Speed Signal Circuit
METER: METER / GAUGE SYSTEM: Speed Signal Circuit
Speed Signal Circuit
DESCRIPTION
The meter CPU receives vehicle speed signals from this circuit. The vehicle speed sensor detects the voltage that varies according to the vehicle speed. The skid control ECU supplies power to the vehicle speed sensor. The skid control ECU detects vehicle speed signals based on the pulses of the voltage. The skid control ECU transmits vehicle speed signals as pulses to the meter CPU. A voltage of 12 V is output from the combination meter assembly and then input to the skid control ECU. The signal is changed to a pulse signal at the transistor in the combination meter assembly.
A voltage of 12 V or 5 V is output from each ECU or relay and then input to the combination meter assembly.
Each ECU controls the respective system based on the pulse signal.
HINT: This circuit is used for another system, and is not used for combination meter operation.
WIRING DIAGRAM
1. for 2GR-FE
INSPECTION PROCEDURE
PROCEDURE
1. INSPECT COMBINATION METER ASSEMBLY
(a) Check the output waveform.
(1) Remove the combination meter assembly with connector(s) still connected.
(2) Connect the oscilloscope to the terminals E20-12 (+S) and body ground.
(3) Turn the engine switch on (IG).
(4) Turn the wheel slowly.
(5) 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 -- INSPECT ECU TERMINAL VOLTAGE
OK -- RETURN TO THE ORIGINAL INSPECTION FOR OTHER SYSTEM
2. INSPECT ECU TERMINAL VOLTAGE
(a) Disconnect the E20 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 - NO. 3 JUNCTION BLOCK)
OK -- Continue to next step.
3. INSPECT COMBINATION METER ASSEMBLY
(a) Reconnect the E20 connector.
(b) Disconnect the A36 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.
4. INSPECT SKID CONTROL ECU
(a) Check the input waveform.
(1) Reconnect the A36 connector.
(2) Remove the combination meter assembly with connector(s) still connected.
(3) Connect the oscilloscope to the terminals E20-14 (SI) and body ground.
(4) Turn the engine switch on (IG).
(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 ASSEMBLY
5. CHECK HARNESS AND CONNECTOR (COMBINATION METER - NO. 3 JUNCTION BLOCK)
(a) Disconnect the 3P to 3U No. 3 junction block 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.
6. CHECK HARNESS AND CONNECTOR (NO. 3 JUNCTION BLOCK)
(a) Inspect for a short in the circuit that connected the No. 3 junction block shown in the wiring diagram.
HINT: If voltage is not present, the circuit (ECU) was possibly the malfunctioning circuit, This is the circuit that will be diagnosed by following the A step that follows.
(1) Disconnect the 3G to 3M and 3A to 3H No. 3 junction block connectors.
(2) Measure the voltage according to the value(s) in the table below.
Standard voltage:
Result:
B -- REPAIR OR REPLACE HARNESS OR CONNECTOR (NO. 3 JUNCTION BLOCK)
A -- Continue to next step.
7. CHECK HARNESS AND CONNECTOR (NO. 3 JUNCTION BLOCK - NO. 4 JUNCTION BLOCK)
(a) Disconnect the 4H to 4M No. 4 junction block 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.
8. CHECK HARNESS AND CONNECTOR (NO. 4 JUNCTION BLOCK)
(a) Disconnect the 4A to 4G No. 4 junction block connector.
(b) Measure the voltage according to the value(s) in the table below.
Standard voltage:
B -- REPAIR OR REPLACE HARNESS AND CONNECTOR (NO.4 JUNCTION BLOCK)
A -- Continue to next step.
9. SYSTEM CHECK
(a) Select the circuit in which is not present voltage in step 8.
Result:
C -- SYSTEM CHECK
B -- CHECK HARNESS AND CONNECTOR (TIRE PRESSURE WARNING ECU CIRCUIT)
A -- Continue to next step.
10. CHECK HARNESS AND CONNECTOR (MAIN BODY ECU CIRCUIT)
(a) Disconnect the E59 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
11. CHECK HARNESS AND CONNECTOR (TIRE PRESSURE WARNING ECU CIRCUIT)
(a) Disconnect the E81 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 TIRE PRESSURE WARNING ECU
12. SYSTEM CHECK
(a) Select the circuit in which is not present voltage in step 8.
Result:
*1: with Auto Wiper System
*2: with Navigation System
*3: for Separate Type Amplifier System
E -- CHECK HARNESS AND CONNECTOR (STEREO COMPONENT AMPLIFIER CIRCUIT)
D -- CHECK HARNESS AND CONNECTOR (MULTI-DISPLAY CIRCUIT)
C -- CHECK HARNESS AND CONNECTOR (WINDSHIELD WIPER RELAY CIRCUIT)
B -- CHECK HARNESS AND CONNECTOR (TCM CIRCUIT)
A -- Continue to next step.
13. CHECK HARNESS AND CONNECTOR (ECM CIRCUIT)
(a) Disconnect the A10 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 ECM
14. CHECK HARNESS AND CONNECTOR (TCM CIRCUIT)
(a) Disconnect the B40 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 TCM
15. CHECK HARNESS AND CONNECTOR (WINDSHIELD WIPER RELAY CIRCUIT)
(a) Disconnect the E11 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 WINDSHIELD WIPER RELAY
16. CHECK HARNESS AND CONNECTOR (MULTI-DISPLAY CIRCUIT)
(a) Disconnect the E62 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 MULTI-DISPLAY
17. CHECK HARNESS AND CONNECTOR (STEREO COMPONENT AMPLIFIER CIRCUIT)
(a) Disconnect the M30 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
18. CHECK HARNESS AND CONNECTOR (COMBINATION METER - SKID CONTROL ECU)
(a) Disconnect the E20 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