Toyota Yaris: Stop And Start System / Brake Booster Pressure Sensor Circuit Short to Ground (P055511,P055515)

Toyota Yaris XP210 (2020-2025) Reapir and Service Manual / Engine & Hybrid System / Stop And Start / Stop And Start System / Brake Booster Pressure Sensor Circuit Short to Ground (P055511,P055515)

DESCRIPTION

The engine stop and start ECU determines changes in the brake booster assembly pressure based on the voltage signal received from the vacuum sensor assembly in the brake booster assembly.

If the engine stop and start ECU judges that the signal received from the vacuum sensor assembly is abnormal, it stores DTC P055511 or P055515 and blinks the stop and start cancel indicator.

DTC No.	Detection Item	DTC Detection Condition	Trouble Area	Warning Indicate	Memory	Note
P055511	Brake Booster Pressure Sensor Circuit Short to Ground	Both of the following conditions are met for 2 seconds or more (1 trip detection logic): Short in vacuum sensor assembly circuit. Ignition switch ON.	Wire harness or connector Vacuum sensor assembly Engine stop and start ECU	Blinks	DTC stored	SAE Code: P0557
P055515	Brake Booster Pressure Sensor Circuit Short to Battery or Open	Both of the following conditions are met for 2 seconds or more (1 trip detection logic): Open or short in vacuum sensor assembly circuit. Ignition switch ON.	Wire harness or connector Vacuum sensor assembly Engine stop and start ECU	Blinks	DTC stored	SAE Code: P0558

CONFIRMATION DRIVING PATTERN

CONFIRMATION AFTER TROUBLESHOOTING

HINT:

If the cable is disconnected from the auxiliary battery terminal, stop and start control is prohibited until refresh charge is completed.
In this case, let the vehicle idle to complete the refresh charge. The refresh charge is complete when the Data List item Status of Auxiliary Battery Charge Control changes from "Refresh Charge Mode". (Usually, idling the engine for 5 to 60 minutes with the auxiliary battery fluid temperature at 11°C (52°F) or higher, the refresh charge will be completed.)
If the GTS is not available and the Data List item Status of Auxiliary Battery Charge Control cannot be checked, charge the auxiliary battery by idling the engine for approximately 5 to 60 minutes or driving the vehicle, and then drive the vehicle and check that stop and start control operates.
If the engine is started with the hood open, the system determines that a jump start has occurred. Therefore, make sure that the hood is closed before starting the engine and driving the vehicle.
After the refresh charge completes, turn the ignition switch off, wait for at least 30 seconds, and then start the engine again. If the vehicle enters refresh charge mode again while the engine is idling, the initial refresh charge did not properly complete, so wait for the refresh charge to complete.
Allow the engine to idle for 3 minutes after it is warmed up and check that the engine idle speed is within 50 rpm of the target idle speed.

(a) Clear the DTCs.

Powertrain > Stop and Start > Clear DTCs

(b) Start the engine and allow it to idle for 15 seconds or more.

(d) Turn the GTS on.

Powertrain > Stop and Start > Data List

Tester Display
Brake Boost Pressure

(e) While depressing the brake pedal several times, check that the Brake Boost Pressure value changes.

(f) Check that DTCs are not output.

Powertrain > Stop and Start > Trouble Codes

STOP AND START SYSTEM OPERATION CHECK

Click here

WIRING DIAGRAM

CAUTION / NOTICE / HINT

NOTICE:

Before replacing the engine stop and start ECU, read the number of starter operations and write it into a new engine stop and start ECU.
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After replacing the engine stop and start ECU, perform learning of the external backup boost converter (eco run vehicle converter assembly).
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After replacing the engine stop and start ECU or air conditioning amplifier assembly, reset and perform learning of the air conditioning information in the engine stop and start ECU.
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HINT:

Using the GTS, read the freeze frame data before troubleshooting. System condition information is recorded as freeze frame data the moment a DTC is stored. This information can be useful when troubleshooting.
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For wire harness and connector inspection procedures and precautions, refer to " Click here "
DTCs for the stop and start system are not cleared even if the malfunction has been repaired. After repairing the malfunction, be sure to clear the DTCs.
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PROCEDURE

1.	CHECK HARNESS AND CONNECTOR (PB TERMINAL VOLTAGE)

Component with harness connected

(Engine Stop and Start ECU)

(a) Turn the ignition switch to ON.

(b) Measure the voltage according to the value(s) in the table below.

Standard Voltage:

Tester Connection	Switch Condition	Specified Condition	Proceed to
A67-13 (PB) - A67-3 (BRE2)	Ignition switch ON	Higher than 0.6 V or below 4.7 V	A
A67-13 (PB) - A67-3 (BRE2)	Ignition switch ON	None of the above conditions are met	B

USE SIMULATION METHOD TO CHECK

2.	CHECK HARNESS AND CONNECTOR (ENGINE STOP AND START ECU - VACUUM SENSOR ASSEMBLY)

(a) Disconnect the A67 engine stop and start ECU connector.

(b) Disconnect the A28 vacuum sensor assembly connector.

Standard Resistance:

Tester Connection	Condition	Specified Condition
A67-13 (PB) - A28-2 (PB)	Always	Below 1 Ω
A67-14 (BRVC) - A28-3 (VC)	Always	Below 1 Ω
A67-3 (BRE2) - A28-1 (E2)	Always	Below 1 Ω
A67-13 (PB) - Body ground and other terminals	Always	10 kΩ or higher
A67-14 (BRVC) - Body ground and other terminals	Always	10 kΩ or higher
A67-3 (BRE2) - Body ground and other terminals	Always	10 kΩ or higher
A28-2 (PB) - Body ground and other terminals	Always	10 kΩ or higher
A28-3 (VC) - Body ground and other terminals	Always	10 kΩ or higher
A28-1 (E2) - Body ground and other terminals	Always	10 kΩ or higher

REPAIR OR REPLACE HARNESS OR CONNECTOR

3.	CHECK ENGINE STOP AND START ECU (BRVC TERMINAL VOLTAGE)

Component with harness connected

(Engine Stop and Start ECU)

(a) Turn the ignition switch to ON.

(b) Measure the voltage according to the value(s) in the table below.

Standard Voltage:

Tester Connection	Switch Condition	Specified Condition
A67-14 (BRVC) - A67-3 (BRE2)	Ignition switch ON	4.5 to 5.5 V

REPLACE ENGINE STOP AND START ECU

4.	REPLACE VACUUM SENSOR ASSEMBLY

Click here

CLEAR DTC

(a) Clear the DTC.

Powertrain > Stop and Start > Clear DTCs

6.	CHECK DTC OUTPUT

(a) Start the engine and warm it up.

Powertrain > Stop and Start > Data List

Tester Display
Brake Boost Pressure

(b) While depressing the brake pedal several times, check that the Brake Boost Pressure value changes.

Powertrain > Stop and Start > Trouble Codes

Result	Proceed to
P055511 or P055515 is not output	A
DTC P055511 or P055515 is output	B

END

REPLACE ENGINE STOP AND START ECU

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