Inspection Procedure

NOTE: When replacing the skid control ECU, perform initialization of linear solenoid valve and calibration (see INITIALIZATION ).

CHECK HARNESS AND CONNECTOR (MOMENTARY INTERRUPTION)

Using the Techstream, check for any. momentary interruption in the wire harness and connector corresponding to a DTC (see CHECK FOR INTERMITTENT PROBLEMS ),

ABS / VSC / TRAC:

SKID CONTROL ECU DIAGNOSTIC CHART

Tester Display	Measurement Item / Range	Normal Condition	Diagnostic Note
SPD SEN RR	RR speed sensor open detection /OPEN or NORMAL	NORMAL: Normal condition	-
SPD SEN RL	RL speed sensor open detection / OPEN or NORMAL	NORMAL: Normal condition	-

OK: There are no momentary interruption.

HINT:

Perform the above inspection before removing the sensor and connector.

NG: Go to step 5

OK: Go to Next Step

READ VALUE OF TECHSTREAM (REAR SPEED SENSOR)

Check the DATA LIST for proper functioning of the rear speed sensor.

ABS / VSC / TRAC:

SKID CONTROL ECU DIAGNOSTIC CHART

Tester Display	Measurement Item / Range	Normal Condition	Diagnostic Note
WHEEL SPD RL	Wheel speed sensor (RL) reading / Min.: 0 km/h (0 mph), Max.: 326 km/h (202 mph)	Actual wheel speed	Similar speed as indicated on speedometer
WHEEL SPD RR	Wheel speed sensor (RR) reading / Min.: 0 km/h (0 mph), Max.: 326 km/h (202 mph)	Actual wheel speed	Similar speed as indicated on speedometer

OK: There is almost no difference in the displayed speed value.

HINT:

There is tolerance of +-10% in the speedometer indication,

NG: Go to step 4

OK: Go to Next Step

INSPECT SPEED SENSOR AND SENSOR ROTOR SERRATIONS
1. Connect the oscilloscope to terminals RR+ and RR-, or RL+ and RL- of the skid control ECU,
2. Drive the vehicle at approximately 30 km/h (19 mph), and check the signal waveform.
  OK: A waveform as shown should be output.
  
  HINT:
  - As the vehicle speed (wheel revolution speed) increases, a cycle of the waveform narrows and the fluctuation in the output voltage becomes greater.
  - When noise is identified in the waveform on the oscilloscope, error signals are generated due to the speed sensor rotor's scratches, looseness or foreign matter deposited on it.
    
    Fig 1: Checking Signal Waveform
    Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
NG: Go to step 7

OK: REPLACE SKID CONTROL ECU

INSPECT REAR SPEED SENSOR

Disconnect the rear speed sensor connector.

Measure the resistance of the sensor.

Standard resistance

STANDARD RESISTANCE REFERENCE CHART

Tester Connection	Specified Condition
1 - 2	1.04 to 1.30 kΩ
1 - Body ground	10 kΩ or higher
2 - Body ground	10 kΩ or higher

Fig 2: Measuring Resistance Of Sensor

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

NOTE: Check the speed sensor signal after the replacement (See TEST MODE PROCEDURE ).

NG: REPLACE REAR SPEED SENSOR

OK: Go to Next Step

CHECK WIRE HARNESS (SKID CONTROL ECU - REAR SPEED SENSOR)

Disconnect the S8 and S9 ECU connectors.
Disconnect the A25 and A26 sensor connectors.

Measure the resistance of the wire harness side connectors.

Standard resistance:

for LH

STANDARD RESISTANCE REFERENCE CHART

Tester Connection	Specified Condition
A25-1 (RL+) - S8-35 (RL+)	Below 1 Ω
A25-2 (RL-) - S8-27 (RL-)	Below 1 Ω
A25-1 (RL+) - Body ground	10 kΩ or higher
A25-2 (RL-) - Body ground	10 kΩ or higher

for RH

STANDARD RESISTANCE REFERENCE CHART

Tester Connection	Specified Condition
A26-1 (RR+) - S9-31 (RR+)	Below 1 Ω
A26-2 (RR-) - S9-23 (RR-)	Below 1 Ω
A26-1 (RR+) - Body ground	10 kΩ or higher
A26-2 (RR-) - Body ground	10 kΩ or higher

Fig 3: Disconnecting S8 And S9 ECU Connectors

NG: REPAIR OR REPLACE HARNESS AND CONNECTOR

OK: Go to Next Step

INSPECT SPEED SENSOR AND SENSOR ROTOR SERRATIONS
1. Connect the oscilloscope to terminals RR+ and RR-, or RL+ and RL- of the skid control ECU.
2. Drive the vehicle at approximately 30 km/h (19 mph), and check the signal waveform.
  OK: A waveform as shown should be output.
  
  HINT:
  - As vehicle speed (wheel revolution speed) increases, a cycle of the waveform narrows and the fluctuation in the output voltage becomes greater.
  - When noise is identified in the waveform on the oscilloscope, error signals are generated due to the speed sensor rotor's scratches, looseness or foreign matter deposited on it.
    
    Fig 4: Normal Signal Waveform
    Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
NG: Go to step 7

OK: REPLACE SKID CONTROL ECU
REPLACE SKID CONTROL ECU
1. Check the sensor installation.
  OK: There is no clearance between the sensor and rear axle carrier.
  
  NOTE: Check the speed sensor signal after the replacement (see TEST MODE PROCEDURE ).
NG: REPLACE REAR SPEED SENSOR

Fig 5: Identifying Clearance Between Sensor And Rear Axle Carrier
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

OK: REPLACE SKID CONTROL ECU