Test Description

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

3. Tests for the proper operation of the ambient light sensor signal circuit in the low voltage range.
4. Tests for the proper operation of the ambient light sensor signal circuit in the high voltage range. If the fuse in the jumper opens when you perform this test, the ambient light sensor signal circuit is shorted to ground.
5. Tests for a short to voltage in the 5 volt reference circuit.
13. After replacement of the BCM you must calibrate the new module for proper operation.

Fig 1: DTC B2647 (Steps 1-3)

Courtesy of GENERAL MOTORS CORP.

Fig 2: DTC B2647 (Steps 4-14)

Courtesy of GENERAL MOTORS CORP.