Speed Signal Circuit

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

DESCRIPTION

The combination meter 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

1. for 2ZR-FE

2. for 2AZ-FE

INSPECTION PROCEDURE

PROCEDURE

1. INSPECT ECU TERMINAL VOLTAGE (INPUT VOLTAGE)

(a) Disconnect the E55 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 supplies power to the combination meter, the combination meter will output a waveform.

NG -- CHECK HARNESS AND CONNECTOR
OK -- Continue to next step.

2. INSPECT COMBINATION METER (OUTPUT VOLTAGE)

(a) Reconnect the E55 connector.

(b) Disconnect the A39*1 or A38*2 connector.

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

Standard Voltage:

* *1: w/o VSC

* *2: w/ VSC

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 A39*1 or A38*2 connector.

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

(3) Connect the oscilloscope to terminal E55-35 (SI) and body ground.

(4) Turn the ignition switch to ON.

(5) Turn a drive wheel slowly.

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

### ptxt ### *1: w/o VSC
### ptxt ### *2: w/ VSC

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:

C -- REPLACE SKID CONTROL ECU (w/ VSC)

B -- REPLACE SKID CONTROL ECU (w/o VSC)

A -- REPLACE COMBINATION METER ASSEMBLY

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

(a) Disconnect the E55 connector.

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

Standard Resistance:

* *1: w/o VSC

* *2: w/ VSC

NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR

OK -- REPLACE COMBINATION METER ASSEMBLY

5. CHECK HARNESS AND CONNECTOR

(a) Inspect for a short in the circuits connected to the combination meter 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 E55 and 2E and E32 (*1) and E52 (*2) and E44 (*3) connectors.

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

Standard Resistance:

### ptxt ### *1: w/ Radio Receiver
### ptxt ### *2: w/ Navigation Receiver Assembly
### ptxt ### *3: w/ Tire Pressure Warning System
NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- Continue to next step.

6. CHECK TIRE PRESSURE WARNING ECU (OUTPUT VOLTAGE)

HINT
For vehicles not equipped with a tire pressure warning system, proceed to the next step.

(a) Reconnect the E44 connector.

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

Standard Resistance:

HINT
If the result is not as specified, there may be a short in the tire pressure warning ECU.

NG -- REPLACE TIRE PRESSURE WARNING ECU
OK -- Continue to next step.

7. CHECK RADIO RECEIVER (OUTPUT VOLTAGE)

HINT
For vehicles not equipped with a radio receiver, proceed to the next step.

(a) Reconnect the E32 connector.

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

Standard Resistance:

HINT
If the result is not as specified, there may be a short in the radio receiver.

NG -- REPLACE RADIO RECEIVER
OK -- Continue to next step.

8. CHECK NAVIGATION RECEIVER ASSEMBLY (OUTPUT VOLTAGE)

(a) Reconnect the E52 connector.

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

Standard Resistance:

HINT
If the result is not as specified, there may be a short in the navigation receiver assembly.

NG -- REPLACE NAVIGATION RECEIVER ASSEMBLY
OK -- Continue to next step.

9. CHECK INSTRUMENT PANEL JUNCTION BLOCK

(a) Inspect for a short in the circuit that is connected to the combination meter 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 2C, 2D, and 2E connectors.

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

Standard Voltage:

*1: w/ Navigation System

*2: w/ Sliding Roof

Result:

C -- CHECK SLIDING ROOF CONTROL ECU (SLIDING ROOF CONTROL ECU CIRCUIT)

B -- CHECK HARNESS AND CONNECTOR (ECM CIRCUIT)

A -- REPLACE INSTRUMENT PANEL JUNCTION BLOCK

10. CHECK HARNESS AND CONNECTOR (ECM CIRCUIT)

(a) Disconnect the A37 connector.

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

Standard Resistance:

Result:

C -- REPAIR OR REPLACE HARNESS OR CONNECTOR

B -- REPLACE ECM (for 2ZR-FE)

A -- REPLACE ECM (for 2AZ-FE)

11. CHECK SLIDING ROOF CONTROL ECU (SLIDING ROOF CONTROL ECU CIRCUIT)

HINT
For vehicles not equipped with a sliding roof, proceed to the next step.

(a) Reconnect the 2C, 2D, and 2E connectors.

(b) Disconnect the O2 connector.

HINT
If the speed signal circuit operates normally after disconnecting the sliding roof control ECU, there may be a short in the sliding roof control ECU.

NG -- CHECK STEREO COMPONENT AMPLIFIER

OK -- REPLACE SLIDING ROOF CONTROL ECU

12. CHECK STEREO COMPONENT AMPLIFIER

HINT
For vehicles not equipped with a stereo component amplifier, proceed to the next step.

(a) Reconnect the 2C, 2D, and 2E connectors.

(b) Disconnect the E34 connector.

HINT
If the speed signal circuit operates normally after disconnecting the stereo component amplifier, there may be a short in the stereo component amplifier.

NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR

OK -- REPLACE STEREO COMPONENT AMPLIFIER