GM Service Manual Online
For 1990-2009 cars only

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 B0184: Solar Load Sensor 1 Circuit Range/Performance (left)

DTC B0189: Solar Load Sensor 2 Circuit Range/Performance (right)

Diagnostic Fault Information

Circuit

Short to Ground

Open/High Resistance

Short to Voltage

Signal Performance

Left Solar Load Sensor Signal

B0184

B0184

B0184

--

Right Solar Load Sensor Signal

B0189

B0189

B0189

--

Low Reference

B0184, B0189

B0184, B0189

B0184, B0189

--

Circuit/System 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. Low reference 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 bright. The sensor signal varies between 0-5 volts. The HVAC control module converts the signal to a range between 0-255 counts. The sunload sensor provides the HVAC control module a measurement of the amount of light shining on the vehicle. Bright or high intensity light causes the vehicles inside temperature to increase. The HVAC system compensates for the increased temperature by diverting additional cool air into the passenger compartment when in the Auto mode.

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 0.09 volt (5 counts) or more than 4.90 volts (250 counts).

Action Taken When the DTC Sets

If the DTC sets due to a low voltage condition, the HVAC control module will operate the system as if a maximum sunload condition exists. If the DTC sets due to a high voltage condition, the HVAC control module will operate the system as if a minimum 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 Testing

  1. Ignition OFF, disconnect the harness connector at the sunload sensor assembly.
  2. Test for less than 2.0 ohm between the low reference circuit terminal C and ground.
  3. 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.
  4. Ignition ON, verify the Left Sunload Sensor parameter is greater than 250 counts.
  5. If not the specified value, test the signal circuit terminal A for a short to ground. If the circuit tests normal, replace the HVAC control module.
  6. Ignition ON, verify the Right Sunload Sensor parameter is greater than 250 counts.
  7. If not the specified value, test the signal circuit terminal B for a short to ground. If the circuit tests normal, replace the HVAC control module.
  8. Install a 3A fused jumper wire between the signal circuit terminal A and the low reference circuit terminal C. Verify the Left Sunload Sensor parameter is less than 5 counts.
  9. If not 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.
  10. Install a 3A fused jumper wire between the signal circuit terminal B and the low reference circuit terminal C. Verify the Right Sunload Sensor parameter is less than 5 counts.
  11. If not 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.
  12. If all circuits test normal, test or replace the sunload sensor assembly.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Sun Load Sensor Replacement
    •  Control Module References for HVAC control module replacement, setup, and programming