GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Buick 🢒 2000 🢒 Regal 🢒 HVAC 🢒 HVAC Systems - Automatic 🢒 DTC B0348 Sunload Temperature Sensor Open

Object Number: 598764 Size: MF
HVAC Components
Air Temperature Sensors
Air Temperature Sensors
Handling Electrostatic Discharge Sensitive Parts Notice

Circuit Description

The heater-A/C control determines the amount of sunlight produced by the sun through an input from the sun load temperature sensor. The heater-A/C control receives a voltage signal from the sun load temperature sensor through circuit 590 (LT BLU/BLK). The sun load temperature sensor is grounded by the heater-A/C control through circuit 61 (YEL).

As the sunlight increases, the electric current flowing through the sun load temperature sensor increases. When the heater-A/C control is in AUTO mode, the heater-A/C control uses the sun load temperature sensor information in order to control the blower speed and the BI-LEVEL modes.

Conditions for Setting the DTC

The heater-A/C control performs a check on the operation of the sun load temperature sensor and detects an open in circuit 590 (LT BLU/BLK).

Action Taken When the DTC Sets

The heater-A/C control stores DTC B0348 in memory.

Conditions for Clearing the DTC
    • An open in circuit 590 (LT BLU/BLK) is no longer present.
    • Under all fault conditions, the ignition switch must be cycled from on to off, back to on before this DTC can change from current to history.
    • A history DTC clears after 100 drive cycles if a short to ground in circuit 590 (LT BLU/BLK) is no longer present.
    • Using a scan tool

Diagnostic Aids

The following conditions may cause this DTC to set:

    • A poor connection or open in circuit 590 (LT BLU/BLK)
    • A poor connection or open in circuit 61 (YEL)
    • A faulty sun load temperature sensor
    • A faulty heater-A/C control

Test Description

The number(s) below refer to the step number(s) on the diagnostic table.

  1. This step checks for proper voltage value at the sun load temperature sensor.

    2.

  2. This step checks for a short to ground in 590 (LT BLU/BLK) .

Step

Action

Value(s)

Yes

No

1

Was the heater-A/C control diagnostic system check performed?

--

Go to Step 2

Go to Diagnostic System Check

2

  1. Turn the ignition switch off.
  2. Disconnect the sun load temperature sensor connector.
  3. Turn the ignition switch on.
  4. Set the heater-A/C control in the AUTO position.
  5. Use a digital multimeter (DMM) to measure the voltage between the sun load temperature sensor harness connector terminal A and ground.

Is the measured voltage within the specified value?

4.5-5.5V

Go to Step 3

Go to Step 4

3
  1. Check the sun load temperature sensor connector for poor terminal contact. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.
  2. Replace the sun load temperature sensor if the connection is OK. Refer to Sun Load Sensor Replacement .

Is the repair complete?

--

Go to Step 7

--

4

  1. Turn the ignition switch off.
  2. Disconnect the heater-A/C control connector.
  3. Use a DMM to measure the resistance between the heater-A/C control harness connector terminal C2 and ground.

Is the measured resistance same as the specified value?

∞

Go to Step 6

Go to Step 5

5

Locate and repair a short to ground in circuit 590 (LT BLU/BLK). Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Is the repair complete?

--

Go to Step 7

--

6

Replace the heater-A/C control. Refer to Control Assembly Replacement .

Is the repair complete?

--

Go to Step 7

--

7

Operate the system to verify that it operates properly.

Does the system operate properly?

--

System OK

Go to Diagnostic System Check