For 1990-2009 cars

### 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 B0183 03: Left Solar Load Sensor 1 Circuit Voltage Below Threshold
DTC B0183 07: Left Solar Load Sensor 1 Circuit Voltage Above Threshold
DTC B0188 03: Right Solar Load Sensor 2 Circuit Voltage Below Threshold
DTC B0188 07: Right Solar Load Sensor 2 Circuit Voltage Above Threshold

### Diagnostic Fault Information

Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance
--- | --- | --- | --- | ---
Left Solar Load Sensor 1 Circuit | B0183 03 | B0183 07 | B0183 07 | --
Right Solar Load Sensor 2 Circuit | B0188 03 | B0188 07 | B0188 07 | --

### Circuit Description

The sunload sensor is a photo diode. The vehicle uses left and right sunload sensors. The two sensors are integrated into the sunload sensor assembly along with the ambient light sensor. Ground and signal circuits enable the sensors to operate. As the sunload increases, the sensor signal decreases. The sensor signal varies between 0 and 5 volts. The HVAC control module converts the signal to a range between 0 and 3906.6 W/m². The sunload sensor provides the HVAC control module with a measurement of the amount of light shining on the vehicle. Bright or high intensity light causes the vehicles interior temperature to increase. The HVAC system compensates for the increased temperature by diverting additional cool air into the vehicle. The following DTCs are for the left and right sunload sensors.

### Conditions for Running the DTC

The ignition is ON.

### Conditions for Setting the DTC

The HVAC control module detects the signal circuit is less than 0 W/m² or greater than 3900 W/m².

### Action Taken When the DTC Sets

• | If the DTC is set the system will act as if no sunload condition exists.

• | A warning will display on the Driver Information Center (DIC) "Service Air Conditioning System"

### Conditions for Clearing the DTC

• | The condition for setting the DTC is no longer present.

• | The history DTC will clear after 50 fault-free ignition cycles.

• | The DTC can be cleared using a scan tool.

### Reference Information

#### Schematic Reference

HVAC Schematics

#### Connector End View Reference

Component Connector End Views

#### Electrical Information Reference

• | Circuit Testing

• | Connector Repairs

• | Testing for Intermittent Conditions and Poor Connections

• | Wiring Repairs

#### Scan Tool Reference

Control Module References

### Circuit/System Testing

1. Ignition OFF, disconnect the harness connector at the sunload sensor.
2. Ignition OFF, test for less than 10 ohms between the low reference circuit terminal C and ground.

⇒ | If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the HVAC control module.

3. Ignition ON, verify the scan tool Sun Load Sensor parameter is greater than 3900.0 W/m².

⇒ | If less than the specified range, test the signal circuit terminal listed below for a short to ground. If the circuit tests normal, replace the HVAC control module.

• | Left solar load sensor circuit terminal A.

• | Right solar load sensor circuit terminal B.

4. Install a 3A fused jumper wire between the signal circuit terminal A or B and the low reference circuit terminal C. Verify the scan tool Sun Load Sensor Parameter is less than 1 W/m².

⇒ | If greater than the specified range, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the HVAC control module.

5. If all circuits test normal, test or replace the sunload sensor.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• | Sunload and Twilight Sentinel Sensor Replacement

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