GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 1998 🢒 Sonoma Pickup - 2WD 🢒 DTC 🢒 DTC B0186 Solar Load Sensor 1 Circuit High

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.

Conditions for Setting the DTC

With the ignition ON, the heater and A/C control module will detect DTC B0186 any time that CKT 590 is at or near 5 volts or higher.

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 B+ on CKT 590.

    2.

  2. This step determines is the short to B+ is in CKT 590 or in the heater and A/C control module.

    3.

  3. This step inspects for an open in CKT 552.

    4.

  4. This step reads solar load sensor counts.

    5.

  5. This step replaces defective solar load sensor in #1.

    6.

  6. This step repairs an open in CKT 552.

    7.

  7. This step inspects for intermittents and tests for a malfunctioning heater and A/C control module.

    8.

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

    9.

  9. This step inspects for 5 volts on CKT 590.

    10.

  10. This step determines if the open is in CKT 590 or in the 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. Turn the ignition to the ON position.
  4. Use a J 39200 in order to measure the voltage at terminal A of the solar load sensor harness connector and ground.

Is the voltage within the specified range?

9-16 V

Go to Step 2

Go to Step 9

2

Inspect CKT 590 (LT BLU/BLK) for a short to B+.

Is the repair complete?

--

Go to Diagnostic System Check

Go to Step 8

3

Inspect for continuity to ground at terminal B of the solar load sensor harness connector and ground.

Is continuity indicated?

--

Go to Step 4

Go to Step 6

4

  1. Turn the ignition to the OFF position.
  2. Reconnect the solar load sensor.
  3. Turn the ignition to the ON position.
  4. Shine an incandescent shop light on the solar load sensor in the defroster grill.
  5. Read the solar load sensor counts in the scan tool.

Are the solar load sensor counts above the specified value?

250 counts

Go to Step 5

Go to Step 7

5

Replace the solar load sensor.

Is the repair complete?

--

Go to Diagnostic System Check

--

6

Repair the open in CKT 552 (BLK) .

Is the repair complete?

--

Go to Diagnostic System Check

Go to Step 8

7

Clear any heater and A/C control module DTCs.

Does the DTC reset?

--

Go to Step 8

Go to Intermittents and Poor Connections Diagnosis

8

Replace the heater and A/C control module.

Is the repair complete?

--

Go to Diagnostic System Check

--

9

Use a J 39200 DMM in order to ground and measure the voltage on terminal A of solar load sensor connector.

Is the voltage within the specified range?

4-6 V

Go to Step 3

Go to Step 10

10

Inspect CKT 590 (LT BLU) for an open.

Is the repair complete?

--

Go to Diagnostic System Check

Go to Step 8