DTC P0556: Brake Booster Pressure Sensor Circuit Range/Performance: Wiring Diagram

WARNING: This page is about a different car, the 2015 Subaru XV Crosstrek. However, it is still accessible from the selected car via links, so may be relevant.

Hybrid system < Ref. to WIRING DIAGRAM , Hybrid Electric Vehicle System.>

Fig 1: Brake Booster Pressure Sensor - Wiring Diagram

Courtesy of SUBARU OF AMERICA, INC.

DTC PROCEDURE

Step	Check	Yes	No
1 CHECK DTC. Read the DTC. < Ref. to HYBRID POWERTRAIN CONTROL SYSTEM , OPERATION, Read Diagnostic Trouble Code (DTC).>	Are any other DTCs (brake booster pressure sensor related) detected? (current malfunction)	First diagnose other DTCs.	Go to step 2 .
2 CHECK CURRENT DATA. Using the Subaru Select Monitor, confirm the current data of hybrid powertrain control system, the value of «Power Sensor Voltage 1»«Power Sensor Voltage 2». < Ref. to HYBRID POWERTRAIN CONTROL SYSTEM , OPERATION, Read Current Data.>	Is the value approx. 5 V?	Go to step 3 .	Go to step 9 .
3 CHECK CURRENT DATA. Turn the ignition switch to ON. Depress the brake pedal 10 times. Using the Subaru Select Monitor, confirm the current data of hybrid powertrain control system, the value of «Brake Booster Pressure 1»«Brake Booster Pressure 2»«Atmosphere Pressure». < Ref. to HYBRID POWERTRAIN CONTROL SYSTEM , OPERATION, Read Current Data.>	Do «Brake Booster Pressure 1»«Brake Booster Pressure 2»«Atmosphere Pressure» match?	Even if DTC is detected, the circuit has returned to a normal condition at this time. Reproduce the failure, and then perform the diagnosis again. NOTE: In this case, temporary poor contact of connector, temporary open or short circuit of harness may be the cause.	Go to step 4 .
4 CHECK SENSORS. Interchange brake booster pressure sensor 1 and brake booster pressure sensor 2. Turn the ignition switch to ON. Depress the brake pedal 10 times. Using the Subaru Select Monitor, confirm the current data of hybrid powertrain control system, the value of «Brake Booster Pressure 1»«Brake Booster Pressure 2». < Ref. to HYBRID POWERTRAIN CONTROL SYSTEM , OPERATION, Read Current Data.>	Did those two values interchange each other?	Replace the brake booster. < Ref. to BRAKE BOOSTER .>	Go to step 5 .
5 CHECK CURRENT DATA. Using the Subaru Select Monitor, confirm the current data of hybrid powertrain control system, the value of «Brake Booster Pressure Sensor Voltage 1»«Brake Booster Pressure Sensor Voltage 2». < Ref. to HYBRID POWERTRAIN CONTROL SYSTEM , OPERATION, Read Current Data.>	Is the value between 0.3 - 4.7 V?	Even if DTC is detected, the circuit has returned to a normal condition at this time. Reproduce the failure, and then perform the diagnosis again. NOTE: In this case, temporary poor contact of connector, temporary open or short circuit of harness may be the cause.	If 0.3 V or less Go to step 6 . If 4.7 V or more Go to step 7 .
6 CHECK HARNESS (SHORT TO GROUND). Disconnect the connectors of brake booster pressure sensor 1 and brake booster pressure sensor 2 and the HPCM connector. Using a tester, measure the resistance between brake booster pressure sensor 1 and brake booster pressure sensor 2 connectors and chassis ground. Connector & terminal (B565) No. 2 - Chassis ground: (B600) No. 2 - Chassis ground:	Is the resistance 1 MΩ or more?	Replace the HPCM. < Ref. to HYBRID POWERTRAIN CONTROL MODULE .>	Repair the ground short circuit of harness between HPCM connector and brake booster pressure sensor connector.
7 CHECK HARNESS (OPEN CIRCUIT). Disconnect the connectors of brake booster pressure sensor 1 and brake booster pressure sensor 2. Using a tester, measure the resistance between brake booster pressure sensor 1 and brake booster pressure sensor 2 connectors and the HPCM connector. Connector & terminal (B565) No. 2 - (B606) No. 3: (B600) No. 2 - (B606) No. 4:	Is the resistance 1 Ω or less?	Go to step 8 .	Repair the open circuit of harness between HPCM connector and brake booster pressure sensor connector.
8 CHECK HARNESS (SHORT TO POWER). Turn the ignition switch to ON. Using a tester, measure the voltage between brake booster pressure sensor 1 and brake booster pressure sensor 2 connectors and chassis ground. Connector & terminal (B565) No. 2 (+) - Chassis ground (-): (B600) No. 2 (+) - Chassis ground (-):	Is the voltage 5 V or less?	Replace the HPCM. < Ref. to HYBRID POWERTRAIN CONTROL MODULE .>	Repair short circuit to power in harness between HPCM connector and brake booster pressure sensor connector.
9 CHECK CURRENT DATA. Disconnect the HPCM connector (B606). Turn the ignition switch to ON. Using the Subaru Select Monitor, confirm the current data of hybrid powertrain control system, the value of «Power Sensor Voltage 1»«Power Sensor Voltage 2».	Is the value approx. 5 V?	Go to step 1 .	Replace the HPCM. < Ref. to HYBRID POWERTRAIN CONTROL MODULE .>
10 CHECK HARNESS (OPEN CIRCUIT). Disconnect the connectors of brake booster pressure sensor 1 and brake booster pressure sensor 2. Using a tester, measure the resistance between brake booster pressure sensor 1 and brake booster pressure sensor 2 connectors and the HPCM connector. Connector & terminal (B565) No. 3 - (B606) No. 7: (B600) No. 3 - (B606) No. 17:	Is the resistance 1 Ω or less?	Go to step 1 .	Repair the open circuit of harness between HPCM connector and brake booster pressure sensor connector.
11 CHECK HARNESS (SHORT TO GROUND). Disconnect the connectors of brake booster pressure sensor 1 and brake booster pressure sensor 2. Using a tester, measure the resistance between brake booster pressure sensor 1 and brake booster pressure sensor 2 connectors and chassis ground. Connector & terminal (B565) No. 3 - Chassis ground: (B600) No. 3 - Chassis ground:	Is the resistance 1 MΩ or more?	Replace the HPCM. < Ref. to HYBRID POWERTRAIN CONTROL MODULE .>	Repair the ground short circuit of harness between HPCM connector and brake booster pressure sensor connector.