B1031-EVAPORATOR FIN TEMPERATURE SENSOR CIRCUIT LOW (ATC)
For a complete wiring diagram Refer to Section 8W.
- 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.
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.
Does the scan tool display active: B1031–EVAPORATOR FIN TEMPERATURE SENSOR CIRCUIT LOW?
Yes
- Go To 2
No
- Replace the Evaporator Temperature Sensor in accordance with the Service Information.
- Perform BODY VERIFICATION TEST – VER 1. (Refer to 8 - ELECTRICAL/ELECTRONIC CONTROL MODULES - STANDARD PROCEDURE).
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.
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. (Refer to 8 - ELECTRICAL/ELECTRONIC CONTROL MODULES - STANDARD PROCEDURE).
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.
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. (Refer to 8 - ELECTRICAL/ELECTRONIC CONTROL MODULES - STANDARD PROCEDURE).
No
- Replace the A/C Heater Control in accordance with the Service Information.
- Perform BODY VERIFICATION TEST – VER 1. (Refer to 8 - ELECTRICAL/ELECTRONIC CONTROL MODULES - STANDARD PROCEDURE).