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METER / GAUGE SYSTEM > Speed Signal Circuit

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DESCRIPTION

The combination meter assembly (No. 3 meter circuit plate) receives the vehicle speed signal from this circuit. The wheel speed sensors produce an output that varies according to the vehicle speed. The wheel speed sensor output is received by the skid control ECU which uses this information to create the vehicle speed sensor signal*1. The vehicle speed sensor signal consists of pulses sent to the combination meter assembly from the skid control ECU. To create this signal, 12 V is output from IG2 which is behind a resistor in the combination meter assembly. This voltage is sent to the skid control ECU. The pulse signal is created by switching the transistor in the skid control ECU on and off, making the voltage on the wire drop to 0 V. A similar system is used for the output of this signal from the combination meter assembly via terminal +S. A voltage of 12 V or 5 V is applied to terminal +S from each ECU or relay that is connected to this terminal. The transistor in the combination meter assembly is controlled by the signal from the skid control ECU. When this transistor is turned on, this transistor makes the voltage supplied by the various ECUs (via their respective internal resistors) drop to 0 V. Each ECU connected to terminal +S of the combination meter assembly (No. 3 meter circuit plate) controls its respective system based on the pulse signal.
  1. *1: This vehicle speed sensor signal is created by the skid control ECU. There is no actual component that is referred to as the vehicle speed sensor. In addition, for some other systems, vehicle speed information may be exchanged using CAN communication.

HINT:
This circuit is used for the systems connected to terminal +S. This signal is not used for combination meter assembly operation. Combination meter assembly components such as the speedometer operate using data received via CAN communication.


WIRING DIAGRAM


E292833E01


INSPECTION PROCEDURE

1.INSPECT ECU TERMINAL VOLTAGE (INPUT VOLTAGE)


    E160303E51

  1. Disconnect the L27 connector.

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

    Standard Voltage:
    Tester Connection
    		Condition
    		Specified Condition
    L27-7 (+S) - Body ground
    		Power switch on (IG)
    		4.5 to 14 V

    Text in Illustration 
    *1
    		Front view of wire harness connector
    (to Combination Meter Assembly)

    HINT:
    If any of the ECUs specified in the wiring diagram supplies power to the combination meter assembly, the combination meter assembly will output a waveform.



NG
Go to step 5
OK


2.INSPECT COMBINATION METER ASSEMBLY (NO. 3 METER CIRCUIT PLATE) (OUTPUT VOLTAGE)

  1. Reconnect the L27 connector.



    C209401E14

  1. Disconnect the A58 connector.

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

    Standard Voltage:
    Tester Connection
    		Condition
    		Specified Condition
    A58-11 (SP1) - Body ground
    		Power switch on (IG)
    		11 to 14 V

    Text in Illustration 
    *1
    		Front view of wire harness connector
    (to Skid Control ECU)



NG
Go to step 4
OK


3.INSPECT SKID CONTROL ECU (INPUT WAVEFORM)


    E159354E24

  1. Check the input waveform.

    1. Reconnect the A58 connector.

    2. Remove the combination meter assembly with the connector(s) still connected.

    3. Connect an oscilloscope to terminal L27-8 (SI) and body ground.

    4. Turn the power switch on (IG).

    5. Turn the wheel slowly.

    6. Check the signal waveform according to the condition(s) in the table below.
      Item
      		Condition
      Tool setting
      		5 V/DIV., 20 ms./DIV.
      Vehicle condition
      		Power switch on (IG), wheel being rotated
      Text in Illustration 
      *1
      		Component with harness connected
      (Combination Meter Assembly)

      OK:
      The waveform is displayed as shown in the illustration.

      HINT:
      When the system is functioning normally, one wheel revolution generates 4 pulses. As the vehicle speed increases, the width indicated by (A) in the illustration narrows.

      Result:
      Result
      		Proceed to
      OK
      		A
      NG (for LHD)
      		B
      NG (for RHD)
      		C



B
REPLACE SKID CONTROL ECU (Click here)

C
REPLACE SKID CONTROL ECU (Click here)
A

REPLACE COMBINATION METER ASSEMBLY (NO. 3 METER CIRCUIT PLATE) (Click here)  

4.CHECK HARNESS AND CONNECTOR (NO. 3 METER CIRCUIT PLATE - SKID CONTROL ECU)

  1. Disconnect the L27 and A58 connectors.

  1. Measure the resistance according to the value(s) in the table below.

    Standard Resistance:
    Tester Connection
    		Condition
    		Specified Condition
    A58-11 (SP1) - L27-8 (SI)
    		Always
    		Below 1 Ω
    A58-11 (SP1) - Body ground
    		Always
    		10 kΩ or higher



NG
REPAIR OR REPLACE HARNESS OR CONNECTOR
OK

REPLACE COMBINATION METER ASSEMBLY (NO. 3 METER CIRCUIT PLATE) (Click here)  

5.CHECK HARNESS AND CONNECTOR (NO. 3 METER CIRCUIT PLATE - RADIO AND DISPLAY RECEIVER ASSEMBLY, NAVIGATION ECU SUB-ASSEMBLY)

  1. Disconnect the L27, 3A and L149*1, L130*2 or L126*3 connectors.

  1. Measure the resistance according to the value(s) in the table below.

    Standard Resistance:
    Tester Connection
    		Condition
    		Specified Condition
    L149-17 (SPD)*1 - L27-7 (+S)
    		Always
    		Below 1 Ω
    L130-17 (SPD)*2 - L27-7 (+S)
    		Always
    		Below 1 Ω
    L126-3 (SPD)*3 - L27-7 (+S)
    		Always
    		Below 1 Ω
    L27-7 (+S) - Body ground
    		Always
    		10 kΩ or higher

    1. *1: for Radio and Display Type
    2. *2: for Navigation Receiver Type
    3. *3: except Navigation Receiver Type and Radio and Display Type



NG
REPAIR OR REPLACE HARNESS OR CONNECTOR
OK


6.INSPECT RADIO AND DISPLAY RECEIVER ASSEMBLY, NAVIGATION ECU SUB-ASSEMBLY (OUTPUT VOLTAGE)

  1. Reconnect the L149*1, L130*2 or L126*3 connector.

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

    Standard Voltage:
    Tester Connection
    		Condition
    		Specified Condition
    L149-17 (SPD)*1 - Body ground
    		Power switch on (IG)
    		4 to 14 V
    L130-17 (SPD)*2 - Body ground
    		Power switch on (IG)
    		4 to 14 V

    1. *1: for Radio and Display Type
    2. *2: for Navigation Receiver Type

    Result:
    Result
    		Proceed to
    OK
    		A
    NG (for Radio and Display Type)
    		B
    NG (for Navigation Receiver Type)
    		C



B
REPLACE RADIO AND DISPLAY RECEIVER ASSEMBLY (Click here)

C
REPLACE NAVIGATION ECU SUB-ASSEMBLY (Click here)
A


7.CHECK HARNESS AND CONNECTOR (COMBINATION METER ASSEMBLY - NO. 3 JUNCTION BLOCK)

  1. Measure the resistance according to the value(s) in the table below.

    Standard Resistance:
    Tester Connection
    		Condition
    		Specified Condition
    L27-7 (+S) - 3A-26*1
    		Always
    		Below 1 Ω
    L27-7 (+S) - 3A-47*2
    		Always
    		Below 1 Ω
    L27-7 (+S) - Body ground
    		Always
    		10 kΩ or higher

    1. *1: for LHD
    2. *2: for RHD



NG
REPAIR OR REPLACE HARNESS OR CONNECTOR
OK


8.CHECK HARNESS AND CONNECTOR (NO. 3 JUNCTION BLOCK (INSTRUMENT PANEL WIRE))


  1. Inspect for a short in the circuit that is connected to the junction block connector shown in the wiring diagram.

    HINT:
    If voltage is not present, it is possible that an ECU or circuit has a malfunction. The malfunctioning ECU or circuit will be diagnosed in the following steps.



    1. Disconnect the 3B connector.


      E188203E13

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

      Standard Voltage:
      Tester Connection
      		Condition
      		Specified Condition
      3A-2*1 - Body ground
      		Power switch on (IG)
      		4.5 to 14 V
      3A-9*2 - Body ground
      		Power switch on (IG)
      		4.5 to 14 V
      3B-1 - Body ground
      		Power switch on (IG)
      		4.5 to 14 V
      3B-85*1 - Body ground
      		Power switch on (IG)
      		4.5 to 14 V
      3B-82*2 - Body ground
      		Power switch on (IG)
      		4.5 to 14 V

      1. *1: for LHD
      2. *2: for RHD

      Text in Illustration 
      *1
      		Front view of wire harness connector
      (to No. 3 Junction Block)
      		-
      		-

      Result:
      Result
      		Proceed to
      Voltage is not present in one circuit.
      		A
      Voltage is present in all the circuits.
      		B



B
REPLACE NO. 3 JUNCTION BLOCK (INSTRUMENT PANEL WIRE)
A


9.CHECK HARNESS AND CONNECTOR (NO. 3 JUNCTION BLOCK - NO. 4 JUNCTION BLOCK)

  1. Disconnect the 4A connector.

  1. Measure the resistance according to the value(s) in the table below.

    Standard Resistance:
    Tester Connection
    		Condition
    		Specified Condition
    3B-85*1 - 4A-21
    		Always
    		Below 1 Ω
    3B-82*2 - 4A-21
    		Always
    		Below 1 Ω
    3B-85 - Body ground
    		Always
    		10 kΩ or higher

    1. *1: for LHD
    2. *2: for RHD



NG
REPAIR OR REPLACE HARNESS OR CONNECTOR
OK


10.CHECK HARNESS AND CONNECTOR (NO. 4 JUNCTION BLOCK (INSTRUMENT PANEL WIRE))


  1. Inspect for a short in the circuit that is connected to the junction block connector shown in the wiring diagram.

    HINT:
    If voltage is not present, it is possible that an ECU or circuit has a malfunction. The malfunctioning ECU or circuit will be diagnosed in the following steps.

    1. Disconnect the 4B connector.



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


      E188203E14

      Standard Voltage:
      Tester Connection
      		Condition
      		Specified Condition
      4A-34 - Body ground
      		Power switch on (IG)
      		4.5 to 14 V
      4A-56 - Body ground
      		Power switch on (IG)
      		4.5 to 14 V
      4A-69 - Body ground
      		Power switch on (IG)
      		4.5 to 14 V
      4B-45 - Body ground
      		Power switch on (IG)
      		4.5 to 14 V


      Text in Illustration 
      *1
      		Front view of wire harness connector
      (to No. 4 Junction Block)
      		-
      		-

      Result:
      Result
      		Proceed to
      Voltage is not present in one circuit.
      		A
      Voltage is present in all the circuits.
      		B



B
REPLACE NO. 4 JUNCTION BLOCK (INSTRUMENT PANEL WIRE)
A


11.SYSTEM CHECK

  1. Select the circuit for which voltage was not present in step 8 or 10.

    Result:

    Tester Connection
    		System that Uses the Circuit
    		Proceed to
    3A-2*1 - Body ground
    		Entry and Start System
    		A
    3A-9*2 - Body ground
    4B-45*3 - Body ground
    		Wiper and Washer System
    		B
    4A-69*4 - Body ground
    		Navigation System
    		C
    4A-56*5 - Body ground
    		Lighting System
    		D
    3B-1*1, *6 - Body ground
    		Tire Pressure Warning System
    		E
    4A-34*2, *6 - Body ground

    1. *1: for LHD
    2. *2: for RHD
    3. *3: w/ Auto Wiper System
    4. *4: for 8 Speakers
    5. *5: w/ Automatic Headlight Beam Level Control
    6. *6: w/ Tire Pressure Warning System



B
Go to step 13

C
Go to step 14

D
Go to step 15

E
Go to step 16
A


12.CHECK HARNESS AND CONNECTOR (POWER MANAGEMENT CONTROL ECU CIRCUIT)

  1. Disconnect the L5 connector.

  1. Measure the resistance according to the value(s) in the table below.

    Standard Resistance:
    Tester Connection
    		Condition
    		Specified Condition
    L5-14 (SPDI) - Body ground
    		Always
    		10 kΩ or higher



NG
REPAIR OR REPLACE HARNESS OR CONNECTOR
OK

REPLACE POWER MANAGEMENT CONTROL ECU (Click here)  

13.CHECK HARNESS AND CONNECTOR (WINDSHIELD WIPER RELAY ASSEMBLY CIRCUIT)

  1. Disconnect the L114 connector.

  1. Measure the resistance according to the value(s) in the table below.

    Standard Resistance:
    Tester Connection
    		Condition
    		Specified Condition
    L114-19 (SPD) - Body ground
    		Always
    		10 kΩ or higher



NG
REPAIR OR REPLACE HARNESS OR CONNECTOR
OK

REPLACE WINDSHIELD WIPER RELAY ASSEMBLY (Click here)  

14.CHECK HARNESS AND CONNECTOR (STEREO COMPONENT AMPLIFIER ASSEMBLY CIRCUIT)

  1. Disconnect the L143 connector.

  1. Measure the resistance according to the value(s) in the table below.

    Standard Resistance:
    Tester Connection
    		Condition
    		Specified Condition
    L143-11 (SPD) - Body ground
    		Always
    		10 kΩ or higher



NG
REPAIR OR REPLACE HARNESS OR CONNECTOR
OK

REPLACE STEREO COMPONENT AMPLIFIER ASSEMBLY (Click here)  

15.CHECK HARNESS AND CONNECTOR (HEADLIGHT LEVELING ECU CIRCUIT)

  1. Disconnect the A48 connector.

  1. Measure the resistance according to the value(s) in the table below.

    Standard Resistance:
    Tester Connection
    		Condition
    		Specified Condition
    A48-16 (SPDR) - Body ground
    		Always
    		10 kΩ or higher



NG
REPAIR OR REPLACE HARNESS OR CONNECTOR
OK

REPLACE HEADLIGHT LEVELING ECU ASSEMBLY (Click here)  

16.CHECK HARNESS AND CONNECTOR (TIRE PRESSURE WARNING ECU AND RECEIVER CIRCUIT)

  1. Disconnect the R33 connector.

  1. Measure the resistance according to the value(s) in the table below.

    Standard Resistance:
    Tester Connection
    		Condition
    		Specified Condition
    R33-2 (SPD) - Body ground
    		Always
    		10 kΩ or higher



NG
REPAIR OR REPLACE HARNESS OR CONNECTOR
OK

REPLACE TIRE PRESSURE WARNING ECU AND RECEIVER (Click here)