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B1395




DTC B018A, B048C, B048F, or B1395

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

* Review Strategy Based Diagnosis Strategy Based Diagnosis for an overview of the diagnostic approach.

* Diagnostic Procedure Instructions Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptors

DTC B018A 02

-
Windshield 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/System Description

The windshield temperature and inside moisture sensor includes the relative humidity sensor, windshield temperature sensor and humidity sensing element temperature sensor.

This sensor assembly provides information about:

* Relative humidity level at windshield inside

* Temperature of the windshield inside

* Temperature of the humidity sensor element

The relative humidity sensor measures the relative humidity of the compartment side of the windshield. It also detects the temperature of the windshield surface on the compartment side. Both values are used as control inputs for the HVAC control module application to calculate the fog risk on windshield 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 windshield. 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 windshield 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 HVAC - Automatic

Connector End View Reference

Component Connector End Views Sunshade - Left (DH6)

Description and Operation

Automatic HVAC Description and Operation HVAC - Automatic

Electrical Information Reference

* Circuit Testing Circuit Testing

* Connector Repairs Connector Repairs

* Testing for Intermittent Conditions and Poor Connections Testing for Intermittent Conditions and Poor Connections

* Wiring Repairs Wiring Repairs

Scan Tool Reference

Control Module References Control Module References for scan tool information

Circuit/System Verification

1. Verify that DTC B1395 03 or B1395 07 is not set.

• If DTC B1395 is set

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

• If DTC B1395 is not set

2. Verify that DTC B048C 02 or B048C 05 is not set.

• If DTC B048C is set

Refer to Humidity Sensor Humidity Circuit Malfunction.

• If DTC B048C is not set

3. Verify that DTC B048F 02 or B048F 05 is not set.

• If DTC B048F is set

Refer to Humidity Sensor Temperature Circuit Malfunction.

• If DTC B048F is not set

4. Verify that DTC B018A 02 or B018A 05 is not set.

• If DTC B018A is set

Refer to Windshield Temperature Sensor Circuit Malfunction.

• If DTC B018A is not set

5. Measure actual temperature using a thermometer at the windshield 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.

• If not within the specified range

Replace the B160 Windshield Temperature and Inside Moisture Sensor.

• If within the specified range

6. Measure actual temperature using a thermometer at the windshield temperature and inside moisture sensor. Compare this value to the scan tool Windshield Temperature parameter. The measured temperature should be within 5°C (9°F) difference of parameter value.

• If not within the specified range

Replace the B160 Windshield Temperature and Inside Moisture Sensor.

• If within the specified range

7. All OK.

Circuit/System Testing

Windshield Temperature and Inside Moisture Sensor Power Supply Malfunction

1. Ignition OFF, disconnect the harness connector at the B160 Windshield Temperature and Inside Moisture Sensor.

2. Test for less than 5 ohms between the ground circuit terminal 3 and ground.

• If 5 ohms or greater

Repair the open/high resistance in the circuit.

• If less than 5 ohms

3. Ignition ON.

4. Test for 4.8-5.2 V between the ground circuit terminal 3 and the 5 V reference voltage circuit terminal 1.

• If less than 4.8 V

1. Ignition OFF, disconnect the X1 harness connector at the K33 HVAC Control Module.

2. Test for infinite resistance between the 5 V reference voltage circuit and ground.

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

• If infinite resistance

3. Test for less than 2 ohms in the 5 V reference voltage circuit end to end.

• If 2 ohms or greater, repair the open/high resistance in the circuit.

• If less than 2 ohms, replace the K33 HVAC Control Module.

• If greater than 5.2 V

1. Ignition OFF, disconnect the X1 harness connector at the K33 HVAC Control Module, ignition ON.

2. Test for less than 0.3 V between the 5 V reference voltage circuit and ground.

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

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

• If within 4.8-5.2 V

5. Replace the B160 Windshield Temperature and Inside Moisture Sensor.

Humidity Sensor Humidity Circuit Malfunction

1. Ignition OFF, disconnect the harness connector at the B160 Windshield Temperature and Inside Moisture Sensor.

2. Test for less than 5 ohms between the ground circuit terminal 3 and ground.

• If 5 ohms or greater

Repair the open/high resistance in the circuit.

• If less than 5 ohms

3. Ignition ON.

4. Test for 4.8-5.2 V between the ground circuit terminal 3 and the 5 V reference voltage circuit terminal 1.

• If less than 4.8 V

1. Ignition OFF, disconnect the X1 harness connector at the K33 HVAC Control Module.

2. Test for infinite resistance between the 5 V reference voltage circuit and ground.

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

• If infinite resistance

3. Test for less than 2 ohms in the 5 V reference voltage circuit end to end.

• If 2 ohms or greater, repair the open/high resistance in the circuit.

• If less than 2 ohms, replace the K33 HVAC Control Module.

• If greater than 5.2 V

1. Ignition OFF, disconnect the X1 harness connector at the K33 HVAC Control Module, ignition ON.

2. Test for less than 0.3 V between the 5 V reference voltage circuit and ground.

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

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

• If within 4.8-5.2 V

5. Test for 4.8-5.2 V between the signal circuit terminal 2 and ground.

• If less than 4.8 V

1. Ignition OFF, disconnect the X1 harness connector at the K33 HVAC Control Module.

2. Test for infinite resistance between the signal circuit and ground.

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

• If infinite resistance

3. Test for less than 2 ohms in the signal circuit end to end.

• If 2 ohms or greater, repair the open/high resistance in the circuit.

• If less than 2 ohms, replace the K33 HVAC Control Module.

• If greater than 5.2 V

1. Ignition OFF, disconnect the X1 harness connector at the K33 HVAC Control Module, ignition ON.

2. Test for less than 0.3 V between the signal circuit and ground.

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

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

• If within 4.8-5.2 V

6. Replace the B160 Windshield Temperature and Inside Moisture Sensor and verify the DTC does not reset.

• If DTC resets

Replace the K33 HVAC Control Module.

• If DTC does not reset

7. All OK.

Humidity Sensor Temperature Circuit Malfunction

1. Ignition OFF, disconnect the harness connector at the B160 Windshield Temperature and Inside Moisture Sensor, ignition ON.

2. Test for 4.8-5.2 V between the signal circuit terminal 5 and ground.

• If less than 4.8 V

1. Ignition OFF, disconnect the X1 harness connector at the K33 HVAC Control Module.

2. Test for infinite resistance between the signal circuit and ground.

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

• If infinite resistance

3. Test for less than 2 ohms in the signal circuit end to end.

• If 2 ohms or greater, repair the open/high resistance in the circuit.

• If less than 2 ohms, replace the K33 HVAC Control Module.

• If greater than 5.2 V

1. Ignition OFF, disconnect the X1 harness connector at the K33 HVAC Control Module, ignition ON.

2. Test for less than 0.3 V between the signal circuit and ground.

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

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

• If within 4.8-5.2 V

3. Replace the B160 Windshield Temperature and Inside Moisture Sensor and verify the DTC does not reset.

• If DTC resets

Replace the K33 HVAC Control Module.

• If DTC does not reset

4. All OK.

Windshield Temperature Sensor Circuit Malfunction

1. Ignition OFF, disconnect the harness connector at the B160 Windshield Temperature and Inside Moisture Sensor, ignition ON.

2. Test for 4.8-5.2 V between the signal circuit terminal 4 and ground.

• If less than 4.8 V

1. Ignition OFF, disconnect the X1 harness connector at the K33 HVAC Control Module.

2. Test for infinite resistance between the signal circuit and ground.

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

• If infinite resistance

3. Test for less than 2 ohms in the signal circuit end to end.

• If 2 ohms or greater, repair the open/high resistance in the circuit.

• If less than 2 ohms, replace the K33 HVAC Control Module.

• If greater than 5.2 V

1. Ignition OFF, disconnect the X1 harness connector at the K33 HVAC Control Module, ignition ON.

2. Test for less than 0.3 V between the signal circuit and ground.

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

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

• If within 4.8-5.2 V

3. Replace the B160 Windshield Temperature and Inside Moisture Sensor and verify the DTC does not reset.

• If DTC resets

Replace the K33 HVAC Control Module.

• If DTC does not reset

4. All OK.

Repair Instructions

Perform the Diagnostic Repair Verification Verification Tests after completing the diagnostic procedure.

Control Module References Control Module References for HVAC control module replacement, programming and setup

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