Buick Regal: DTC B0163, B0183, or B1405

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 B0163

Passenger Compartment Temperature Sensor Circuit

DTC B0183

Solar Load Sensor Circuit

DTC B1405

Control Module Voltage Reference Output 2 Circuit

For symptom byte information, refer to Symptom Byte List.

Diagnostic Fault Information

Circuit/System Description

The ambient light/sunload sensor integrates the sunload and passenger compartment temperature functions within a single assembly.

The solar sensor uses 4 unique circuits as detailed below:

• Low reference circuit - This is a common ground for the ambient light/sunload sensor assembly.
• Temperature signal circuit - This is the signal circuit for the temperature sensor.
• Clock signal circuit - This has 2 functions, via a high side PWM signal, the HVAC control module supplies power to the sensor as well as a clock input for the sensor microprocessor.
• Sunload signal circuit - This is used as an output from the solar sensor to the HVAC control module to transmit sun heat (IR) intensity, elevation, and azimuth data.

The sunload sensor is connected to ground and to a clocked power supply through the HVAC control module. This clocked power supply is to power the sensor electronics and to work as a clock generator to the sunload sensor micro controller. The sensor uses a pulse signal for data identification and transferring the sun intensity measurement. At each positive transition from the clocked supply input, the sunload sensor micro controller will shift channels enabling new intensity measurement on the signal output to the HVAC control module. The signal voltage varies between 0 - 5 V.

The passenger compartment temperature sensor is a negative temperature coefficient thermistor. As the air temperature increases, the sensor resistance decreases. The sensor signal varies between 0 - 5 V.

Bright or high intensity light causes the vehicles interior temperature to increase. The automatic HVAC system compensates for the increased temperature by diverting additional cool air into the vehicle.

Conditions for Running the DTC

• Ignition ON
• The HVAC control module is ON.

Conditions for Setting the DTC

B0163 02

The input signal is out of range. The HVAC control module detects voltage less than 0.1 V on the temperature signal circuit.

B0163 05

The input signal is out of range. The HVAC control module detects voltage greater than 4.9 V on the temperature signal circuit.

B0183 02

The input signal is out of range. The HVAC control module detects voltage less than 0.1 V on the solar sensor signal circuit.

B0183 05

The input signal is out of range. The HVAC control module detects voltage greater than 4.9 V on the solar sensor signal circuit.

B1405 02

Clocked supply for multi zone sensor is shorted to ground.

B1405 05

Clocked supply for multi zone sensor is shorted to voltage or open.

Action Taken When the DTC Sets

B0163 02, B0163 05, B0183 02, B0183 05

The system will use the last valid values as a default.

B1405 02, B1405 05

If no value is read at the time of fault, the HVAC control module uses 0 W/m2 as intensity.

Conditions for Clearing the DTC

The condition for setting the DTC is no longer present.

Reference Information

Schematic Reference

HVAC Wiring Schematics

Connector End View Reference

Component Connector End View Index

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 B1405 02 or B1405 05 is not set.

• If DTC B1405 is set

Refer to Voltage Reference Malfunction.

• Go to next step: If DTC B1405 is not set

2. Verify the actual inside air temperature, using a thermometer, is less than a 3ºC (5ºF) difference from the scan tool Inside Passenger Compartment Air Temp. Sensor parameter

• If greater than a 3ºC (5ºF) difference

Refer to Sensor Circuit Malfunction

• Go to next step: If less than a 3ºC (5ºF) difference

3. Verify the scan tool Sunload parameter changes while covering the B10B Ambient Light/Sunload Sensor with a shop towel and changes when shining a bright light on it

• If the Sunload parameter does not change

Refer to Sensor Circuit Malfunction

• Go to next step: If the Sunload parameter changes

4. All OK.

Circuit/System Testing

Voltage Reference Malfunction

1. Ignition OFF and all vehicle systems OFF, disconnect the harness connector at the B10B Ambient Light/Sunload Sensor. It may take up to 10 min for all vehicle systems to power down.

NOTE: The scan tool must be disconnected from the vehicle before performing the next test.

2. Test for less than 10 Ω between the low reference circuit terminal 6 and ground.

• If 10 Ω or greater

1. Ignition OFF, disconnect the harness connector at the K33 HVAC Control Module.
2. Test for less than 2 Ω in the low reference circuit end to end.
   • If 2 Ω or greater, repair the open/high resistance in the circuit.
   • If less than 2 Ω, replace the K33 HVAC Control Module.

• Go to next step: If less than 10 Ω

3. Disconnect the X1 harness connector at the

4. Test for less than 0.3 V between the B10B Ambient Light/Sunload Sensor reference voltage circuit terminal 2 and ground.

• If greater than 0.3 V

Repair the short to voltage on the circuit.

• Go to next step: If less than 0.3 V

5. Ignition OFF.

6. Test for infinite resistance between the B10B Ambient Light/Sunload Sensor reference voltage circuit terminal 2 and ground.

• If less than infinite resistance

Repair the short to ground on the circuit.

• Go to next step: If infinite resistance

7. Test for less than 5 Ω between the B10B Ambient Light/Sunload Sensor reference voltage circuit terminal 2 and control circuit terminal 20 X1 at the K33 HVAC Control Module harness connector.

• If 5 Ω or greater

Repair the open/high resistance in the circuit.

• Go to next step: If less than 5 Ω

8. Replace the B10B Ambient Light/Sunload Sensor and verify the DTC does not reset.

• If DTC resets

Replace the K33 HVAC Control Module.

• Go to next step: If DTC does not reset

9. All OK.

Sensor Circuit Malfunction

1. Ignition OFF and all vehicle systems OFF, disconnect the harness connector at the B10B Ambient Light/Sunload Sensor. It may take up to 10 min for all vehicle systems to power down.

NOTE: The scan tool must be disconnected from the vehicle before performing the next test.

2. Test for less than 10 Ω between the low reference circuit terminal 6 and ground.

• If 10 Ω or greater

1. Ignition OFF, disconnect the harness connector at the K33 HVAC Control Module.
2. Test for less than 2 Ω in the low reference circuit end to end.
   • If 2 Ω or greater, repair the open/high resistance in the circuit.
   • If less than 2 Ω, replace the K33 HVAC Control Module.

• Go to next step: If less than 10 Ω

3. Ignition ON, test for 4.8 - 5.2 V between the signal circuit terminal 3 and ground.

• If less than 4.8 V

1. Ignition OFF, disconnect the 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.
   • Go to next step: If infinite resistance
3. Test for less than 2 Ω in the signal circuit end to end.
   • If 2 Ω or greater, repair the open/high resistance in the circuit.
   • If less than 2 Ω, replace the K33 HVAC Control Module.

• If greater than 5.2 V

1. Ignition OFF, disconnect the harness connector at the K33 HVAC Control Module, ignition ON.
2. Test for less than 1 V between the signal circuit and ground.
   • If 1 V or greater, repair the short to voltage on the circuit.
   • If less than 1 V, replace the K33 HVAC Control Module.

• Go to next step: If between 4.8 - 5.2 V

4. 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 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.
   • Go to next step: If infinite resistance
3. Test for less than 2 Ω in the signal circuit end to end.
   • If 2 Ω or greater, repair the open/high resistance in the circuit.
   • If less than 2 Ω, replace the K33 HVAC Control Module.

• If greater than for 5.2 V

1. Ignition OFF, disconnect the harness connector at the K33 HVAC Control Module, ignition ON.
2. Test for less than 1 V between the signal circuit and ground.
   • If 1 V or greater, repair the short to voltage on the circuit.
   • If less than 1 V, replace the K33 HVAC Control Module.

• Go to next step: If between 4.8 - 5.2 V

5. Test or replace the B10B Ambient Light/Sunload Sensor.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

• HVAC Component Replacement Reference
• Control Module References for control module replacement, programming and setup

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