ATC

B1031-EVAPORATOR FIN TEMPERATURE SENSOR CIRCUIT LOW (ATC)





For a complete wiring diagram Consult Diagrams/Electrical.

- When Monitored:
With the ignition on.

- Set Condition:
If the Evaporator Temperature Sensor input is out of range toward the low voltage threshold, (A/D counts reach low threshold of 16). This DTC has a maturing time of 5 seconds and a de-maturing time of 10 seconds. If the DTC's status changes from active to stored it will stay in memory for 100 ignition cycles.





NOTE: DTC B1031 must be active for the results of this test to be valid. Do not perform this test if DTC B1031 is stored. Refer to HVAC System Test (ATC) for stored DTC test procedures.HVAC System Test

Diagnostic Test

1. CHECK FOR DTC B1031-EVAPORATOR FIN TEMPERATURE SENSOR CIRCUIT LOW WITH IN-LINE C202 HARNESS CONNECTOR DISCONNECTED




Turn the ignition off.
Disconnect the in-line C202 harness connector.
Turn the ignition on.
With the scan tool, erase HVAC DTCs.
Turn the ignition off, wait 10 seconds, and turn the ignition on.
With the scan tool, read HVAC DTCs.
Does the scan tool display: B1031-EVAPORATOR FIN TEMPERATURE SENSOR CIRCUIT LOW?

Yes

- Go To 2

No

- Go To 4

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 between the A/C Heater Control C2 harness connector and the in-line C202 (IP SIDE) harness connector.
- 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




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 between the A/C Heater Control C2 harness connector and the in-line C202 (IP SIDE) harness connector.
- 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.

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




Turn the ignition off.
Disconnect the Evaporator Temperature Sensor harness connector.
Measure the resistance of the (C21) Evaporator Temperature Sensor Signal circuit between ground and the Evaporator Temperature Sensor harness connector.
Is the resistance below 10k ohms?

Yes

- Repair the (C21) Evaporator Temperature Sensor Signal circuit for a short to ground between the Evaporator Temperature Sensor harness connector and the in-line C202 (HVAC SIDE) harness connector.
- Perform BODY VERIFICATION TEST - VER 1. Body Verification Test.

No

- Go To 5

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




Measure the resistance between the (C21) Evaporator Temperature Sensor Signal circuit and the (C121) Sensor Ground circuit in the Evaporator Temperature Sensor 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 between the Evaporator Temperature Sensor harness connector and the in-line C202 (HVAC SIDE) harness connector.
- Perform BODY VERIFICATION TEST - VER 1. Body Verification Test.

No

- Replace the Evaporator Temperature Sensor.
- Perform BODY VERIFICATION TEST - VER 1. Body Verification Test.