Manual Three Zone Temperature Control

B1031-Evaporator Temperature Sensor Circuit Low

For a complete wiring diagram, refer to.

• When Monitored: Continuously with the ignition on.

• Set Condition: The Evaporator Temperature Sensor voltage input to the A/C Heater Control is equal to or below 0.01 of a volt for a continuous period of five seconds. If the A/C Heater Control detects a valid voltage, the Diagnostic Trouble Code (DTC) will change from active to stored and will stay stored for 100 ignition cycles.






Always perform the HVAC Pre-Diagnostic Troubleshooting procedure before proceeding. Refer to => Non-DTC Based
Diagnostics. HVAC Pre-Diagnostic Troubleshooting Procedure

Test Step 1 - CHECK IF THE DTC IS ACTIVE

• Ignition on, engine not running.

• With the scan tool, read HVAC DTCs.

Is this DTC active?

Yes

• Go to Test Step 2 => [ Test Step 2 - CHECK (C21) EVAPORATOR TEMPERATURE SENSOR SIGNAL CIRCUIT
FOR A SHORT TO GROUND ]

No

• Go to Test Step 5 => [ Test Step 5 - CHECK THE WIRING AND CONNECTORS ]

Test Step 2 - CHECK (C21) EVAPORATOR TEMPERATURE SENSOR SIGNAL CIRCUIT FOR A SHORT TO GROUND







• Turn the ignition off to the lock position.

• Disconnect the A/C Heater Control C1 harness connector.

• Disconnect the Evaporator Temperature Sensor harness connector.

• Measure the resistance between ground and the (C21) Evaporator Temperature Sensor Signal circuit.

Is the resistance below 100k Ohms?

Yes

• Repair the (C21) Evaporator Temperature Sensor Signal circuit for a short to ground.

• Perform the HVAC Verification Test. Refer to => Non-DTC Based Diagnostics. HVAC Verification Test

No

• Go to Test Step 3 => [ Test Step 3 - CHECK (C21) EVAPORATOR TEMPERATURE SENSOR SIGNAL CIRCUIT
FOR A SHORT TO THE (C121) SENSOR GROUND CIRCUIT ]

Test Step 3 - CHECK (C21) EVAPORATOR TEMPERATURE SENSOR SIGNAL CIRCUIT FOR A SHORT TO THE (C121) SENSOR GROUND CIRCUIT







• Measure the resistance between the (C21) Evaporator Temperature Sensor Signal circuit and the (C121) Sensor Ground circuit.

Is the resistance below 100k Ohms?

Yes

• Repair the (C21) Evaporator Temperature Sensor Signal circuit for a short to (C121) Sensor Ground circuit.

• Perform the HVAC Verification Test. Refer to => Non-DTC Based Diagnostics. HVAC Verification Test

No

• Go to Test Step 4 => [ Test Step 4 - CHECK THE EVAPORATOR TEMPERATURE SENSOR ]

Test Step 4 - CHECK THE EVAPORATOR TEMPERATURE SENSOR

• Replace the Evaporator Temperature Sensor.

• With the scan tool, erase HVAC DTCs and cycle the ignition off for 30 seconds then back on.

• Using the scan tool read HVAC DTCs.

Does this DTC reset?

Yes

• Replace and program the A/C Heater Control.

• Perform the HVAC Verification Test. Refer to => Non-DTC Based Diagnostics. HVAC Verification Test

No

• Test complete.

• Perform the HVAC Verification Test. Refer to => Non-DTC Based Diagnostics. HVAC Verification Test

Test Step 5 - CHECK THE WIRING AND CONNECTORS

• The conditions necessary to set the DTC are not present at this time.

• Using the scan tool, check the Environmental Data to help identify the conditions in which the DTC was set.

• Using the wiring diagrams as a guide, check all related splices and connectors for signs of water intrusion, corrosion, pushed out or bent terminals, and correct pin tension.

• Wiggle the wiring and connectors while checking for shorted and open circuits.

Were there any problems found?

Yes

• Repair as necessary.

• Perform the HVAC Verification Test. Refer to => Non-DTC Based Diagnostics. HVAC Verification Test

No

• Test complete.