Toyota Avalon (XX50): Accumulator Pressure Sensor Stuck (C14D5). Open in Master Reservoir Level Switch Circuit (C120F). Open Circuit in ABS Motor Relay Circuit (C146C,C146D)

Toyota Avalon (XX50) 2019-2022 Service & Repair Manual / Brake / Brake Control / Dynamic Control Systems / Electronically Controlled Brake System(for Hv Model) / Accumulator Pressure Sensor Stuck (C14D5). Open in Master Reservoir Level Switch Circuit (C120F). Open Circuit in ABS Motor Relay Circuit (C146C,C146D)

Accumulator Pressure Sensor Stuck (C14D5)

DESCRIPTION

The accumulator pressure sensor is built into the brake booster with master cylinder assembly and detects the accumulator pressure.

If the skid control ECU (brake booster with master cylinder assembly) detects that the accumulator pressure sensor value is below the threshold, operation of the motor relay is requested and the pump motor built into the brake booster pump assembly operates.

DTC No.	Detection Item	INF Code	DTC Detection Condition	Trouble Area	MIL	Note
C14D5	Accumulator Pressure Sensor Stuck	334	When the pump motor is operating, the accumulator pressure sensor signal does not change for 14 seconds or more.	Skid control ECU (brake booster with master cylinder assembly)	Comes on	INF Code 334: SAE Code C14D5 Electronically controlled brake system DTC

MONITOR DESCRIPTION

When the volume of brake fluid within the accumulator is below a certain amount, the skid control ECU (brake booster with master cylinder assembly) operates the pump motor. When the pump motor is being operated and the output value of the accumulator pressure sensor does not change substantially for a certain period of time, the skid control ECU (brake booster with master cylinder assembly) judges that the accumulator pressure sensor has a stuck malfunction and illuminates the MIL and stores this DTC.

MONITOR STRATEGY

Related DTCs	C14D5: Accumulator pressure sensor stuck
Required Sensors/Components(Main)	Brake actuator (brake booster with master cylinder assembly) Brake booster pump assembly
Required Sensors/Components(Related)	Skid control ECU (brake booster with master cylinder assembly) Brake actuator (brake booster with master cylinder assembly) Brake booster pump assembly
Frequency of Operation	Continuous
Duration	7 to 14 seconds (Time depends on battery voltage)
MIL Operation	Immediately
Sequence of Operation	None

TYPICAL ENABLING CONDITIONS

Monitor runs whenever the following DTCs are not stored	C121D (Pump motor open circuit) C14C0 (Servo pressure sensor voltage circuit check) C14C1 (Servo pressure sensor lost communication) C14C2 (Servo pressure sensor internal malfunction) C14C3 (Servo pressure sensor exceeded learning limit) C14C4 (Servo pressure sensor intermittent/erratic) C14C5 (Servo pressure sensor invalid data) C14D0 (Accumulator pressure sensor voltage circuit check) C14D1 (Accumulator pressure sensor lost communication) C14D2 (Accumulator pressure sensor internal malfunction) C14D3 (Accumulator pressure sensor intermittent/erratic) C14D4 (Case 1) (Accumulator pressure sensor invalid data) C14D4 (Case 2) (Accumulator pressure sensor intermittent)
All of the following conditions are met	-
Accumulator pressure sensor fail	Not detected
Pump motor control circuit fail	Not detected
ABS/TRAC/VSC	Off
Accumulator pressure	17.1 MPa (174.4 kgf/cm2, 2480 psi) or more
Pump motor voltage (MTT)	Less than 6 V
Hydraulic used by brake booster	20 cm3 (1.2 cu.in.) or more
Change of accumulator pressure	Less than 0.12 MPa (1.2 kgf/cm2, 17 psi)

TYPICAL MALFUNCTION THRESHOLDS

Change of accumulator pressure while pump motor is intrusively operated

Less than 0.12 MPa (1.2 kgf/cm2, 17 psi)

COMPONENT OPERATING RANGE

All of the following conditions are met	-
Accumulator pressure sensor fail	Not detected
Accumulator pressure	Less than 20.85 MPa (212.6 kgf/cm2, 3024 psi)
Change of accumulator pressure	0.12 MPa (1.2 kgf/cm2, 17 psi) or more

CONFIRMATION DRIVING PATTERN

Connect the Techstream to the DLC3.
Turn the power switch on (IG).
Turn the Techstream on.
Clear the DTCs (even if no DTCs are stored, perform the clear DTC procedure).
Turn the power switch off.
Turn the power switch on (IG).
Turn the Techstream on.
Repeat the following step 3 times.
- Fully depress the brake pedal for 2 seconds, release it and wait 1 second.
Wait 14 seconds.
Enter the following menus: Chassis / ABS/VSC/TRAC / Trouble Codes.
Read the DTCs.
HINT:
- If a DTC is output, the system is malfunctioning.
- If a DTC is not output, perform the following procedure.
If the DTCs are not output, perform a universal trip and check for permanent DTCs.
Click here

HINT:
- If a permanent DTC is output, the system is malfunctioning.
- If no permanent DTCs are output, the system is normal.

CAUTION / NOTICE / HINT

NOTICE:

After replacing the skid control ECU (brake booster with master cylinder assembly), perform linear solenoid valve offset learning, ABS holding solenoid valve learning, yaw rate and acceleration sensor zero point calibration and system information memorization after performing "Reset Memory".

Click here

PROCEDURE

CHECK DTC

(a) Clear the DTCs.

Click here

Chassis > ABS/VSC/TRAC > Clear DTCs

(b) Turn the power switch off.

(d) Depress the brake pedal 10 times or more to operate the pump motor.

(e) After the pump motor stops, check for DTCs.

Click here

Chassis > ABS/VSC/TRAC > Trouble Codes

Result	Proceed to
DTC C14D5 is not output.	A
DTC C14D5 is output.	B

USE SIMULATION METHOD TO CHECK

REPLACE BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY

Open in Master Reservoir Level Switch Circuit (C120F)

DESCRIPTION

DTC No.	Detection Item	INF Code	DTC Detection Condition	Trouble Area	MIL	Note
C120F	Open in Master Reservoir Level Switch Circuit	371	The brake fluid level warning switch (brake booster with master cylinder assembly) circuit is open for 2 seconds or more.	Open in brake fluid level warning switch (brake booster with master cylinder assembly) Open in wire harness Skid control ECU (brake booster with master cylinder assembly)	Comes on	INF Code 371: SAE Code C120F Electronically controlled brake system DTC

MONITOR DESCRIPTION

When the voltage at terminal LBL of the skid control ECU (brake booster with master cylinder assembly) is a specific value or more (open circuit judgment range) for a certain amount of time, the skid control ECU (brake booster with master cylinder assembly) judges that there is an open in the fluid warning switch circuit and illuminates the MIL and stores this DTC.

MONITOR STRATEGY

Related DTCs	C120F: Brake fluid level warning switch open circuit
Required Sensors/Components(Main)	Brake fluid level warning switch (brake booster with master cylinder assembly)
Required Sensors/Components(Related)	Skid control ECU (brake booster with master cylinder assembly)
Frequency of Operation	Continuous
Duration	2 seconds
MIL Operation	Immediately
Sequence of Operation	None

TYPICAL ENABLING CONDITIONS

Monitor runs whenever the following DTCs are not stored	None
Serial communication with low side IC	Valid

TYPICAL MALFUNCTION THRESHOLDS

Brake fluid level warning switch voltage

Higher than 8.4 V

COMPONENT OPERATING RANGE

Both of the following conditions are met	-
Serial communication with low side IC	Valid
Brake fluid level warning switch voltage	8.4 V or less

CONFIRMATION DRIVING PATTERN

Connect the Techstream to the DLC3.
Turn the power switch on (IG).
Turn the Techstream on.
Clear the DTCs (even if no DTCs are stored, perform the clear DTC procedure).
Turn the power switch off.
Turn the power switch on (IG).
Turn the Techstream on.
Wait 2 seconds.
Enter the following menus: Chassis / ABS/VSC/TRAC / Trouble Codes.
Read the DTCs.
HINT:
- If a DTC is output, the system is malfunctioning.
- If a DTC is not output, perform the following procedure.
If the DTCs are not output, perform a universal trip and check for permanent DTCs.
Click here

HINT:
- If a permanent DTC is output, the system is malfunctioning.
- If no permanent DTCs are output, the system is normal.

WIRING DIAGRAM

Refer to DTC C1202.

Click here

CAUTION / NOTICE / HINT

NOTICE:

Click here

PROCEDURE

1.	CHECK BRAKE FLUID LEVEL

(a) Check that the brake fluid level is sufficient.

HINT:

If the fluid level is low, check for fluid leaks, and repair as necessary.

(1) Check for brake fluid leaks (connection between the brake booster pump assembly, brake actuator assembly, brake booster with master cylinder assembly and wheel cylinders).

HINT:

If no leaks exist, add and adjust fluid using the Techstream.

Click here

(b) Check that there are no leaks from the connections between the brake booster pump assembly, brake actuator assembly and brake booster with master cylinder assembly.

HINT:

As a visual check is very difficult, perform the check with the following procedure.

(1) Bleed the air from the brake system.

Click here

(2) Turn the power switch off.

(3) Disconnect the A34 brake pedal stroke sensor assembly connector.

(4) Select the Data List on the Techstream.

Click here

Chassis > ABS/VSC/TRAC > Data List

Tester Display	Measurement Item	Range	Normal Condition	Diagnostic Note
MT Voltage Value	MT voltage value	Min.: 0.00 V, Max.: 20.00 V	Pump motor off: 0.00 V Pump motor on: 12.00 V	-
Accumulator Pressure	Accumulator pressure output value	Min.: 0.00 MPa, Max.: 24.48 MPa	15.00 to 21.00 MPa (Pressure stable and pump motor stopped)	When brake fluid is stored in the accumulator: Accumulator pressure changes in accordance with volume of fluid stored in the accumulator

Tester Display

Measurement Item

Range

Normal Condition

Diagnostic Note

MT Voltage Value

MT voltage value

Min.: 0.00 V, Max.: 20.00 V

Pump motor off: 0.00 V

Pump motor on: 12.00 V

Accumulator Pressure

Accumulator pressure output value

Min.: 0.00 MPa, Max.: 24.48 MPa

15.00 to 21.00 MPa

(Pressure stable and pump motor stopped)

When brake fluid is stored in the accumulator: Accumulator pressure changes in accordance with volume of fluid stored in the accumulator

Chassis > ABS/VSC/TRAC > Data List

Tester Display
MT Voltage Value
Accumulator Pressure

(5) Depress the brake pedal several times to operate the pump motor, then wait until it stops.

(6) After the pump motor stops, wait for 30 seconds, then check the drop in the accumulator pressure sensor output value and the state of the pump motor.

Result	Proceed to
The drop in the accumulator pressure sensor output value is less than 2.50 MPa 30 seconds after the pump motor stops, and the pump motor does not operate within 30 seconds after the pump motor stops.	A
The drop in the accumulator pressure sensor output value is 2.50 MPa or more 30 seconds after the pump motor stops, or the pump motor operates within 30 seconds after the pump motor stops.	B

CHECK AND REPAIR BRAKE FLUID LEAKS OR ADD FLUID

2.	INSPECT BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY (BRAKE FLUID LEVEL WARNING SWITCH)

(a) Turn the power switch off.

*a	Component without harness connected (Brake Fluid Level Warning Switch (Brake Booster with Master Cylinder Assembly))

(b) Reconnect the A34 brake pedal stroke sensor assembly connector.

(d) Make sure that there is no looseness at the locking part and the connecting part of the connector.

OK:

The connector is securely connected.

(e) Disconnect the A4 brake fluid level warning switch (brake booster with master cylinder assembly) connector.

(f) Check both the connector case and the terminals for deformation and corrosion.

OK:

No deformation or corrosion.

(g) Measure the resistance according to the value(s) in the table below.

HINT:

A float is located inside the brake master cylinder reservoir assembly (brake booster with master cylinder assembly). Its position changes according to the level of brake fluid.

Standard Resistance:

Tester Connection	Condition	Specified Condition
2 (LBL) - 1 (GND)	Brake fluid level warning switch (brake booster with master cylinder assembly) off (float up)	1.84 to 2.16 kΩ
2 (LBL) - 1 (GND)	Brake fluid level warning switch (brake booster with master cylinder assembly) on (float down)	Below 1 Ω (Brake fluid level is low)

Tester Connection

Condition

Specified Condition

2 (LBL) - 1 (GND)

Brake fluid level warning switch (brake booster with master cylinder assembly) off (float up)

1.84 to 2.16 kΩ

2 (LBL) - 1 (GND)

Brake fluid level warning switch (brake booster with master cylinder assembly) on (float down)

Below 1 Ω

(Brake fluid level is low)

(h) If there are no problems after completing the preceding inspection, adjust the brake fluid to the MAX level with the power switch on (IG).

REPLACE BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY

3.	CHECK HARNESS AND CONNECTOR (BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY - BRAKE FLUID LEVEL WARNING SWITCH (BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY))

(a) Turn the power switch off.

(b) Make sure that there is no looseness at the locking part and the connecting part of the connector.

OK:

The connector is securely connected.

(d) Check both the connector case and the terminals for deformation and corrosion.

OK:

No deformation or corrosion.

(e) Measure the resistance according to the value(s) in the table below.

Standard Resistance:

Tester Connection	Condition	Specified Condition
A35-16 (LBL) - A4-2 (LBL)	Always	Below 1 Ω
A35-16 (LBL) or A4-2 (LBL) - Body ground	Always	10 kΩ or higher
A4-1 (GND) - Body ground	Always	Below 1 Ω

REPAIR OR REPLACE HARNESS OR CONNECTOR

4.	CHECK BRAKE DISC

(a) Reconnect the A35 skid control ECU (brake booster with master cylinder assembly) connector.

(b) Reconnect the A4 brake fluid level warning switch (brake booster with master cylinder assembly) connector.

(d) Perform a road test according to Freeze Frame Data or customer problem analysis. While driving, check for abnormal brake pedal vibration caused by brake discs that are worn or have excess runout.

OK:

Brake pedal does not vibrate during braking.

HINT:

An unevenly worn disc may vibrate the caliper pistons and cause fluctuations in brake line pressure, triggering a malfunction detection condition.
The brake pedal does not kick back due to caliper piston vibration during electronically controlled brake system control.
If the brake pedal stroke sensor assembly connector is disconnected, the fail-safe function will prohibit electronically controlled brake system control.
The Active Test does not prohibit electronically controlled brake system control when the vehicle is being driven, so disconnect the brake pedal stroke sensor assembly connector before continuing with inspection.
Uneven disc wear can be checked by measuring the disc thickness variation.
for Front Brake: Click here

for Rear Brake: Click here

REPLACE BRAKE DISC

5.	RECONFIRM DTC

(a) Turn the power switch off.

(b) Reconnect the A34 brake pedal stroke sensor assembly connector.

Click here

Chassis > ABS/VSC/TRAC > Clear DTCs

(d) Turn the power switch off.

(e) Turn the power switch on (READY).

(f) Perform a road test.

(g) Check if the same DTC is output.

Click here

Chassis > ABS/VSC/TRAC > Trouble Codes

Result	Proceed to
DTC C120F is not output.	A
DTC C120F is output.	B

USE SIMULATION METHOD TO CHECK

REPLACE BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY

Open Circuit in ABS Motor Relay Circuit (C146C,C146D)

DESCRIPTION

The ABS motor relay is built into the brake booster with master cylinder assembly.

During ABS, TRAC, VSC, brake hold, secondary collision brake or brake assist operation, the skid control ECU (brake booster with master cylinder assembly) turns on the ABS motor relay to run the pump motor in the brake actuator assembly.

When any DTC related to the ABS motor is stored, the IC built into the skid control ECU (brake booster with master cylinder assembly) operates in fail-safe mode.

When the supplied voltage to the BM terminal of the ABS motor relay is excessively low due to an auxiliary battery or charging circuit malfunction, DTC C146C and/or C146D is stored.

DTC No.	Detection Item	INF Code	DTC Detection Condition	Trouble Area	MIL	Note
C146C	Open Circuit in ABS Motor Relay Circuit	612	When operation of the ABS motor is requested, the ABS motor voltage is less than 7.6 V for 0.2 seconds or more.	Wire harness or connector Skid control ECU (brake booster with master cylinder assembly) Brake actuator assembly	Comes on	INF Code 612: SAE Code C052E ABS DTC
C146D	Short Circuit in ABS Motor Relay Circuit	613	A short in the ABS motor relay drive circuit is detected for 4 seconds or more.	Wire harness or connector Skid control ECU (brake booster with master cylinder assembly) Brake actuator assembly	Comes on	INF Code 613: SAE Code C052D (Case 1) ABS DTC

MONITOR DESCRIPTION

The skid control ECU (brake booster with master cylinder assembly) monitors the voltage of the ABS motor.

When the ABS motor relay is instructed to be on and the voltage of the ABS motor is within the range of an open circuit malfunction, or when the ABS motor is instructed to be off and the voltage of the ABS motor is within the range of a short circuit malfunction, an open circuit or short circuit is judged respectively and the MIL is illuminated and a DTC is stored.

MONITOR STRATEGY

Related DTCs	C052D (Case 1): ABS pump motor circuit high C052E: ABS pump motor open circuit
Required Sensors/Components(Main)	Brake actuator assembly
Required Sensors/Components(Related)	Skid control ECU (brake booster with master cylinder assembly) Brake actuator assembly
Frequency of Operation	Continuous
Duration	0.2 seconds: C052E 4 seconds: C052D (Case 1)
MIL Operation	Immediately
Sequence of Operation	None

TYPICAL ENABLING CONDITIONS

All

Monitor runs whenever the following DTCs are not stored

None

C052E

Either of the following conditions is met	A or B
A. Both of the following conditions are met	-
ABS pump motor voltage is 7.607 V or more experience	Not met
Command to ABS motor relay	On
B. All of the following conditions are met	-
ABS pump motor voltage is 7.607 V or more experience	Met
Command to ABS motor relay	On
Power supply for ABS motor	Higher than 9.13 V

C052D (Case 1)

Command to ABS motor relay

Off

TYPICAL MALFUNCTION THRESHOLDS

C052E

ABS pump motor voltage

Less than 7.607 V

C052D (Case 1)

ABS pump motor voltage

7.607 V or more, and less than 18.57 V

COMPONENT OPERATING RANGE

C052E

Both of the following conditions are met	-
Command to ABS motor relay	On
ABS pump motor voltage	7.607 V or more

C052D (Case 1)

ABS pump motor voltage

Less than 7.607 V, or 18.57 V or more

CONFIRMATION DRIVING PATTERN

Connect the Techstream to the DLC3.
Turn the power switch on (IG).
Turn the Techstream on.
Clear the DTCs (even if no DTCs are stored, perform the clear DTC procedure).
Turn the power switch off.
Turn the power switch on (IG).
Turn the Techstream on.
Wait 4 seconds.
Enter the following menus: Chassis / ABS/VSC/TRAC / Trouble Codes.
Read the DTCs.
HINT:
- If a DTC is output, the system is malfunctioning.
- If a DTC is not output, perform the following procedure.
If the DTCs are not output, perform a universal trip and check for permanent DTCs.
Click here

HINT:
- If a permanent DTC is output, the system is malfunctioning.
- If no permanent DTCs are output, the system is normal.

WIRING DIAGRAM

Refer to DTC C1427.

Click here

CAUTION / NOTICE / HINT

NOTICE:

After replacing the skid control ECU (brake booster with master cylinder assembly), perform linear solenoid valve offset learning, ABS holding solenoid valve learning, yaw rate and acceleration sensor zero point calibration and system information memorization after performing "Reset Memory".
Click here
Inspect the fuses for circuits related to this system before performing the following procedure.

HINT:

When DTCs C1241 and/or C1417 are output together with C146C and/or C146D, inspect and repair the trouble areas indicated by C1241 and/or C1417 first.

for C1241: Click here

for C1417: Click here

PROCEDURE

1.	CHECK HARNESS AND CONNECTOR (BM TERMINAL)

(a) Make sure that there is no looseness at the locking part and the connecting part of the connector.

OK:

The connector is securely connected.

*a	Front view of wire harness connector (to Skid Control ECU (Brake Booster with Master Cylinder Assembly))

(b) Disconnect the A35 skid control ECU (brake booster with master cylinder assembly) connector.

OK:

No deformation or corrosion.

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

Standard Voltage:

Tester Connection	Condition	Specified Condition
A35-41 (BM) - Body ground	Always	11 to 14 V

REPAIR OR REPLACE HARNESS OR CONNECTOR (BM CIRCUIT)

2.	CHECK HARNESS AND CONNECTOR (BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY - BRAKE ACTUATOR ASSEMBLY)

(a) Make sure that there is no looseness at the locking part and the connecting part of the connector.

OK:

The connector is securely connected.

(b) Disconnect the A39 brake actuator assembly connector.

OK:

No deformation or corrosion.

(d) Measure the resistance according to the value(s) in the table below.

Standard Resistance:

Tester Connection	Condition	Specified Condition
A35-40 (+BM) - A39-10 (+BM)	Always	Below 1 Ω
A35-40 (+BM) or A39-10 (+BM) - Body ground	Always	10 kΩ or higher

REPAIR OR REPLACE HARNESS OR CONNECTOR

3.	CHECK HARNESS AND CONNECTOR (GND TERMINAL)

(a) Measure the resistance according to the value(s) in the table below.

Standard Resistance:

Tester Connection	Condition	Specified Condition
A39-1 (MGND) - Body ground	Always	Below 1 Ω

*a	Front view of wire harness connector (to Brake Actuator Assembly)

REPAIR OR REPLACE HARNESS OR CONNECTOR (GND CIRCUIT)

4.	RECONFIRM DTC

(a) Reconnect the A35 skid control ECU (brake booster with master cylinder assembly) connector.

(b) Reconnect the A39 brake actuator assembly connector.

Click here

Chassis > ABS/VSC/TRAC > Clear DTCs

(d) Turn the power switch off.

(e) Turn the power switch on (READY).

(f) Perform a road test.

(g) Check if the same DTC is output.

Click here

Chassis > ABS/VSC/TRAC > Trouble Codes

Result	Proceed to
DTCs C146C and C146D are not output.	A
DTCs C146C and/or C146D are output.	B

HINT:

If a speed signal of 20 km/h (12 mph) or more is sent to the skid control ECU (brake booster with master cylinder assembly) with the power switch on (IG) and the stop light switch assembly off, the ECU performs self-diagnosis of the motor and solenoid circuits.
If the normal system code is output (no DTCs are output), slightly jiggle the connectors, wire harness, and fuses of the skid control ECU (brake booster with master cylinder assembly).
If any DTCs are output while jiggling a connector or wire harness from the skid control ECU (brake booster with master cylinder assembly), inspect and repair the connector or wire harness.
The DTCs were probably output due to a bad connection of the connector terminal.

USE SIMULATION METHOD TO CHECK

REPLACE BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY

EPB System Malfunction (C13AF). Reaction Force Pressure Sensor Zero Point Malfunction (C14B3). Servo Pressure Sensor Zero Point Malfunction (C14C3)

Open Circuit in ABS Solenoid Relay Circuit (C146E,C146F)

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