Code P103, Open Brake Booster Vacuum (BBV) Sensor: Action

PCM turns on SERVICE VEHICLE SOON message.

NOTE: Test numbers refer to numbers on diagnostic chart.

If brake booster vacuum sensor is open PD84 should read -8 kPa or less.
If brake booster vacuum sensor is open, PD84 should read 82-84 kPa with sensor terminals jumpered together.
Checks circuit No. 1726 for short to ground between BBV and PCM.
Checks circuit No. 1726 for open between BBV and PCM.

Fig 1: Code P103 Schematic, Open Brake Booster Vacuum (BBV) Sensor

Courtesy of GENERAL MOTORS CORP.

Fig 2: Code P103 Diagnostic Flow Chart, Open BBV Sensor

Courtesy of GENERAL MOTORS CORP.