B0188
DTC B0183 or B0188
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Initial Inspection and Diagnostic Overview
* 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 Description
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.
The left and right sunload sensors provide the HVAC control module with inputs as to the amount heat load the sun is placing on the interior of the vehicle. The sunload sensors are photodiodes that are sensitive to light intensity. The body control module (BCM) applies 5 volts to internal input resistors that are connected to the left and right signal circuits of the sunload sensor assembly. The BCM provides ground to the sensors through the low reference circuit. The BCM monitors the voltage drops across the sunload sensors and converts the voltage values to count values where 1 volt is approximately equal to 51 counts. As the light intensity increases, the sunload sensors allow more current to travel through the circuits and the signal voltages decrease. As the light intensity decreases, the sunload sensor allow less current to travel through the circuits and the signal voltages increase. The BCM transmits the data to the HVAC control module over the GM LAN data circuit.
Conditions for Running the DTC
The ignition is ON.
Conditions for Setting the DTC
The BCM determines that the value of the sunload sensor signal is less than 5 counts (1 volt) or greater than 250 counts (5 volts).
Action Taken When the DTC Sets
The action taken will be for the BCM to revert to a calibrated default value.
Conditions for Clearing the DTC
* The DTC will become history if the BCM no longer detects a failure.
* The history DTC will clear after 100 fault-free ignition cycles.
* The DTC can be cleared with a scan tool.
Circuit/System Testing
1. Ignition OFF, disconnect the sunload sensor harness connector at the Sunload Sensor.
2. Test for less than 1.0 ohm 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, verify the appropriate Sunload Sensor voltage parameter is greater than 4.9 volts or 250 counts.
• If less than the specified range test the appropriate signal circuit terminal A or B for a short to ground. If the circuit tests normal, replace the HVAC control module.
4. Install a 3-amp fused jumper wire between the appropriate signal circuit terminal A or B and the ground circuit terminal C. Verify the scan tool sunload count parameter is less than the 0.1 volt or 5 counts.
• If greater than the specified value, 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, replace the Sunload Sensor.
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
* Daytime Running Lamp (DRL) Ambient Light Sensor Replacement (Without UV6) Daytime Running Lamp (DRL) Ambient Light Sensor Replacement (With UV6)
* Refer to Programming and Relearning for HVAC Control Module replacement, setup, and programming