GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Saturn 🢒 2003 🢒 L300/LW300 🢒 DTC 🢒 DTC B0185 or B0186

Object Number: 1256048 Size: MF
Blower Motors and Actuators
Master Electrical Component List

Circuit Description
    • B0185 solar load sensor circuit low - short to ground on signal circuit.
    • B0186 solar load sensor circuit high - short to voltage or open on low reference or signal circuit.

The ambient light sensor is a 2-wire photo diode. 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 ambient light 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 vehicle.

Conditions for Running the DTC
    • The ignition is in the RUN position.
    • Any of the conditions for setting the DTC are met for 60 seconds.

Conditions for Setting the DTC

The HVAC control module detects the signal circuit is less than 0.09 volts (6 counts) or more than 4.90-5 volts (251 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 a failure.
    • The history DTC will clear after 40-fault free ignition cycles.
    • The DTC can be cleared with a scan tool.

Test Description

The numbers below refer to the step numbers on the diagnostic table.

  1. Tests for the proper operation of the circuit in the high voltage range.

    2.

  2. 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

Values

Yes

No

Connector End View Reference: HVAC Connector End Views

1

Did you perform the HVAC Diagnostic System Check?

--

Go to Step 2

Go to Diagnostic System Check - HVAC Systems - Automatic

2
  1. Install a scan tool.
  2. Turn ON the ignition, with the engine OFF.
  3. With a scan tool, observe the Solar Sensor parameter in the HVAC control module data list.

Does the scan tool indicate that the Solar Sensor parameter is with in the specified range?

6-251 counts

Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems

Go to Step 3

3

  1. Turn OFF the ignition.
  2. Disconnect the sunload sensor.
  3. Turn ON the ignition, with the engine OFF.
  4. With a scan tool, observe the Solar Sensor parameter in the HVAC control module data list.

Does the scan tool indicate that the Solar Sensor parameters are greater than the specified value?

251 counts

Go to Step 4

Go to Step 5

4

  1. Turn OFF the ignition.
  2. Connect a 3-amp fused jumper wire between the driver or passenger signal circuit of the ambient light sensor assembly and the low reference circuit of the sunload sensor assembly.
  3. Turn ON the ignition, with the engine OFF.
  4. With a scan tool, observe the Solar Sensor parameter in the HVAC control module data list.

Does the scan tool indicate that the Solar Sensor parameter is less than the specified value?

6 counts

Go to Step 9

Go to Step 6

5

Test the signal circuit of the ambient light 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 13

Go to Step 10

6

Test the signal circuit of the ambient light 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 13

Go to Step 7

7

Test the low reference circuit of the ambient light 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 13

Go to Step 8

8

Test the following signal circuits for a short to voltage:

    • Evaporator temperature sensor
    • Ambient air temperature sensor
    • Inside air temperature sensor
    • Ambient light sensor

Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 13

Go to Step 10

9

Inspect for poor connections at the harness connector of the ambient light 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 13

Go to Step 11

10

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 13

Go to Step 12

11

Replace the ambient light sensor. Refer to Ambient Light Sensor Replacement in Lighting Systems.

Did you complete the replacement?

--

Go to Step 13

--

12

Replace the HVAC control module. Refer to HVAC Control Module Replacement .

Did you complete the replacement?

--

Go to Step 13

--

13
  1. Use the scan tool in order to clear the DTCs.
  2. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text.

Does the DTC reset?

--

Go to Step 2

System OK