GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 1998 🢒 Sonoma Pickup - 4WD 🢒 DTC 🢒 DTC B0185 Solar Load Sensor 1 Circuit Low

Object Number: 283804 Size: MF

Circuit Description

The solar load sensor is a reverse bias photo diode that measures sun load on the vehicle. The sensor is an input to the heater and A/C control module. High sensor impedance equates to full darkness. Low sensor impedance equates to bright sunlight. Refer to Sensor Resistance Table .

Conditions for Setting the DTC

With the ignition ON, the heater and A/C control module will detect DTC B0185 any time that CKT 590 is at or near zero voltage.

Action Taken When the DTC Sets

The heater and A/C control module will use a default value of approximately 200 A/D counts until the fault is cleared.

Conditions for Clearing the MIL/DTC

This fault will clear as soon as the fault goes away or has been repaired. The system will then return to normal operation. History DTCs can only be cleared by removing and restoring B+ or by using the scan tool.

Diagnostic Aids
    • The heater and A/C control module may set class 2 lost communication DTCs when the BCM or the VCM is being reprogrammed. After reprogramming, inspect for DTCs in the heater and A/C control module. Clear any history U DTCs, then resume diagnostics.
    • Visually inspect the sensor connector and harness for corrosion and damage.

Test Description

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

  1. This step inspects for a short to ground in CKT 590.

    2.

  2. This step inspects for the display of sensor counts in the SCAN TOOL.

    3.

  3. This step repairs the short to ground in CKT 590.

    4.

  4. This step replaces a defective solar load sensor.

    5.

  5. This step inspects for a malfunctioning heater and A/C control module.

    6.

  6. This step replaces a defective heater and A/C control module.

Step

Action

Value(s)

Yes

No

1

  1. Turn the ignition to the OFF position.
  2. Disconnect the solar load sensor.
  3. Disconnect the heater and A/C control module.
  4. Use a J 39200 DMM in order to inspect for a short to ground in CKT 590 (LT BLU/BLK) at terminal C1 of the heater and A/C control module connector.

Is the resistance less than the specified value?

5 ohms

Go to Step 3

Go to Step 2

2

  1. Reconnect the solar load sensor.
  2. Reconnect the heater and A/C control module.
  3. Turn the ignition to the ON position.
  4. Cover up the solar load sensor in the defroster grille.
  5. Read the solar load sensor counts in the scan tool.

Are the counts equal to or less than the specified value?

20 counts

Go to Step 4

Go to Step 5

3

Repair the short to ground in CKT 590 (LT BLU).

Is the repair complete?

--

Go to Diagnostic System Check

--

4

Replace the solar load sensor.

Is the repair complete?

--

Go to Diagnostic System Check

--

5

  1. Clear the heater and A/C control module DTCs.
  2. Inspect for heater and A/C control module DTCs.

Does the DTC reset?

--

Go to Step 6

Go to Intermittents and Poor Connections Diagnosis

6

Replace the heater and A/C control module.

Is the repair complete?

--

Go to Diagnostic System Check

--