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. INSPECT ECU TERMINAL VOLTAGE (INPUT VOLTAGE)
(a) Disconnect the E1 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.
2. INSPECT COMBINATION METER (OUTPUT VOLTAGE)
(a) Reconnect the E1 combination 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.
3. INSPECT SKID CONTROL ECU (INPUT WAVEFORM)
(a) Check the input waveform.
(1) Reconnect the A44 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) Power switch 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
OK -- REPLACE COMBINATION METER
4. 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 -- Continue to next step.
5. 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/ Navigation System
*3: for Separate Type Amplifier System
Result:
B -- REPLACE JUNCTION CONNECTOR
A -- Continue to next step.
6. SYSTEM CHECK
(a) Check the circuit that did not present voltage in step 6.
Result:
*1: w/ Navigation System
*2: for Separate Type Amplifier System
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.
7. CHECK HARNESS AND CONNECTOR (MAIN BODY ECU CIRCUIT)
(a) Disconnect the D9 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
8. CHECK HARNESS AND CONNECTOR (HYBRID VEHICLE CONTROL ECU CIRCUIT)
(a) Disconnect the D35 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 (for 3MZ-FE)
9. CHECK HARNESS AND CONNECTOR (NAVIGATION RECEIVER CIRCUIT)
(a) Disconnect the E5 (*) connector.
(b) Measure the resistance according to the value(s) in the table below.
Standard resistance:
*: w/ Navigation System
NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- REPLACE NAVIGATION RECEIVER
10. CHECK HARNESS AND CONNECTOR (RADIO RECEIVER ASSEMBLY CIRCUIT)
(a) Disconnect the E3 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
11. CHECK HARNESS AND CONNECTOR (STEREO COMPONENT AMPLIFIER CIRCUIT)
(a) Disconnect the N14 connector.
(b) Measure the resistance according to the value(s) in the table below.
Standard resistance:
*: for Separate Type Amplifier System
NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- REPLACE STEREO COMPONENT AMPLIFIER
12. CHECK HARNESS AND CONNECTOR (COMBINATION METER - SKID CONTROL ECU)
(a) Disconnect the E1 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