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 B0183 06: Solar Load Sensor 1 Circuit Short to Ground or Open

DTC B0188 06: Solar Load Sensor 2 Circuit Short to Ground or Open

Diagnostic Fault Information

Circuit

Short to Ground

Open/High Resistance

Short to Voltage

Signal Performance

Ambient Air Temperature Sensor Signal

B0158 06

B0158 06

B0158 07*

B0158 03, B0158 07

Inside Air Temperature Sensor Signal

B0163 06

B0163 06

B0163 06*

1

Left Sunload Sensor Signal

B0183 06

B0183 06

B0183 06*

1

Right Sunload Sensor Signal

B0188 06

B0188 06

B0188 06*

1

Evaporator Temperature Sensor Signal

B3933 06

B3933 06

B3933 06*

1

Low Reference

--

B3933 06, B0158 06, B0163 06

B3933 06, B0158 07, B0163 06

B0158 07

Sunload Sensors Ground

--

B0183 06, B0188 06

B0183 06, B0188 06

--

*If the signal circuit is shorted to voltage B0158, B0163, B0183, B0188 and B3933 will all set.

1. Air Temperature Malfunction

Circuit/System Description

The sunload sensor is a 2-wire photo diode. The vehicle uses left and right sunload sensors. The 2 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 very 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 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.

Conditions for Running the DTC

Ignition 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

    • The HVAC control module will display dashes for outside air temperature.
    • 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 100 fault-free ignition cycles.

Reference Information

Schematic Reference

HVAC Schematics

Connector End View Reference

Component Connector End Views

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 Testing

  1. Ignition OFF, disconnect the harness connector at the sunload sensor.
  2. Test for less than 1.0 ohm between the ground circuit terminal C and ground.
  3. If greater than the specified range, test the ground circuit for an open/high resistance.
  4. Ignition ON, verify the appropriate scan tool Sunload Sensor parameter is greater than 250 counts.
  5. If not the specified value, test the appropriate signal circuit terminal listed below for a short to ground. If the circuit tests normal, replace the HVAC control module.
    • Left sunload sensor circuit terminal A
    • Right sunload sensor circuit terminal B
  6. Install a 3A fused jumper wire between the ground circuit terminal C and the signal circuit terminal of the appropriate sensor listed below. Verify the appropriate scan tool Sunload Sensor parameter is less than 5 counts.
  7. • Left sunload sensor circuit terminal A
    • Right sunload sensor circuit terminal B
    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.
  8. If all circuits test normal, test or replace the sunload sensor.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

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