Test Description

The numbers below refer to the step numbers on the diagnostic table. See Fig 1 and Fig 2 .

1. 3
   
   Tests for the proper operation of the circuit in the low voltage range.
2. 4
   
   Tests for the proper operation of the circuit in the high voltage range. If the fuse in the jumper opens when you perform this test, the signal circuit is shorted to ground.
3. 5
   
   Tests for a short to voltage in the 5 volt reference circuit.
4. 13
   
   After replacement of the BCM you must calibrate the new module for proper operation.

Fig 1: DTC B2647 Diagnostic Table (Steps 1-3)

Courtesy of GENERAL MOTORS CORP.

Fig 2: DTC B2647 Diagnostic Table (Steps 4-14)

Courtesy of GENERAL MOTORS CORP.