Speed Signal Circuit

METER: METER / GAUGE SYSTEM: Speed Signal Circuit
- Speed Signal Circuit

DESCRIPTION

The combination meter assembly 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 from the skid control ECU. To create this signal, 12 V is output from IG2 which is behind a resistor in the combination meter. 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 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 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 controls its respective system based on the pulse signal. *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 operation. Combination meter components such as the speedometer operate using data received via CAN communication.

WIRING DIAGRAM





INSPECTION PROCEDURE

PROCEDURE

1. CHECK HARNESS AND CONNECTOR (JUNCTION CONNECTOR)

(a) Check for a short in the circuit connected to the junction connector shown in the wiring diagram.

HINT
If voltage is not present, the circuit (ECU) was possibly malfunctioning. This is the circuit that will be diagnosed by following the step A that follows.

(1) Disconnect the junction connectors.





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

Standard voltage:





*1: w/ Smart Key System

*2: w/ Back Door Speaker

Result





B -- INSPECT ECU TERMINAL VOLTAGE (INPUT VOLTAGE)
A -- Continue to next step.

2. SYSTEM CHECK

(a) Check the circuit that did not present voltage in step 6.

Result





*1: w/ Smart Key System

*2: w/ Navigation System

*3: w/o Navigation System

*4: w/ Back Door Speaker

E -- CHECK HARNESS AND CONNECTOR (STEREO COMPONENT AMPLIFIER CIRCUIT)

D -- CHECK HARNESS AND CONNECTOR (RADIO RECEIVER ASSEMBLY CIRCUIT)

C -- CHECK HARNESS AND CONNECTOR (NAVIGATION RECEIVER CIRCUIT)

B -- CHECK HARNESS AND CONNECTOR (HYBRID VEHICLE CONTROL ECU CIRCUIT)
A -- Continue to next step.

3. CHECK HARNESS AND CONNECTOR (MAIN BODY ECU CIRCUIT)

(a) Disconnect the D9 main body ECU connector.





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

Standard resistance:





NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR

OK -- REPLACE MAIN BODY ECU

4. CHECK HARNESS AND CONNECTOR (HYBRID VEHICLE CONTROL ECU CIRCUIT)

(a) Disconnect the D72 hybrid vehicle control ECU connector.





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

Standard resistance:





NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR

OK -- REPLACE HYBRID VEHICLE CONTROL ECU Removal

5. CHECK HARNESS AND CONNECTOR (NAVIGATION RECEIVER CIRCUIT)

(a) Disconnect the E5 navigation receiver assembly connector.





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

Standard resistance:





NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR

OK -- REPLACE NAVIGATION RECEIVER ASSEMBLY Removal

6. CHECK HARNESS AND CONNECTOR (RADIO RECEIVER ASSEMBLY CIRCUIT)

(a) Disconnect the E3 radio receiver assembly connector.





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

Standard resistance:





NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR

OK -- REPLACE RADIO RECEIVER ASSEMBLY Removal

7. CHECK HARNESS AND CONNECTOR (STEREO COMPONENT AMPLIFIER CIRCUIT)

(a) Disconnect the N14 stereo component amplifier connector.





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

Standard resistance:





NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR

OK -- REPLACE STEREO COMPONENT AMPLIFIER Removal

8. INSPECT ECU TERMINAL VOLTAGE (INPUT VOLTAGE)

(a) Disconnect the E1 meter connector.





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

Standard voltage:





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

NG -- CHECK HARNESS AND CONNECTOR (COMBINATION METER - JUNCTION CONNECTOR)
OK -- Continue to next step.

9. INSPECT COMBINATION METER (OUTPUT VOLTAGE)

(a) Reconnect the E1 meter connector.

(b) Disconnect the A44 skid control ECU connector.





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

Standard voltage:





NG -- CHECK HARNESS AND CONNECTOR (COMBINATION METER - SKID CONTROL ECU)
OK -- Continue to next step.

10. INSPECT SKID CONTROL ECU (INPUT WAVEFORM)

(a) Check the input waveform.





(1) Reconnect the A44 skid control ECU connector.

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

(3) Connect an oscilloscope to terminals E1-29 (SI) and body ground.

(4) Turn the ignition switch to ON (READY).

(5) Turn the wheel slowly.

(6) Check the signal waveform according to the condition(s) in the table below.





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.

NG -- REPLACE SKID CONTROL ECU Removal

OK -- REPLACE COMBINATION METER ASSEMBLY Removal

11. CHECK HARNESS AND CONNECTOR (COMBINATION METER - JUNCTION CONNECTOR)

(a) Disconnect the junction connector.





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

Standard resistance:





NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR

OK -- REPLACE JUNCTION CONNECTOR

12. CHECK HARNESS AND CONNECTOR (COMBINATION METER - SKID CONTROL ECU)

(a) Disconnect the E1 meter connector.





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

Standard resistance:





NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR

OK -- REPLACE COMBINATION METER ASSEMBLY Removal