Toyota Avalon (XX50): System Diagram. Terminals Of Ecu. Test Mode Procedure

Toyota Avalon (XX50) 2019-2022 Service & Repair Manual / Brake / Brake Control / Dynamic Control Systems / Electronically Controlled Brake System(for Gasoline Model) / System Diagram. Terminals Of Ecu. Test Mode Procedure

System Diagram

SYSTEM DIAGRAM

Transmitting ECU (Transmitter)	Receiving ECU	Signal	Communication Method
Skid control ECU (brake actuator assembly)	Steering angle sensor	Steering angle sensor request signal	CAN communication line
Steering angle sensor	Skid control ECU (brake actuator assembly)	Steering angle sensor signal	CAN communication line
Skid control ECU (brake actuator assembly)	Yaw rate and acceleration sensor (airbag sensor assembly)	Yaw rate and acceleration request signal	CAN communication line
Yaw rate and acceleration sensor (airbag sensor assembly)	Skid control ECU (brake actuator assembly)	Yaw rate and acceleration signal	CAN communication line
Skid control ECU (brake actuator assembly)	ECM	Wheel speed signal VSC data signal	CAN communication line
ECM	Skid control ECU (brake actuator assembly)	Shift position signal Throttle position signal Engine speed signal	CAN communication line
Skid control ECU (brake actuator assembly)	Power steering ECU (rack and pinion power steering gear assembly)	Wheel speed signal VSC data signal	CAN communication line
Main body ECU (multiplex network body ECU)	Skid control ECU (brake actuator assembly)	Driver seat belt buckle switch signal Driver side courtesy switch signal	CAN communication line
Skid control ECU (brake actuator assembly)	Combination meter assembly	ABS warning light signal Brake system warning light (red indicator) signal VSC OFF indicator light signal Multi-information display (Traction Control Turned Off) signal Multi-information display (Secondary Collision Brake System Malfunction) signal Multi-information display (Brake hold system malfunction) signal Slip indicator light signal Vehicle speed signal Brake hold standby indicator light signal Brake hold operated indicator light signal	CAN communication line
Airbag sensor assembly	Skid control ECU (brake actuator assembly)	Secondary collision brake request signal	CAN communication line

Terminals Of Ecu

TERMINALS OF ECU

TERMINALS OF ECU

Component without harness connected

(Skid Control ECU (Brake Actuator Assembly))

Terminal No. (Symbol)	Terminal Description
1 (+BM)	ABS motor relay power supply
2	-
3	-
4	-
5 (CANH)	CAN communication line H
6 (CSW)	VSC OFF switch input
7 (FL-)	Front wheel speed LH (-) signal input
8	-
9	-
10 (STPO)	Stop light control relay (stop light switch assembly) output
11	-
12	-
13	-
14 (GND2)	Pump motor ground
15	-
16	-
17	-
18	-
19 (CANL)	CAN communication line L
20	-
21 (FR+)	Front wheel speed RH (+) signal input
22 (RR+)	Rear wheel speed RH (+) signal input
23 (RL-)	Rear wheel speed LH (-) signal input
24 (FL+)	Front wheel speed LH (+) signal input
25	-
26 (FR-)	Front wheel speed RH (-) signal input
27	-
28	-
29	-
30 (+BS)	ABS solenoid relay power supply
31	-
32	-
33	-
34 (SP1)	Speed signal output for speedometer
35	-
36 (IG1)	IG1 power source input
37 (RR-)	Rear wheel speed RH (-) signal input
38	-
39 (RL+)	Rear wheel speed LH (+) signal input
40	-
41	-
42 (STP)	Stop light switch assembly input
43 (HZRI)	Brake hold switch (electric parking brake switch assembly) input
44 (STP2)	Stop light control relay (stop light switch assembly) input
45	-
46 (GND1)	Skid control ECU (brake actuator assembly) ground

TERMINAL INSPECTION

(a) Disconnect the connector and measure the voltage and resistance on the wire harness side.

Front view of wire harness connector (to Skid Control ECU (Brake Actuator Assembly))

HINT:

The voltage cannot be measured with the connector connected to the skid control ECU (brake actuator assembly) because the connector is watertight.

Standard

Terminal No. (Symbol)	Wiring Color	Terminal Description	Condition	Specified Condition
A28-1 (+BM) - Body ground	B - Body ground	ABS motor relay power supply	Always	11 to 14 V
A28-6 (CSW) - Body ground	P - Body ground	VSC OFF switch input	VSC OFF switch on → off (Pressed → not pressed)	Below 1 Ω → 10 kΩ or higher
A28-10 (STPO) - Body ground	L - Body ground	Stop light control relay (stop light switch assembly) output	Always	11 to 14 V
A28-14 (GND2) - Body ground	W-B - Body ground	Pump motor ground	Always	Below 1 Ω
A28-30 (+BS) - Body ground	G - Body ground	ABS solenoid relay power supply	Always	11 to 14 V
A28-36 (IG1) - Body ground	B - Body ground	IG1 power source input	Engine switch on (IG)	11 to 14 V
A28-42 (STP) - Body ground	GR - Body ground	Stop light switch assembly input	Stop light switch assembly on → off (Brake pedal depressed → released)	(+BS x 0.85) to 14 V* → Below 1.5 V
A28-43 (HZRI) - Body ground	LG - Body ground	Brake hold switch (electric parking brake switch assembly) input	Brake hold switch (electric parking brake switch assembly) on → off (Pressed → not pressed)	Below 1 Ω → 10 kΩ or higher
A28-44 (STP2) - Body ground	R - Body ground	Stop light control relay (stop light switch assembly) input	Stop light switch assembly on → off (Brake pedal depressed → released)	(+BS x 0.85) to 14 V* → Below 1.5 V
A28-46 (GND1) - Body ground	W-B - Body ground	Skid control ECU (brake actuator assembly) ground	Always	Below 1 Ω

HINT:

*: The minimum voltage value varies depending on the +BS terminal voltage value. The minimum voltage is 85% or more of the +BS terminal voltage.

Test Mode Procedure

TEST MODE PROCEDURE

WARNING LIGHT AND INDICATOR LIGHT INITIAL CHECK

(a) When the engine switch is turned on (IG), check that the ABS warning light, brake system warning light (red indicator), VSC OFF indicator light, brake hold standby indicator light, brake hold operated indicator light and slip indicator light come on for approximately 3 seconds.

HINT:

When the brake fluid level is low or the vacuum inside the brake booster decreases, the brake system warning light (red indicator) comes on.
If the skid control ECU (brake actuator assembly) stores a DTC, the ABS warning light, brake system warning light (red indicator) and slip indicator lights will come on.
If a DTC is stored by the skid control ECU (brake actuator assembly) and the following conditions are met when the brake hold switch (electric parking brake switch assembly) is pressed, the brake hold operated indicator light blinks.
- Vehicle Conditions:
  1. The driver door is closed.
  2. The driver seat belt is fastened.
If any of the indicators remains on or does not come on, proceed to troubleshooting for the light circuits listed below.

Trouble Area	See Procedure
ABS warning light circuit (Remains on)
ABS warning light circuit (Does not come on)
Brake system warning light (red indicator) circuit (Remains on)
Brake system warning light (red indicator) circuit (Does not come on)
VSC OFF indicator light circuit (Remains on)
VSC OFF indicator light circuit (Does not come on)
Slip indicator light circuit (Remains on)
Slip indicator light circuit (Does not come on)
Brake hold standby indicator light circuit
Brake hold operated indicator light circuit

SENSOR CHECK USING TEST MODE (SIGNAL CHECK) (When Using TECHSTREAM)

NOTICE:

Perform Test Mode (Signal Check) with the vehicle stopped.

HINT:

DTCs are stored if any malfunctions are detected during the check of each sensor.
When entering Test Mode (Signal Check), the skid control ECU (brake actuator assembly) communicates with the driving support ECU assembly to judge whether the vehicle is equipped with the pre-collision system. Therefore, do not exit Test Mode (Signal Check) within 5 seconds of entering Test Mode (Signal Check).

(a) Procedure to enter Test Mode (Signal Check)

(1) Turn the engine switch off.

(2) Check that the steering wheel is centered.

(3) Check that the shift lever is in P.

(4) Connect the Techstream to the DLC3.

(5) Turn the engine switch on (IG).

(6) Turn the Techstream on.

(7) Switch the skid control ECU (brake actuator assembly) to Test Mode (Signal Check) using the Techstream. Enter the following menus: Chassis / ABS/VSC/TRAC/EPB / Utility / Signal Check.

Chassis > ABS/VSC/TRAC/EPB > Utility

Tester Display
Signal Check

HINT:

Do not exit Test Mode (Signal Check) within 5 seconds of entering Test Mode (Signal Check). If Test Mode (Signal Check) is exited within 5 seconds of entering Test Mode (Signal Check), DTC U1104 may be stored. If DTC U1104 is output after exiting Test Mode (Signal Check), enter Test Mode (Signal Check) again, wait at least 5 seconds, then recheck for DTCs.

(8) Check that the ABS warning and slip indicator lights come on for several seconds and the ABS warning, slip indicator and parking brake indicator lights blink in the Test Mode pattern.

HINT:

If the ABS warning, slip indicator and parking brake indicator lights do not blink, inspect the ABS warning, slip indicator and parking brake indicator light circuits.
While the parking brake is engaged, the parking brake indicator light illuminates but does not blink in the Test Mode pattern.

(9) Check the ABS sensors.

HINT:

Check that the ABS warning light is blinking in the Test Mode pattern before performing the following ABS sensor checks.

(b) Speed Sensor Check

(1) Drive the vehicle straight-ahead.

Accelerate the vehicle to a speed of 47 to 55 km/h (29 to 34 mph) for several seconds.

NOTICE:

If the vehicle is driven at 80 km/h or more after the ABS warning light turns off, the speed sensor check will be performed again. In this situation, the ABS warning light will start blinking again.

HINT:

The speed sensor check may not complete if wheelspin occurs.
The speed sensor check may not complete if the speed sensor check is started while turning the steering wheel.

(2) Check that the ABS warning light goes off.

HINT:

The ABS warning light goes off when the sensor check has completed.
The ABS warning light comes on immediately after a malfunction has been detected during the speed sensor check.

(3) Stop the vehicle.

NOTICE:

If the sensor check has not completed, the ABS warning light will blink while the vehicle is being driven and the ABS will not operate.

HINT:

When the sensor check has completed, the ABS warning light goes off while the vehicle is being driven, and blinks in the Test Mode pattern while the vehicle is stopped.

(1) Press the VSC OFF switch.

(2) Check that the VSC OFF indicator light comes on.

(3) Press the VSC OFF switch again.

(d) Brake Hold Switch (Electric Parking Brake Switch Assembly) Check

(1) Make sure the following conditions are met:

The driver door is closed.
The driver seat belt is fastened.

(2) Press the brake hold switch (electric parking brake switch assembly).

(3) Check that the brake hold standby indicator light comes on.

(4) Press the brake hold switch (electric parking brake switch assembly) again.

(e) End of Sensor Check

(1) If the sensor checks have completed, the ABS warning light blinks in the Test Mode pattern when the vehicle is stopped and the ABS warning light goes off while the vehicle is being driven.

NOTICE:

If the sensor checks have not completed, the ABS warning light will blink while the vehicle is being driven and the ABS will not operate.

(f) End of Test Mode (Signal Check)

(1) Turn the engine switch off and disconnect the Techstream.

(g) Test Mode (Signal Check) Inspection Item Chart

Item Name	Range	Judgment Description	Trouble Area
Output Signal of Front Speed Sensor RH	Incomplete/complete	Check for foreign matter Check the gap between the sensor and rotor	Open or short in speed sensor Open or short in wire harness Improperly connected connector, deformation or corrosion of terminals Sensor installation Front speed sensor rotor RH (front axle hub sub-assembly RH)
Output Signal of Front Speed Sensor LH	Incomplete/complete	Check for foreign matter Check the gap between the sensor and rotor	Open or short in speed sensor Open or short in wire harness Improperly connected connector, deformation or corrosion of terminals Sensor installation Front speed sensor rotor LH (front axle hub sub-assembly LH)
Output Signal of Rear Speed Sensor RH	Incomplete/complete	Check for foreign matter Check the gap between the sensor and rotor	Open or short in speed sensor Open or short in wire harness Improperly connected connector, deformation or corrosion of terminals Sensor installation Rear speed sensor rotor RH (rear axle hub and bearing assembly RH)
Output Signal of Rear Speed Sensor LH	Incomplete/complete	Check for foreign matter Check the gap between the sensor and rotor	Open or short in speed sensor Open or short in wire harness Improperly connected connector, deformation or corrosion of terminals Sensor installation Rear speed sensor rotor LH (rear axle hub and bearing assembly LH)
Change in Output Signal of Front Speed Sensor RH	Incomplete/complete	Check the stability of the sensor output waveform	Front speed sensor RH Front speed sensor rotor RH (front axle hub sub-assembly RH)
Change in Output Signal of Front Speed Sensor LH	Incomplete/complete	Check the stability of the sensor output waveform	Front speed sensor LH Front speed sensor rotor LH (front axle hub sub-assembly LH)
Change in Output Signal of Rear Speed Sensor RH	Incomplete/complete	Check the stability of the sensor output waveform	Rear speed sensor RH (rear axle hub and bearing assembly RH) Rear speed sensor rotor RH (rear axle hub and bearing assembly RH)
Change in Output Signal of Rear Speed Sensor LH	Incomplete/complete	Check the stability of the sensor output waveform	Rear speed sensor LH (rear axle hub and bearing assembly LH) Rear speed sensor rotor LH (rear axle hub and bearing assembly LH)

Problem Symptoms Table. Slip Indicator Light does not Come ON. Slip Indicator Light Remains ON

TRAC does not Operate. Vehicle Control History. VSC does not Operate or VSC does not Operate Correctly

See More:

Toyota Avalon (XX50) 2019-2022 Service & Repair Manual > Sfi System: Dtc Check / Clear. ECM Power Source Circuit. Engine Difficult to Start
Dtc Check / Clear DTC CHECK / CLEAR NOTICE: When the diagnosis system is changed from normal mode to check mode or vice versa, all DTCs and freeze frame data recorded in normal mode are cleared. Before changing modes, always check and make a note of DTCs and freeze frame data. HINT: DTCs which are s ...