Toyota Avalon (XX50): Open in Stop Switch Circuit (C1425,P0573)

DESCRIPTION

The skid control ECU (brake booster with master cylinder assembly) detects the brake operating conditions through a signal transmitted by the stop light switch assembly.

The skid control ECU incorporates a circuit to detect an open circuit. This DTC is output when an open circuit is detected in the stop light signal input line.

DTC No.	Detection Item	INF Code	DTC Detection Condition	Trouble Area	MIL	Note
C1425	Open in Stop Switch Circuit	231	An open stop light switch circuit continues for 10 seconds or more.	Wire harness or connector Stop light switch assembly Skid control ECU (brake booster with master cylinder assembly)	Comes on	INF Code 231: SAE Code P0572 Electronically controlled brake system DTC
P0573	Brake Switch "A" Circuit High	-	The stop light switch assembly is stuck 10 times or more.	Wire harness or connector Stop light switch assembly Skid control ECU (brake booster with master cylinder assembly)	Comes on	-

MONITOR DESCRIPTION

When the voltage at terminal STP is outside the range of that when the stop light switch assembly is on or the range of that when the stop light switch assembly is off for a certain amount of time, the skid control ECU (brake booster with master cylinder assembly) judges that there is an open in the stop light switch assembly circuit and illuminates the MIL and stores a DTC.

Also, if the voltage at terminal STP is always within the range of that when the stop light switch assembly is on after the vehicle is driven at a certain speed or more and stopped a specific number of times, the skid control ECU (brake booster with master cylinder assembly) judges that the stop light switch assembly is stuck on and illuminates the MIL and stores a DTC.

MONITOR STRATEGY

Related DTCs	P0572: Stop light switch assembly open circuit P0573: Stop light switch assembly circuit high
Required Sensors/Components(Main)	Stop light switch assembly Speed sensor
Required Sensors/Components(Related)	Skid control ECU (brake booster with master cylinder assembly)
Frequency of Operation	Continuous
Duration	10 seconds: P0572 10 times: P0573
MIL Operation	Immediately
Sequence of Operation	None

TYPICAL ENABLING CONDITIONS

All

Monitor runs whenever the following DTCs are not stored

None

P0572

Both of the following conditions are met	-
Serial communication with high side IC	Valid
IG1 voltage	Higher than 9.54 V

P0573

Serial communication with high side IC

Valid

TYPICAL MALFUNCTION THRESHOLDS

P0572

Stop light switch assembly voltage

Higher than 2.75 V, and less than 4.25 V

P0573

Stop light switch assembly voltage when decelerating vehicle from 30 km/h (19 mph) or more to 3 km/h (2 mph)

4.25 V or more

COMPONENT OPERATING RANGE

P0572

All of the following conditions are met	-
Stop light switch assembly on experience	On
Stop light switch assembly off experience	On
Stop light switch assembly voltage	2.75 V or less, or 4.25 V or more

P0573

Both of the following conditions are met	-
Serial communication with high side IC	Valid
Stop light switch assembly voltage	2.75 V or less

CONFIRMATION DRIVING PATTERN

1. Connect the Techstream to the DLC3.
2. Turn the power switch on (IG).
3. Turn the Techstream on.
4. Clear the DTCs (even if no DTCs are stored, perform the clear DTC procedure).
5. Turn the power switch off.
6. Turn the power switch on (READY).
7. Turn the Techstream on.
8. Decelerate the vehicle from a speed of 30 km/h (19 mph) or more to 3 km/h (2 mph) 10 times or more.
9. Enter the following menus: Chassis / ABS/VSC/TRAC / Trouble Codes.
10. Read the DTCs.

    HINT:

    • If a DTC is output, the system is malfunctioning.
    • If a DTC is not output, perform the following procedure.
11. 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

1.	CHECK STOP LIGHT OPERATION

(a) Check that the stop lights come on when the brake pedal is depressed and go off when the brake pedal is released.

OK:

Condition	Illumination Condition
Brake pedal depressed.	On
Brake pedal released.	Off

NG

GO TO STEP 5

OK

2.	READ VALUE USING TECHSTREAM (STOP LIGHT SWITCH ASSEMBLY)

(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
Stop Light SW	Stop light switch assembly	ON or OFF	ON: Brake pedal depressed OFF: Brake pedal released	-

Chassis > ABS/VSC/TRAC > Data List

Tester Display
Stop Light SW

(b) Check that the stop light switch assembly display observed on the Techstream changes according to brake pedal operation.

OK:

The Techstream displays on or off according to brake pedal operation.

NG

GO TO STEP 4

OK

3.	RECONFIRM DTC

(a) Clear the DTCs.

Click here

Chassis > ABS/VSC/TRAC > Clear DTCs

(b) Turn the power switch off.

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

(d) Perform a road test.

(e) Check if the same DTC is output.

Click here

Chassis > ABS/VSC/TRAC > Trouble Codes

Result	Proceed to
DTCs C1425 and P0573 are not output.	A
DTCs C1425 and/or P0573 are output.	B

A

USE SIMULATION METHOD TO CHECK

B

REPLACE BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY

4.	CHECK HARNESS AND CONNECTOR (STP 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.

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

(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
A35-12 (STP) - Body ground	Stop light switch assembly on (Brake pedal depressed)	11 to 14 V
A35-12 (STP) - Body ground	Stop light switch assembly off (Brake pedal released)	1.5 V or less

OK

REPLACE BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR (STP CIRCUIT)

5.	INSPECT STOP LIGHT SWITCH ASSEMBLY

(a) Check the stop light switch assembly.

Click here

OK:

The stop light switch assembly is normal.

NG

REPLACE STOP LIGHT SWITCH ASSEMBLY

OK

6.	CHECK HARNESS AND CONNECTOR (STP 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.

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

(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
A35-12 (STP) - Body ground	Stop light switch assembly on (Brake pedal depressed)	11 to 14 V
A35-12 (STP) - Body ground	Stop light switch assembly off (Brake pedal released)	1.5 V or less

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR (STP CIRCUIT)

OK

7.	RECONFIRM DTC

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

(b) Clear the DTCs.

Click here

Chassis > ABS/VSC/TRAC > Clear DTCs

(c) Turn the power switch off.

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

(e) Perform a road test.

(f) Check if the same DTC is output.

Click here

Chassis > ABS/VSC/TRAC > Trouble Codes

Result	Proceed to
DTCs C1425 and P0573 are not output.	A
DTCs C1425 and/or P0573 are output.	B

HINT:

If the lighting system is normal but the DTC is still output, replace the skid control ECU (brake booster with master cylinder assembly).

Click here

A

USE SIMULATION METHOD TO CHECK

B

INSPECT LIGHTING SYSTEM (STOP LIGHT CIRCUIT)