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For 1990-2009 cars only
Makes 🢒 Buick 🢒 1999 🢒 Century 🢒 DTC 🢒 DTC B0348 Sunload Temperature Sensor Open

Object Number: 308550 Size: SF
HVAC Components
HVAC Air Delivery/Temperature Control Schematics
HVAC Air Delivery/Temperature Control Schematics
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, it uses the sun load temperature sensor information to control the blower speed and 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 range?

4.5-5.5V

Go to Step 3

Go to Step 4

3

Check the sun load temperature sensor connector for poor terminal contact. Replace the sun load temperature sensor if the connection is OK. Refer to Sun Load Sensor Replacement .

Is the repair complete?

--

System OK

--

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) .

Is the repair complete?

--

System OK

--

6

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

Is the repair complete?

--

System OK

--