Circuit Description
The HVAC control module monitors the ambient light on the vehicle via light sensitive photodiode which is called a sunload sensor. The HVAC control module uses this information in order to compensate for the effect of the sun on the inside air temperature of the vehicle. When the sensor is in direct sunlight, the ambient light counts are low. When the sensor is shaded, the ambient light counts are high. The HVAC control module requests engagement of the A/C compressor clutch, and controls the door position of the air temperature actuator in order to maintain the selected air temperature on the HVAC control module.
Conditions for Running the DTC
The ignition is turned ON.
Conditions for Setting the DTC
The HVAC control module detects that the signal circuit is less than 5 counts, for B0185, or 250 counts, for B0186.
Action Taken When the DTC Sets
The HVAC control module uses a default sunload sensor value until the fault is cleared.
Conditions for Clearing the DTC
| • | The DTC becomes history when the HVAC control module no longer detects a failure. |
| • | The history DTC clears after 50 fault free ignition cycles. |
| • | The DTC can be cleared with a scan tool. |
Diagnostic Aids
| • | Insure sun load sensor is in place and secure. Insure no debris around sun load sensor this will give incorrect reading to HVAC control module. |
| • | If condition is not present, refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems. |
Test Description
The numbers below refer to the step numbers on the diagnostic table.
-
Tests for the proper operation of the circuit in the high voltage range.
-
Tests for the proper operation of the circuit in the low voltage range. If the fuse in the jumper opens when you perform this test, the signal circuit is shorted to voltage.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
Schematic Reference: HVAC Schematics Connector End View Reference: HVAC Connector End Views | ||||
1 | Did you perform the HVAC Diagnostic System Check? | -- | Go to Step 2 | |
2 |
Does the scan tool indicate that the Solar Sensor parameter is within the specified range? | 100-240 counts | Go to Diagnostic Aids | Go to Step 3 |
Does the scan tool indicate that the Solar Sensor parameter is greater than the specified value? | 250 counts | Go to Step 4 | Go to Step 5 | |
Does the scan tool indicate that the Solar Sensor parameter is less than the specified value? | 5 counts | Go to Step 8 | Go to Step 6 | |
5 | Test the signal circuit of the sunload sensor for a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 12 | Go to Step 9 |
6 | Test the signal circuit of the sunload sensor for a short to voltage, a high resistance, or an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 12 | Go to Step 7 |
7 | Test the low reference circuit of the sunload sensor for a high resistance or an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 12 | Go to Step 9 |
8 | Inspect for poor connections at the harness connector of the sunload sensor. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 12 | Go to Step 10 |
9 | Inspect for poor connections at the harness connector of the HVAC control module. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 12 | Go to Step 11 |
10 | Replace the sunload sensor. Refer to Sun Load Sensor Replacement Did you complete the replacement? | -- | Go to Step 12 | -- |
11 |
Important: : Perform the recalibration procedure for the HVAC control module. Replace the HVAC control module. Refer to HVAC Control Module Replacement . Did you complete the replacement? | -- | Go to Step 12 | -- |
12 |
Does the DTC reset? | -- | Go to Step 2 | System OK |
