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DTC B018A, B048C, B048F, or B1395

Diagnostic Instructions
    • Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
    • Review Strategy Based Diagnosis for an overview of the diagnostic approach.
    • Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptors

DTC B018A 02: Windscreen Temperature Sensor Circuit Short to Ground

DTC B018A 05: Windshield Temperature Sensor Circuit High Voltage/Open

DTC B048C 02: Humidity Sensor Humidity Circuit Short to Ground

DTC B048C 05: Humidity Sensor Humidity Circuit High Voltage/Open

DTC B048F 02: Humidity Sensor Temperature Circuit Short to Ground

DTC B048F 05: Humidity Sensor Temperature Circuit High Voltage/Open

DTC B1395 03: Control Module Voltage Reference Output Circuit Low Voltage

DTC B1395 07: Control Module Voltage Reference Output Circuit High Voltage

Diagnostic Fault Information

Circuit

Short to Ground

Open/High Resistance

Short to Voltage

Signal Performance

Windshield Temperature and Inside Moisture Sensor 5V Reference

B1395 03

B1395 03

B1395 07

-

Humidity Signal

B048C 02

B048C 05

B048C 05

-

Humidity Temperature Signal

B048F 02

B048F 05

B048F 05

-

Windscreen Temperature Signal

B018A 02

B018A 05

B018A 05

-

Windscreen Temperature and Inside Moisture Sensor Ground

-

B018A 05, B048C 05, B048F 05, B1395 03

--

--

Circuit/System Description

The windscreen temperature and inside moisture sensor integrates the relative humidity sensor, windscreen temperature sensor and humidity sensing element temperature sensor.

This sensor assembly provides information about:

    • Relative humidity level on inside windscreen
    • Temperature of the inside windscreen
    • Temperature of the humidity sensor element

The relative humidity sensor measures the relative humidity on the compartment side of the windscreen. It also detects the temperature of the windscreen surface on the compartment side. Both values are used as control inputs for the HVAC control module application to calculate the fog risk on windscreen compartment side and ability to reduce fuel consumption by decreasing A/C compressor power to a minimum without causing any fog. The sensor will also enable partial recirculation mode in order to improve heat-up performance of the passenger compartment under cold ambient temperature conditions without the risk of mist build-up on the windscreen. The humidity sensor element temperature sensor supplies the temperature of the humidity sensor element. It is only needed if the thermal contact between the humidity sensing element and the inside windscreen surface is not sufficient.

Conditions for Running the DTC
    • Ignition ON
    •  The HVAC control module is ON.

Conditions for Setting the DTC

B018A 02, B048C 02, B048C 02 or B1395 03

The HVAC control module detects the sensor signal out of range. The signal voltage is less than 0.1 V for more than 50 ms.

B018A 05, B048C 05, B048C 05 or B1395 07

The HVAC control module detects the sensor signal out of range. The signal voltage is greater than 4.9 V for more than 50 ms.

Action Taken When the DTC Sets
    • The system will use the last valid values as default.
    • If no value is read at the time of fault, the HVAC control module uses 60% for humidity.

Conditions for Clearing the DTC

The condition for setting the DTC is no longer present.

Reference Information

Schematic Reference

HVAC Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Automatic HVAC Description and Operation

Electrical Information Reference

    •  Circuit Testing
    •  Connector Repairs
    •  Testing for Intermittent Conditions and Poor Connections
    •  Wiring Repairs

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification
  1. Verify that DTC B1395 03 or B1395 07 is not present.
    2. [ARW-LISTFAIL]

  2. If DTC B1395 is present

    Refer to Windscreen Temperature And Inside Moisture Sensor Power Supply Malfunction.

    3. [/ARW-LISTFAIL][ARW-LISTPASS]

  3. If DTC B1395 is not present

    4. [/ARW-LISTPASS]
  4. Verify that DTC B048C 02 or B048C 05 is not present.
    5. [ARW-LISTFAIL]

  5. If DTC B048C is present

    Refer to Humidity Sensor Humidity Circuit Malfunction.

    6. [/ARW-LISTFAIL][ARW-LISTPASS]

  6. If DTC B048C is not present

    7. [/ARW-LISTPASS]
  7. Verify that DTC B048F 02 or B048F 05 is not present.
    8. [ARW-LISTFAIL]

  8. If DTC B048F is present

    Refer to Humidity Sensor Temperature Circuit Malfunction.

    9. [/ARW-LISTFAIL][ARW-LISTPASS]

  9. If DTC B048F is not present

    10. [/ARW-LISTPASS]
  10. Verify that DTC B018A 02 or B018A 05 is not present.
    11. [ARW-LISTFAIL]

  11. If DTC B018A is present

    Refer to Windscreen Temperature Sensor Circuit Malfunction.

    12. [/ARW-LISTFAIL][ARW-LISTPASS]

  12. If DTC B018A is not present

    13. [/ARW-LISTPASS]
  13. Measure actual temperature using a thermometer at the windscreen temperature and inside moisture sensor. Compare this value to the scan tool Passenger Compartment Humidity Sensor Temperature parameter. The measured temperature should be within 5°C (9°F) difference of parameter value.
    14. [ARW-LISTFAIL]

  14. If not within the specified range

    Replace the B160 Windscreen Temperature and Inside Moisture Sensor.

    15. [/ARW-LISTFAIL][ARW-LISTPASS]

  15. If within the specified range

    16. [/ARW-LISTPASS]
  16. Measure actual temperature using a thermometer at the windscreen temperature and inside moisture sensor. Compare this value to the scan tool Windscreen Temperature parameter. The measured temperature should be within 5°C (9°F) difference of parameter value.
    17. [ARW-LISTFAIL]

  17. If not within the specified range

    Replace the B160 Windscreen Temperature and Inside Moisture Sensor.

    18. [/ARW-LISTFAIL][ARW-LISTPASS]

  18. If within the specified range

    19. [/ARW-LISTPASS]
  19. All OK.

Circuit/System Testing

Windscreen Temperature And Inside Moisture Sensor Power Supply Malfunction

  1. Ignition OFF, disconnect the harness connector at the B160 Windscreen Temperature and Inside Moisture Sensor.
  2. Test for less than 5 Ω between the ground circuit terminal 3 and ground.
    3. [ARW-LISTFAIL]

  3. If greater than 5 Ω

    Repair the open/high resistance in the circuit.

    4. [/ARW-LISTFAIL][ARW-LISTPASS]

  4. If less than 5 Ω

    5. [/ARW-LISTPASS]
  5. Ignition ON, test for 4.8-5.2 V between the ground circuit terminal 3 and the reference voltage circuit terminal 1.
    6. [ARW-LISTFAIL]

  6. If less than 4.8 V

    7. [/ARW-LISTFAIL]
    3.1. Ignition OFF, disconnect the X1 harness connector at the K33 HVAC Control Module.
    3.2. Test for infinite resistance between the reference voltage circuit and ground.
    [ARW-LISTFAIL]

  7. If less than infinite resistance, repair the short to ground on the circuit.

    8. [/ARW-LISTFAIL][ARW-LISTPASS]

  8. If infinite resistance

    9. [/ARW-LISTPASS]
    3.3. Test for less than 2 Ω in the reference voltage circuit end to end.
    [ARW-LISTFAIL]

  9. If 2 Ω or greater, repair the open/high resistance in the circuit.

  10. If less than 2 Ω, replace the K33 HVAC Control Module.

    11. [/ARW-LISTFAIL] [ARW-LISTFAIL]

  11. If greater than 5.2 V

    12. [/ARW-LISTFAIL]
    3.1. Ignition OFF, disconnect the X1 harness connector at the K33 HVAC Control Module.
    3.2. Ignition ON, test for less than 0.3 V between the reference voltage circuit and ground.
    [ARW-LISTFAIL]

  12. If greater than 0.3 V, repair the short to voltage on the circuit.

  13. If less than 0.3 V, replace the K33 HVAC Control Module.

    14. [/ARW-LISTFAIL] [ARW-LISTPASS]

  14. If within 4.8-5.2 V

    15. [/ARW-LISTPASS]
  15. Replace the B160 Windscreen Temperature and Inside Moisture Sensor.

Humidity Sensor Humidity Circuit Malfunction

  1. Ignition OFF, disconnect the harness connector at the B160 Windscreen Temperature and Inside Moisture Sensor.
  2. Test for less than 5 Ω between the ground circuit terminal 3 and ground.
    3. [ARW-LISTFAIL]

  3. If greater than 5 Ω

    Repair the open/high resistance in the circuit.

    4. [/ARW-LISTFAIL][ARW-LISTPASS]

  4. If less than 5 Ω

    5. [/ARW-LISTPASS]
  5. Ignition ON, test for 4.8-5.2 V between the ground circuit terminal 3 and the reference voltage circuit terminal 1.
    6. [ARW-LISTFAIL]

  6. If less than 4.8 V

    7. [/ARW-LISTFAIL]
    3.1. Ignition OFF, disconnect the X1 harness connector at the K33 HVAC Control Module.
    3.2. Test for infinite resistance between the reference voltage circuit and ground.
    [ARW-LISTFAIL]

  7. If less than infinite resistance, repair the short to ground on the circuit.

    8. [/ARW-LISTFAIL][ARW-LISTPASS]

  8. If infinite resistance

    9. [/ARW-LISTPASS]
    3.3. Test for less than 2 Ω in the reference voltage circuit end to end.
    [ARW-LISTFAIL]

  9. If 2 Ω or greater, repair the open/high resistance in the circuit.

  10. If less than 2 Ω, replace the K33 HVAC Control Module.

    11. [/ARW-LISTFAIL] [ARW-LISTFAIL]

  11. If greater than 5.2 V

    12. [/ARW-LISTFAIL]
    3.1. Ignition OFF, disconnect the X1 harness connector at the K33 HVAC Control Module.
    3.2. Ignition ON, test for less than 0.3 V between the reference voltage circuit and ground.
    [ARW-LISTFAIL]

  12. If greater than 0.3 V, repair the short to voltage on the circuit.

  13. If less than 0.3 V, replace the K33 HVAC Control Module.

    14. [/ARW-LISTFAIL] [ARW-LISTPASS]

  14. If within 4.8-5.2 V

    15. [/ARW-LISTPASS]
  15. Test for 4.8-5.2 V between the signal circuit terminal 2 and ground.
    16. [ARW-LISTFAIL]

  16. If less than 4.8 V

    17. [/ARW-LISTFAIL]
    4.1. Ignition OFF, disconnect the X1 harness connector at the K33 HVAC Control Module.
    4.2. Test for infinite resistance between the signal circuit and ground.
    [ARW-LISTFAIL]

  17. If less than infinite resistance, repair the short to ground on the circuit.

    18. [/ARW-LISTFAIL][ARW-LISTPASS]

  18. If infinite resistance

    19. [/ARW-LISTPASS]
    4.3. Test for less than 2 Ω in the signal circuit end to end.
    [ARW-LISTFAIL]

  19. If 2 Ω or greater, repair the open/high resistance in the circuit.

  20. If less than 2 Ω, replace the K33 HVAC Control Module.

    21. [/ARW-LISTFAIL] [ARW-LISTFAIL]

  21. If greater than 5.2 V

    22. [/ARW-LISTFAIL]
    4.1. Ignition OFF, disconnect the X1 harness connector at the K33 HVAC Control Module.
    4.2. Ignition ON, test for less than 0.3 V between the signal circuit and ground.
    [ARW-LISTFAIL]

  22. If greater than 0.3 V, repair the short to voltage on the circuit.

  23. If less than 0.3 V, replace the K33 HVAC Control Module.

    24. [/ARW-LISTFAIL] [ARW-LISTPASS]

  24. If within 4.8-5.2 V

    25. [/ARW-LISTPASS]
  25. Replace the B160 Windscreen Temperature and Inside Moisture Sensor and verify the DTC does not reset.
    26. [ARW-LISTFAIL]

  26. If DTC resets

    Replace the K33 HVAC Control Module.

    27. [/ARW-LISTFAIL][ARW-LISTPASS]

  27. If DTC does not reset

    28. [/ARW-LISTPASS]
  28. All OK.

Humidity Sensor Temperature Circuit Malfunction

  1. Ignition OFF, disconnect the harness connector at the B160 Windscreen Temperature and Inside Moisture Sensor.
  2. Ignition On, test for 4.8-5.2 V between the signal circuit terminal 5 and ground.
    3. [ARW-LISTFAIL]

  3. If less than 4.8 V

    4. [/ARW-LISTFAIL]
    2.1. Ignition OFF, disconnect the X1 harness connector at the K33 HVAC Control Module.
    2.2. Test for infinite resistance between the signal circuit and ground.
    [ARW-LISTFAIL]

  4. If less than infinite resistance, repair the short to ground on the circuit.

    5. [/ARW-LISTFAIL][ARW-LISTPASS]

  5. If infinite resistance

    6. [/ARW-LISTPASS]
    2.3. Test for less than 2 Ω in the signal circuit end to end.
    [ARW-LISTFAIL]

  6. If 2 Ω or greater, repair the open/high resistance in the circuit.

  7. If less than 2 Ω, replace the K33 HVAC Control Module.

    8. [/ARW-LISTFAIL] [ARW-LISTFAIL]

  8. If greater than 5.2 V

    9. [/ARW-LISTFAIL]
    2.1. Ignition OFF, disconnect the X1 harness connector at the K33 HVAC Control Module.
    2.2. Ignition ON, test for less than 0.3 V between the signal circuit and ground.
    [ARW-LISTFAIL]

  9. If greater than 0.3 V, repair the short to voltage on the circuit.

  10. If less than 0.3 V, replace the K33 HVAC Control Module.

    11. [/ARW-LISTFAIL] [ARW-LISTPASS]

  11. If within 4.8-5.2 V

    12. [/ARW-LISTPASS]
  12. Replace the B160 Windscreen Temperature and Inside Moisture Sensor and verify the DTC does not reset.
    13. [ARW-LISTFAIL]

  13. If DTC resets

    Replace the K33 HVAC Control Module.

    14. [/ARW-LISTFAIL][ARW-LISTPASS]

  14. If DTC does not reset

    15. [/ARW-LISTPASS]
  15. All OK.

Windscreen Temperature Sensor Circuit Malfunction

  1. Ignition OFF, disconnect the harness connector at the B160 Windscreen Temperature and Inside Moisture Sensor.
  2. Ignition On, test for 4.8-5.2 V between the signal circuit terminal 4 and ground.
    3. [ARW-LISTFAIL]

  3. If less than 4.8 V

    4. [/ARW-LISTFAIL]
    2.1. Ignition OFF, disconnect the X1 harness connector at the K33 HVAC Control Module.
    2.2. Test for infinite resistance between the signal circuit and ground.
    [ARW-LISTFAIL]

  4. If less than infinite resistance, repair the short to ground on the circuit.

    5. [/ARW-LISTFAIL][ARW-LISTPASS]

  5. If infinite resistance

    6. [/ARW-LISTPASS]
    2.3. Test for less than 2 Ω in the signal circuit end to end.
    [ARW-LISTFAIL]

  6. If 2 Ω or greater, repair the open/high resistance in the circuit.

  7. If less than 2 Ω, replace the K33 HVAC Control Module.

    8. [/ARW-LISTFAIL] [ARW-LISTFAIL]

  8. If greater than 5.2 V

    9. [/ARW-LISTFAIL]
    2.1. Ignition OFF, disconnect the X1 harness connector at the K33 HVAC Control Module.
    2.2. Ignition ON, test for less than 0.3 V between the signal circuit and ground.
    [ARW-LISTFAIL]

  9. If greater than 0.3 V, repair the short to voltage on the circuit.

  10. If less than 0.3 V, replace the K33 HVAC Control Module.

    11. [/ARW-LISTFAIL] [ARW-LISTPASS]

  11. If within 4.8-5.2 V

    12. [/ARW-LISTPASS]
  12. Replace the B160 Windscreen Temperature and Inside Moisture Sensor and verify the DTC does not reset.
    13. [ARW-LISTFAIL]

  13. If DTC resets

    Replace the K33 HVAC Control Module.

    14. [/ARW-LISTFAIL][ARW-LISTPASS]

  14. If DTC does not reset

    15. [/ARW-LISTPASS]
  15. All OK.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Inside Air Moisture and Windscreen Temperature Sensor Replacement
    • Control Module References for HVAC control module replacement, setup, and programming
   


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