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 05: Solar Load Sensor 1 Circuit Short to Short to Battery or Open
DTC B0183 02: Solar Load Sensor 1 Circuit Short to Ground
DTC B0188 05: Solar Load Sensor 2 Circuit Short to Short to Battery or Open
DTC B0188 02: Solar Load Sensor 2 Circuit Short to Ground

### Diagnostic Fault Information

Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance
--- | --- | --- | --- | ---
Ambient Air Temperature Sensor Signal | B0158 02 | B0158 05 | B0158 05 | --
Inside Air Temperature Sensor Signal | B0163 02 | B0163 05 | B0163 05 | --
Upper Air Temperature Sensor Signal | B0173 02 | B0173 05 | B0173 05 | --
Lower Air Temperature Sensor Signal | B0178 02 | B0178 05 | B0178 05 | --
Left Sunload Sensor Signal | B0183 02 | B0183 05 | B0183 05 | --
Right Sunload Sensor Signal | B0188 02 | B0188 05 | B0188 05 | --
Evaporator Temperature Sensor Signal | B3933 02 | B3933 05 | B3933 05 | --
Low Reference | -- | B3933 05, B0158 05, B0163 05 | B3933 05, B0158 05, B0163 05 | --
Sunload sensors Ground Circuit | -- | B0183 05, B0188 05 | B0183 05, B0188 05 | --

### Circuit Description

The sunload sensor is a 2-wire 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. Body ground and signal circuits enable the sensor to operate. As the sunload increases, the sensor signal decreases. The sensor operates within an intensity range between completely dark and very bright. The sensor signal varies between 0 and 5 volts. The HVAC control module converts the signal to a range between 0 and 255 counts. 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.

• | B0183 is for the left sunload sensor.

• | B0188 is for the right sunload sensor.

### 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 5 counts or more than 250 counts.

### Action Taken When the DTC Sets

• | The driver information center (DIC) will display SERVICE A/C SYSTEM.

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

### Conditions for Clearing the DTC

• | The DTC will become history if the HVAC control module no longer detects the condition that set the DTC.

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

### Reference Information

#### Schematic Reference

HVAC Schematics

#### Connector End View Reference

Component Connector End Views

#### Description and Operation

• | Air Temperature Description and Operation

• | Air Delivery 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

Ignition ON, observe the appropriate scan tool Sunload Sensor. The reading should be between 5 and 250 counts and change with sunlight changes.

### Circuit/System Testing

Important: If a solar load sensor has an out of range condition caused by a short to voltage, short to ground, or an open/high resistance, the scan tool will display the same value: 225 counts.

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

⇒ | If greater than the specified range, test the ground circuit for an open/high resistance.

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

• | Left solar load sensor circuit terminal A.

• | Right solar load sensor circuit terminal B.

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

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

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

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• | Ambient Light Sensor Replacement

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