Toyota Avalon (XX50): Air Bag Circuit (C147D). Master Reservoir Level Malfunction (C1202). ECM Communication Circuit (C1203)

Toyota Avalon (XX50) 2019-2022 Service & Repair Manual / Brake / Brake Control / Dynamic Control Systems / Electronically Controlled Brake System(for Hv Model) / Air Bag Circuit (C147D). Master Reservoir Level Malfunction (C1202). ECM Communication Circuit (C1203)

Air Bag Circuit (C147D)

DESCRIPTION

The skid control ECU (brake booster with master cylinder assembly) receives the secondary collision brake control request signal from the airbag ECU assembly.

DTC No.	Detection Item	INF Code	DTC Detection Condition	Trouble Area	MIL	Note
C147D	Air Bag Circuit	451	An abnormal secondary collision brake control request signal is received 2 times or more when communication with the airbag ECU assembly is possible.	Airbag ECU assembly Skid control ECU (brake booster with master cylinder assembly)	Does not come on	Secondary collision brake DTC HINT: The DTC is cleared when the conditions return to normal.

DTC No.

Detection Item

INF Code

DTC Detection Condition

Trouble Area

MIL

Note

C147D

Air Bag Circuit

451

An abnormal secondary collision brake control request signal is received 2 times or more when communication with the airbag ECU assembly is possible.

Airbag ECU assembly
Skid control ECU (brake booster with master cylinder assembly)

Does not come on

Secondary collision brake DTC

HINT:

The DTC is cleared when the conditions return to 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

1.	CHECK DTC (AIRBAG SYSTEM)

(a) Check if airbag system DTCs are output.

Body Electrical > SRS Airbag > Trouble Codes

Result	Proceed to
DTCs are not output.	A
DTCs are output.	B

REPLACE BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY

INSPECT AIRBAG SYSTEM

Master Reservoir Level Malfunction (C1202)

DESCRIPTION

DTC No.	Detection Item	INF Code	DTC Detection Condition	Trouble Area	MIL	Note
C1202	Master Reservoir Level Malfunction	1126	Either of the following is detected: The brake fluid level warning switch signal circuit is open for a certain period of time. The reservoir level is low for a certain period of time.	Open or short in brake fluid level warning switch (brake booster with master cylinder assembly) Brake fluid leaks Open or short in wire harness Low brake fluid Skid control ECU (brake booster with master cylinder assembly)	Comes on	INF Code 1126: SAE Code C1202 Electronically controlled brake system DTC HINT: DTC C1202 (INF code 1126) is cleared when the conditions return to normal.

DTC No.

Detection Item

INF Code

DTC Detection Condition

Trouble Area

MIL

Note

C1202

Master Reservoir Level Malfunction

1126

Either of the following is detected:

The brake fluid level warning switch signal circuit is open for a certain period of time.
The reservoir level is low for a certain period of time.

Open or short in brake fluid level warning switch (brake booster with master cylinder assembly)
Brake fluid leaks
Open or short in wire harness
Low brake fluid
Skid control ECU (brake booster with master cylinder assembly)

Comes on

INF Code 1126: SAE Code C1202
Electronically controlled brake system DTC

HINT:

DTC C1202 (INF code 1126) is cleared when the conditions return to normal.

MONITOR DESCRIPTION

When the power switch is on (IG) and the fluid level warning switch (brake booster with master cylinder assembly) is on for a certain amount of time, the skid control ECU (brake booster with master cylinder assembly) judges that the brake fluid level in the reservoir is low and illuminates the MIL and stores this DTC.

MONITOR STRATEGY

Related DTCs	C1202: Brake master cylinder reservoir assembly level too low
Required Sensors/Components(Main)	Brake fluid level warning switch (brake booster with master cylinder assembly) Skid control ECU (brake booster with master cylinder assembly)
Required Sensors/Components(Related)	-
Frequency of Operation	Continuous
Duration	20 seconds
MIL Operation	Immediately
Sequence of Operation	None

TYPICAL ENABLING CONDITIONS

Monitor runs whenever the following DTCs are not stored	None
Power switch	On (IG)

TYPICAL MALFUNCTION THRESHOLDS

One of the following conditions is met	-
Brake fluid level warning switch state	On
Brake fluid level warning switch state	Open circuit
Serial communication with IC	Invalid

COMPONENT OPERATING RANGE

All of the following conditions are met	-
Power switch	On (IG)
Brake fluid level warning switch state	Off
Serial communication with IC	Valid

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 20 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

CAUTION / NOTICE / HINT

NOTICE:

Click here

PROCEDURE

CHECK DTC

(a) Clear the DTCs.

Click here

Chassis > ABS/VSC/TRAC > Clear DTCs

(b) Turn the power switch off.

(d) Check if the same DTC is output.

Click here

Chassis > ABS/VSC/TRAC > Trouble Codes

Result	Proceed to
DTC C1202 is output.	A
DTC C120F is output with DTC C1202.	B

GO TO DTC (C120F)

2.	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 master cylinder reservoir assembly (brake booster with master cylinder assembly), brake booster with master cylinder assembly, and wheel cylinders).

HINT:

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

Click here

(2) Check the thickness of the brake pad lining.

for Front Brake: Click here

for Rear Brake: Click here

HINT:

If the thickness is less than the standard, replace the brake pads with new ones.

(b) Check that there are no leaks from the connections between the brake booster pump 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

3.	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

4.	CHECK HARNESS AND CONNECTOR (BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY - BRAKE FLUID LEVEL WARNING SWITCH (BRAKE BOOSTER WITH MASTER CYLINDER 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 A35 skid control ECU (brake booster with master cylinder 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
A35-16 (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

5.	INSPECT BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY (SWITCH INPUT)

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

*a	Front view of wire harness connector (to Brake Fluid Level Warning Switch (Brake Booster with Master Cylinder Assembly))

(b) Turn the power switch on (IG).

Standard Voltage:

Tester Connection	Condition	Specified Condition
A4-2 (LBL) - Body ground	Power switch on (IG)	11 to 14 V

REPLACE BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY

6.	RECONFIRM DTC

(a) Turn the power switch off.

(b) Reconnect the A4 brake fluid level warning switch (brake booster with master cylinder 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 C1202 is not output.	A
DTC C1202 is output.	B

USE SIMULATION METHOD TO CHECK

REPLACE BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY

ECM Communication Circuit (C1203)

DESCRIPTION

DTC No.	Detection Item	INF Code	DTC Detection Condition	Trouble Area	MIL	Note
C1203	ECM Communication Circuit	1161	Either of the following is detected: Identification information sent from other ECUs does not match with the value stored when shipped from the factory. Identification information sent from other ECUs is not stored when shipped from the factory.	Other ECUs are not installed correctly Skid control ECU (brake booster with master cylinder assembly)	Comes on	INF Code 1161: SAE Code C124A Electronically controlled brake system DTC HINT: DTC C1203 (INF code 1161) is cleared when the conditions return to normal. This DTC is stored when incorrect identification information is detected and is not due to an ECM communication error.

DTC No.

Detection Item

INF Code

DTC Detection Condition

Trouble Area

MIL

Note

C1203

ECM Communication Circuit

1161

Either of the following is detected:

Identification information sent from other ECUs does not match with the value stored when shipped from the factory.
Identification information sent from other ECUs is not stored when shipped from the factory.

Other ECUs are not installed correctly
Skid control ECU (brake booster with master cylinder assembly)

Comes on

INF Code 1161: SAE Code C124A
Electronically controlled brake system DTC

HINT:

DTC C1203 (INF code 1161) is cleared when the conditions return to normal.
This DTC is stored when incorrect identification information is detected and is not due to an ECM communication error.

NOTICE:

DTC C1203 is output when an incorrect ECU is installed. If initialization is performed and learning occurs with an incorrect ECU installed, operations and functions will differ from those stored when the vehicle was shipped from the factory. Therefore, make sure that learning occurs properly.

MONITOR DESCRIPTION

When the vehicle is being driven, if the vehicle information, drive type or steering wheel position cannot be confirmed, the memorized data does not match or other related information cannot be stored such as when the ECU that was installed when the vehicle left the factory is changed or the EEPROM is malfunctioning, the skid control ECU (brake booster with master cylinder assembly) illuminates the MIL and stores this DTC.

MONITOR STRATEGY

Related DTCs	C124A: CAN communication identification signal
Required Sensors/Components(Main)	Skid control ECU (brake booster with master cylinder assembly)
Required Sensors/Components(Related)	Skid control ECU (brake booster with master cylinder assembly) Speed sensor
Frequency of Operation	Continuous
Duration	-
MIL Operation	Immediately
Sequence of Operation	None

TYPICAL ENABLING CONDITIONS

Monitor runs whenever the following DTCs are not stored	None
All of the following conditions are met	-
EEPROM read-in	Complete
IG1	On
Vehicle speed	40 km/h (25 mph) or more

TYPICAL MALFUNCTION THRESHOLDS

Both of the following conditions are met	A and B
A. Test Mode	Off
B. One of the following conditions is met	-
Grade info	Undetermined or different from a storage memory
Drive train info	Undetermined or different from a storage memory
Steering info	Undetermined or different from a storage memory
Car spec info	There is no write-in

COMPONENT OPERATING RANGE

All of the following conditions are met	-
EEPROM read-in	Complete
IG1	On
Test Mode	Off
Grade info	Decision and concordance from a storage memory
Drive train info	Decision and concordance from a storage memory
Steering info	Decision and concordance from a storage memory
Car spec info	There is write-in

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 (READY).
Turn the Techstream on.
Confirm that the vehicle is not in Test Mode and drive the vehicle at a speed of 40 km/h (25 mph) or more for 1 minute.
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:

Click here

PROCEDURE

1.	CHECK PART NUMBER

(a) Check that the proper hybrid vehicle control ECU and main body ECU (multiplex network body ECU) are installed.

OK:

Proper ECUs are installed.

(b) Check if the hybrid vehicle control ECU and main body ECU (multiplex network body ECU) were replaced before the DTC was recorded.

OK:

ECUs were not replaced.

Result	Proceed to
OK	A
NG (A proper hybrid vehicle control ECU is not installed and/or the hybrid vehicle control ECU was replaced.)	B
NG (A proper main body ECU (multiplex network body ECU) is not installed and/or the main body ECU (multiplex network body ECU) was replaced.)	C

REPLACE HYBRID VEHICLE CONTROL ECU

REPLACE MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU)

2.	PERFORM INITIALIZATION

(a) Perform linear solenoid valve offset learning, ABS holding solenoid valve learning and system information memorization.

Click here

Chassis > ABS/VSC/TRAC > Utility

Tester Display
ECB Utility

(b) Perform yaw rate and acceleration sensor zero point calibration.

Click here

Chassis > ABS/VSC/TRAC > Utility

Tester Display
Test Mode

HINT:

After installing a new skid control ECU (brake booster with master cylinder assembly), before performing linear solenoid valve offset learning, ABS holding solenoid valve learning, yaw rate and acceleration sensor zero point calibration and system information memorization, DTC C1203 will be output.
If linear solenoid valve offset learning, ABS holding solenoid valve learning, yaw rate and acceleration sensor zero point calibration and system information memorization are not performed, DTC C1203 will be output after the data stored in the skid control ECU (brake booster with master cylinder assembly) is cleared by performing "Reset Memory" using Techstream.

3.	RECONFIRM DTC

(a) Clear the DTCs.

Click here

Chassis > ABS/VSC/TRAC > Clear DTCs

(b) Turn the power switch off.

(d) Check if the same DTC is output.

Click here

Chassis > ABS/VSC/TRAC > Trouble Codes

Result	Proceed to
DTC C1203 is output.	A
DTC C1203 is not output.	B

REPLACE BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY

END

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

Zero Point Calibration of Yaw Rate Sensor undone (C1210,C1336). SLA Linear Solenoid (C1211,C1212,C1225,C1226). Hydraulic Control System Malfunction (C1214)

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