B1031

B1031-EVAPORATOR FIN TEMPERATURE SENSOR CIRCUIT LOW (ATC)

B1031 - Evaporator Fin Temperature Sensor Circuit Low (ATC):

WHEN MONITORED
With the ignition on.

SET CONDITION
If the Evaporator Temperature Sensor input is out of range toward the low voltage threshold.

POSSIBLE CAUSES
- (C21) evaporator temperature sensor signal circuit shorted to ground
- (C21) evaporator temperature sensor signal circuit shorted to (c121) sensor ground circuit
- Evaporator temperature sensor
- A/C heater control

NOTE: This DTC must be active for the results of this test to be valid. Do not perform this test if this DTC is stored. Refer to HVAC System Test (ATC) for stored DTC test procedures. HVAC System Test (ATC)

Diagnostic Test




1. CHECK FOR DTC B1031-EVAPORATOR FIN TEMPERATURE SENSOR CIRCUIT LOW WITH EVAPORATOR TEMPERATURE SENSOR HARNESS CONNECTOR DISCONNECTED

Turn the ignition off.
Disconnect the Evaporator Temperature Sensor harness connector.
Turn the ignition on.
With the scan tool, erase HVAC DTCs.
Turn the ignition off, wait 10 seconds, and then turn the ignition on.
With the scan tool, read HVAC DTCs.

Q: Does the scan tool display active: B1031-EVAPORATOR FIN TEMPERATURE SENSOR CIRCUIT LOW?

YES: Go To 2
NO: Replace the Evaporator Temperature Sensor. Perform BODY VERIFICATION TEST - VER 1. Body Verification Test




2. CHECK (C21) EVAPORATOR TEMPERATURE SENSOR SIGNAL CIRCUIT FOR A SHORT TO GROUND

Turn the ignition off.
Disconnect the A/C Heater Control C2 harness connector.
Measure the resistance of the (C21) Evaporator Temperature Sensor Signal circuit between ground and the A/C Heater Control C2 harness connector.

Q: Is the resistance below 10k ohms?

YES: Repair the (C21) Evaporator Temperature Sensor Signal circuit for a short to ground. Perform BODY VERIFICATION TEST - VER 1. Body Verification Test
NO: Go To 3




3. CHECK (C21) EVAPORATOR TEMPERATURE SENSOR SIGNAL CIRCUIT FOR A SHORT TO (C121) SENSOR GROUND CIRCUIT

Measure the resistance between the (C21) Evaporator Temperature Sensor Signal circuit and the (C121) Sensor Ground circuit in the A/C Heater Control C2 harness connector.

Q: Is the resistance below 10k ohms?

YES: Repair the (C21) Evaporator Temperature Sensor Signal circuit for a short to the (C121) Sensor Ground circuit. Perform BODY VERIFICATION TEST - VER 1. Body Verification Test
NO: Replace the A/C Heater Control. Perform BODY VERIFICATION TEST - VER 1. Body Verification Test