BRAKE CONTROL / DYNAMIC CONTROL SYSTEMS: ELECTRONICALLY CONTROLLED BRAKE SYSTEM (for HV Model): C1252,C1253; Brake Booster Pump Motor on Time Abnormally Long; 2020 - 2022 MY Corolla Corolla HV [01/2019

Last Modified: 07-31-2024	6.11:8.1.0	Doc ID: RM100000001G78R
Model Year Start: 2020	Model: Corolla	Prod Date Range: [01/2019 - 09/2022]
Title: BRAKE CONTROL / DYNAMIC CONTROL SYSTEMS: ELECTRONICALLY CONTROLLED BRAKE SYSTEM (for HV Model): C1252,C1253; Brake Booster Pump Motor on Time Abnormally Long; 2020 - 2022 MY Corolla Corolla HV [01/2019 - 09/2022]

DTC

C1252

Brake Booster Pump Motor on Time Abnormally Long

DTC

C1253

Pump Motor Relay

DESCRIPTION

The skid control ECU (brake booster with master cylinder assembly) detects decreases in the accumulator pressure according to the data from the accumulator pressure sensor, and then starts and stops the pump motor by operating the motor relay.

DTC No.

Detection Item

INF Code

DTC Detection Condition

Trouble Area

MIL

Note

C1252

Brake Booster Pump Motor on Time Abnormally Long

311

The pump motor is operating continuously for 178 seconds or more. (When the relay is malfunctioning for 98 seconds or more.)

Short in pump motor circuit or pump motor monitor circuit
Motor relay stuck
Accumulator pressure sensor malfunction
Skid control ECU (brake booster with master cylinder assembly)

Comes on

INF Code 311: SAE Code C0594
Electronically controlled brake system DTC

C1253

Pump Motor Relay

321

322

327

328

INF Code: 321, 327, 328
- An open is detected in the motor relay drive circuit for 0.2 seconds or more.
INF Code: 322
- A short is detected in the motor relay drive circuit for 2 seconds or more.

INF Code: 321, 327, 328
- Open in pump motor circuit or pump motor monitor circuit
- Skid control ECU (brake booster with master cylinder assembly)
INF Code: 322
- Short in pump motor circuit or pump motor monitor circuit
- Skid control ECU (brake booster with master cylinder assembly)

Comes on

(When only SAE code C121D or SAE code C121E is stored)

INF Code 321: SAE Code C121D
INF Code 322: SAE Code C121E
Electronically controlled brake system DTC

MONITOR DESCRIPTION

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

When the pump motor relay is instructed to be on and the voltage of the pump motor is within the range of an open circuit malfunction (voltage value is practically equal to that when off), or when the pump motor is instructed to be off and the voltage of the pump motor is within the range of a short circuit malfunction (voltage value is practically equal to that when on), an open circuit or short circuit is judged respectively and the MIL is illuminated and stores a DTC.

Furthermore, when the voltage of the pump motor is practically equal to that when on for a long period of time, the skid control ECU (brake booster with master cylinder assembly) judges that the pump motor is operating for an abnormally long time and illuminates the MIL and stores a DTC.

MONITOR STRATEGY

Related DTCs	C0594: Pump motor performance C121D: Pump motor open circuit C121E: Pump motor circuit high
Required Sensors/Components(Main)	Brake booster pump assembly
Required Sensors/Components(Related)	Skid control ECU (brake booster with master cylinder assembly) Brake booster pump assembly Brake actuator (brake booster with master cylinder assembly)
Frequency of Operation	Continuous
Duration	0.2 seconds: C121D 2 seconds: C121E 98 seconds: C0594 (Case 1) 178 seconds: C0594 (Case 2)
MIL Operation	Immediately
Sequence of Operation	None

TYPICAL ENABLING CONDITIONS

C0594 (Case 1)

Monitor runs whenever the following DTCs are not stored	None
Both of the following conditions are met	A and B
A. Serial communication with high side IC	Valid
B. One of the following conditions is met	a, b or c
a. Pump motor circuit fail (C121D)	Detected
b. Pump motor circuit fail (C121E)	Detected
c. Both of the following conditions are met	-
Accumulator pressure sensor	Valid
Accumulator pressure	Higher than 19.88 MPa (202.7 kgf/cm², 2884 psi)

C0594 (Case 2)

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

C121D

Monitor runs whenever the following DTCs are not stored	None
Both of the following conditions are met	A and B
A. Serial communication with high side IC	Valid
B. Either of the following conditions is met	a or b
a. Command to pump motor relay	On
b. Both of the following conditions are met	-
Command to pump motor relay from hardware	On
Serial communication with low side IC	Valid

C121E

Monitor runs whenever the following DTCs are not stored	None
All of the following conditions are met	-
Serial communication with high side IC	Valid
Serial communication with low side IC	Valid
Command to pump motor relay	Off
Command to pump motor relay from hardware	Off

TYPICAL MALFUNCTION THRESHOLDS

C0594 (Case 1), C0594 (Case 2) and C121E

Pump motor voltage

Higher than 6 V

C121D

Pump motor voltage

Less than 6 V

COMPONENT OPERATING RANGE

C0594

Both of the following conditions are met	-
Prohibit pump motor operating from microcomputer	Off
Pump motor voltage	Less than 6 V

C121D

All of the following conditions are met	A, B and C
A. Serial communication with high side IC	Valid
B. Either of the following conditions is met	a or b
a. Command to pump motor relay	On
b. Both of the following conditions are met	-
Command to pump motor relay from hardware	On
Serial communication with low side IC	Valid
C. Pump motor voltage	Higher than 6 V

C121E

Both of the following conditions are met	-
Serial communication with high side IC	Valid
Pump motor voltage	Less than 6 V

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.
Depress the brake pedal several times until the pump motor operates.
Wait 3 minutes.
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

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.

PROCEDURE

CHECK DTC

(a) Check the DTCs that are output.

Click here

Chassis > ABS/VSC/TRAC > Trouble Codes

Result	Proceed to
DTCs C1252 and/or C1253 are output.	A
DTCs C1241 and/or C1242 are output with DTCs C1252 and/or C1253.	B

REPAIR CIRCUITS INDICATED BY OUTPUT DTCS

2.	READ VALUE USING TECHSTREAM (MOTOR RELAY 1 AND MOTOR RELAY 2)

(a) Select the Data List on the Techstream.

Click here

Chassis > ABS/VSC/TRAC > Data List

Tester Display

Measurement Item

Range

Normal Condition

Diagnostic Note

ECB Motor Relay

Motor relay 1 operation request

ON or OFF

ON: Relay on

OFF: Relay off

ECB: Electronically Controlled Brake System

ECB Motor Relay2

Motor relay 2 operation request

ON or OFF

ON: Relay on

OFF: Relay off

ECB: Electronically Controlled Brake System

Chassis > ABS/VSC/TRAC > Data List

Tester Display
ECB Motor Relay
ECB Motor Relay2

(b) Depress the brake pedal several times and check the operation status of the motor relay 1 and motor relay 2.

HINT:

Depressing the brake pedal several times drops the accumulator pressure and operates the pump motor.

Result	Proceed to
The motor relay 1 and motor relay 2 in the Data List turns on or off by depressing the brake pedal several times.	A
The status of motor relay 1 and motor relay 2 in the Data List does not change even after depressing the brake pedal several times.	B

GO TO STEP 8

3.	INSPECT BRAKE BOOSTER PUMP ASSEMBLY

(a) Turn the power switch off.

*a	Component without harness connected (Brake Booster Pump Assembly)

(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
2 (BM1) - 4 (GND1)	Always	10 Ω or less
1 (BM2) - 3 (GND2)	Always	10 Ω or less
2 (BM1) - 1 (BM2)	Always	Below 1 Ω
4 (GND1) - 3 (GND2)	Always	Below 1 Ω

REPLACE BRAKE BOOSTER PUMP ASSEMBLY

4.	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
A10-4 (GND1) - Body ground	1 minute or more after disconnecting the cable from the negative (-) auxiliary battery terminal	Below 1 Ω
A10-3 (GND2) - Body ground	1 minute or more after disconnecting the cable from the negative (-) auxiliary battery terminal	Below 1 Ω

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

REPAIR OR REPLACE HARNESS OR CONNECTOR (GND CIRCUIT)

5.	READ VALUE USING TECHSTREAM (ACCUMULATOR PRESSURE)

(a) Reconnect the A10 brake booster pump assembly connector.

(b) Disconnect the A9 brake pedal stroke sensor assembly connector.

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

Chassis > ABS/VSC/TRAC > Data List

Tester Display
MT Voltage Value
Accumulator Pressure

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

(e) 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.

HINT:

This inspection checks whether an accumulator pressure sensor malfunction, internal brake actuator (brake booster with master cylinder assembly) leak or prolonged operation due to detection of low pressure caused by accumulator deterioration, caused the DTC to be stored.
If the brake fluid level in the brake master cylinder reservoir assembly (brake booster with master cylinder assembly) drops, an external brake fluid leak is suspected.

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

GO TO STEP 7

6.	RECONFIRM DTC

(a) Turn the power switch off.

(b) Reconnect the A9 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 (IG).

(f) Check if the same DTC is output.

Click here

Chassis > ABS/VSC/TRAC > Trouble Codes

Result	Proceed to
DTCs C1252 and C1253 are not output.	A
DTCs C1252 and/or C1253 are output.	B

USE SIMULATION METHOD TO CHECK

REPLACE BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY

7.	READ VALUE USING TECHSTREAM (SERVO PRESSURE)

(a) Turn the power switch off.

(b) Reconnect the A9 brake pedal stroke sensor assembly connector.

Click here

Chassis > ABS/VSC/TRAC > Active Test

Tester Display	Measurement Item	Control Range	Diagnostic Note
ECB Solenoid (SLR)	Linear solenoid reduction valve (SLR)	Solenoid ON/OFF	ECB: Electronically Controlled Brake System

Chassis > ABS/VSC/TRAC > Data List

Tester Display	Measurement Item	Range	Normal Condition	Diagnostic Note
Servo Pressure	Pressure value of servo	Min.: 0.00 MPa, Max.: 24.48 MPa	Brake pedal released: 0.00 to 2.10 MPa	Brake pedal is being depressed: Changes in proportion to the depression force of the brake pedal

Chassis > ABS/VSC/TRAC > Active Test

Active Test Display
ECB Solenoid (SLR)

Data List Display
Servo Pressure

(d) Perform the Active Test and operate the linear solenoid (SLR) in the brake actuator (brake booster with master cylinder assembly).

(e) Check that the servo pressure output value does not increase when performing the Active Test.

OK:

The servo pressure output value does not increase when performing the Active Test.

HINT:

If the servo pressure output value increases, an internal brake fluid leak in the brake actuator (brake booster with master cylinder assembly) is suspected.

Result	Proceed to
The servo pressure output value increases.	A
The servo pressure output value does not increase.	B

REPLACE BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY

REPLACE BRAKE BOOSTER PUMP ASSEMBLY

8.	CHECK HARNESS AND CONNECTOR (MRI TERMINAL)

(a) Turn the power switch off.

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

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

Standard Voltage:

Tester Connection	Condition	Specified Condition
A48-2 (MRI1) - Body ground	Always	11 to 14 V
A48-28 (MRI2) - Body ground	Always	11 to 14 V

REPAIR OR REPLACE HARNESS OR CONNECTOR (MRI CIRCUIT)

9.	CHECK HARNESS AND CONNECTOR (BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY - BRAKE BOOSTER PUMP 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 A10 brake booster pump 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
A48-1 (MRO1) - A10-2 (BM1)	Always	Below 1 Ω
A48-1 (MRO1) or A10-2 (BM1) - Body ground	Always	10 kΩ or higher
A48-27 (MRO2) - A10-1 (BM2)	Always	Below 1 Ω
A48-27 (MRO2) or A10-1 (BM2) - Body ground	Always	10 kΩ or higher

REPLACE BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY

REPAIR OR REPLACE HARNESS OR CONNECTOR