89°C (75°F).
- DTC B1257 (Air Temperature External Sensor Circuit Short to Ground) - a continuous and on-demand DTC that sets if the IC detects a short to ground on the ambient air temperature sensor input circuit. If the IC detects a short to ground on the outside air temperature input, the IC defaults the display to 23.89°C (75°F).
This pinpoint test is intended to diagnose the following:
- Wiring, terminals or connectors
- Ambient air temperature sensor
- IC
PINPOINT TEST AI: THE OUTSIDE AIR TEMPERATURE DISPLAY DOES NOT OPERATE CORRECTLY
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 IC SELF-TEST
- Check for recorded IC DTCs from the self-test.
- Is IC DTC B1255 or DTC B1257 recorded?
Yes
GO to AI4.
No
VERIFY that the vehicle has been driven to eliminate any potential heat soak condition and cool off the sensor.
If the outside air temperature display is still inaccurate, GO to AI2.
-------------------------------------------------
AI2 VERIFY THE SPEEDOMETER OPERATION
- Operate the vehicle and verify the speedometer operation.
- Does the speedometer operate correctly?
Yes
GO to AI3.
No
GO to Pinpoint Test F. Pinpoint Test F: The Speedometer Is Inoperative
-------------------------------------------------
AI3 CHECK THE AMBIENT AIR TEMPERATURE SENSOR FUNCTION
- Ignition OFF.
- Disconnect: Ambient Air Temperature Sensor C132 .
- Measure the resistance between the ambient air temperature sensor C132 pin 1, component side and the ambient air temperature sensor C132 pin 2, component side according to the following table.
- Does the ambient air temperature sensor resistance match the ambient air temperature according to the table?
Yes
The system is operating normally at this time. Explain to the customer the normal operation of the system.
No
INSTALL a new ambient air temperature sensor. REFER to Climate Control Ambient Air Temperature Sensor. TEST the system for normal operation.
-------------------------------------------------
AI4 CLEAR THE DTCs AND RECHECK THE SYSTEM
- Clear the DTCs and repeat the IC self-test.
- Is IC DTC B1255 or DTC B1257 recorded?
Yes
GO to AI5.
No
The system is operating normally at this time.
-------------------------------------------------
AI5 CHECK THE AMBIENT AIR TEMPERATURE SENSOR FUNCTION
- Ignition OFF.
- Disconnect: Ambient Air Temperature Sensor C132 .
- Ignition ON.
- Measure the voltage between the ambient air temperature sensor C132-1, circuit RH111 (GY/BU), harness side and the ambient air temperature sensor C132-2, circuit VH407 (YE/GN), harness side.
- Is the voltage approximately 5 volts?
Yes
INSTALL a new ambient air temperature sensor. REFER to Climate Control Ambient Air Temperature Sensor. CLEAR the DTCs. REPEAT the self-test.
No
GO to AI6.
-------------------------------------------------
AI6 CHECK THE OUTSIDE AIR TEMPERATURE SENSOR INPUT AND RETURN CIRCUITS FOR A SHORT TO VOLTAGE
- Ignition OFF.
- Disconnect: IC C220 .
- Ignition ON.
- Measure the voltage between the IC C220-22, circuit VH407 (YE/GN), harness side and ground; and between the IC C220-20, circuit VMC29 (YE), harness side and ground.
- Is any voltage present?
Yes
REPAIR the circuit in question. REPEAT the self-test. CLEAR the DTCs.
No
GO to AI7.
-------------------------------------------------
AI7 CHECK THE OUTSIDE AIR TEMPERATURE INPUT CIRCUIT FOR AN OPEN AND SHORT TO GROUND
- Ignition OFF.
- Measure the resistance between the IC C220-22, circuit VH407 (YE/GN), harness side and the ambient air temperature sensor C132-2, circuit VH407 (YE/GN), harness side; and between the IC C220-22, circuit VH407 (YE/GN), harness side and ground.
- Is the resistance less than 5 ohms between the IC and the ambient air temperature sensor, and greater than 10,000 ohms between the IC and ground?
Yes
GO to AI8.
No
REPAIR circuit VH407 (YE/GN) for an open or for a short to ground. TEST the system for normal operation.
-------------------------------------------------
AI8 CHECK THE OUTSIDE AIR TEMPERATURE RETURN CIRCUIT FOR AN OPEN
- Measure the resistance between the IC C220-20, circuit VMC29 (YE), harness side and the ambient air temperature sensor C132-1, circuit RH111 (GY/BU), harness side.
- Is the resistance less than 5 ohms?
Yes
GO to AI9.
No
REPAIR circuit RH111 (GY/BU) for an open. CLEAR the DTCs. REPEAT the self-test.
-------------------------------------------------
AI9 CHECK FOR CORRECT IC OPERATION
- Disconnect all the IC connectors.
- Check for:
- corrosion
- damaged pins
- pushed-out pins
- Connect all the IC connectors and make sure they seat correctly.
- Operate the system and verify the concern is still present.
- Is the concern still present?
Yes
INSTALL a new IC. REFER to Instrument Cluster (IC) Instrument Cluster (IC). TEST the system for normal operation.
No
The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector.
-------------------------------------------------