Evaporator Temperature Sensor Failure

NOTE: After making any repairs, perform BODY VERIFICATION TEST under VERIFICATION TESTS.

Monitored & Set Condition

When Monitored: With the ignition on.
Set Condition: The BCM detects an abnormally high or low voltage on the evaporator temperature sensor signal.

Possible Causes:

Evaporator Temperature Sensor Signal CKT Short To Voltage
Evaporator Temperature Sensor Open
Evaporator Temp Sensor Signal CKT Open
Sensor Ground Open
Body Control Module - Evaporator Temp Sensor Stays High
Evaporator Temperature Sensor - Code Returns
Evaporator Temperature Sensor - Code With A/C Operating
Evaporator Temp Sensor Signal Circuit Short To Ground
Evaporator Temp Sensor Signal CKT Short To Sensor Ground
Body Control Module - Evaporator Sensor Stays Low

Testing

Turn the ignition on. With the scan tool in SENSORS, read the evaporator temperature sensor voltage. If the scan tool displays EVAP TEMP: 5.2 VOLTS or more, go to next step. If not, go to step 6 .
Turn ignition off. Disconnect the evaporator temperature sensor harness connector. See Figure . Turn ignition on. Measure the voltage of the evaporator temperature sensor signal circuit. If the voltage is 5.3 volts or more, repair the evaporator temperature sensor signal circuit. If the voltage is 5.3 volts or less, go to next step.
Connect a jumper wire between the evaporator temperature sensor signal circuit and the sensor ground circuit. With the scan tool in SENSORS, read the evaporator temperature sensor voltage. If the scan tool displays EVAP TEMP: 4.9 VOLTS or more, go to next step. If not, replace the evaporator temperature sensor. See EVAPORATOR TEMPERATURE SENSOR under REMOVAL & INSTALLATION.
Turn ignition off. Disconnect the BCM C2 harness connector. See Figure . Measure the resistance of the evaporator temperature sensor signal circuit between the BCM C2 connector and the evaporator temperature sensor connector. If the resistance is 5 ohms or less, go to next step. If the resistance is 5 ohms or more, repair the evaporator temperature sensor signal circuit for an open.
Disconnect the BCM C1 harness connector. See Figure . Measure the resistance of the sensor ground circuit between the BCM C1 connector and the evaporator temperature sensor connector. If the resistance is 5 ohms or less, replace the BCM. See BODY CONTROL MODULE under REMOVAL & INSTALLATION. If the resistance is 5 ohms or more, repair the sensor ground circuit for an open.
Disconnect the evaporator temperature sensor harness connector. See Figure . Turn ignition on. With the scan tool in SENSORS, read the evaporator temperature sensor voltage. If the scan tool displays EVAP TEMP: 4.9 VOLTS or more, go to next step. If no, go to step 9 .
Reconnect the evaporator temperature sensor. Turn ignition off. With the scan tool, read BODY COMPUTER DTC's. Turn ignition on. Wait 2 minutes. With the scan tool, read BODY COMPUTER DTC's. If the scan tool displays, EVAPORATOR TEMPERATURE SENSOR FAILURE, replace the evaporator temperature sensor. If no, go to next step.
Start engine. Turn the A/C system on and run for at least 5 minutes, so water will form on the evaporator temperature sensor. With the scan tool, read the BODY COMPUTER DTC's. If the scan tool displays, EVAPORATOR TEMPERATURE SENSOR FAILURE, replace the evaporator temperature sensor. If no, the evaporator temperature sensor should be fully operational.
Turn ignition off. Disconnect evaporator temperature sensor harness connector. Disconnect the BCM C2 harness connector. See Figure . Measure the resistance between ground and the evaporator temperature sensor signal circuit at the BCM C2 connector. If the resistance is 1000 ohms or less, repair the evaporator temperature sensor signal circuit for a short to ground. If the resistance is 1000 ohms or more, go to next step.
Disconnect the BCM C1 harness connector. See Figure . Measure the resistance between the evaporator temperature sensor signal circuit and the sensor ground circuit in the evaporator temperature sensor connector. If the resistance is 1000 ohms or less, repair the evaporator temperature sensor signal circuit for a short to the sensor ground circuit. If the resistance is 1000 ohms or more, replace the BCM. See BODY CONTROL MODULE under REMOVAL & INSTALLATION.