Speedometer Malfunction
METER: METER / GAUGE SYSTEM: Speedometer Malfunction
- Speedometer Malfunction
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.
* The meter CPU calculates the vehicle speed converting 4 pulses to 1 revolution
WIRING DIAGRAM
INSPECTION PROCEDURE
HINT
Before starting circuit inspection, check tire size and tire pressure.
PROCEDURE
1. PERFORM ACTIVE TEST USING TECHSTREAM (SPEED METER OPERATION)
(a) Connect Techstream to the DLC3.
(b) Turn the engine switch on (IG).
(c) Turn the tester ON.
(d) Enter the following menus: Body Electrical / Combination Meter / Active Test.
(e) Check the operation by referring to the table below.
Combination Meter:
Combination Meter::
(f) *1: for U.S.A.
*2: except U.S.A.
OK:
Needle indication is normal.
NG -- REPLACE COMBINATION METER ASSEMBLY
OK -- Continue to next step.
2. READ VALUE USING TECHSTREAM (VEHICLE SPEED METER)
(a) Connect Techstream to the DLC3.
(b) Turn the engine switch on (IG).
(c) Turn the tester ON.
(d) Enter the following menus: Body Electrical / Combination Meter / Data List.
(e) Check the values by referring to the values in the table below.
Combination Meter:
Combination Meter::
OK:
Vehicle speed displayed on the tester is almost the same as the actual vehicle speed measured using a speedometer tester (calibrated chassis dynamometer).
NG -- READ VALUE USING TECHSTREAM (FL/FR/RL/RR WHEEL SPEED)
OK -- REPLACE COMBINATION METER ASSEMBLY
3. READ VALUE USING TECHSTREAM (FL/FR/RL/RR WHEEL SPEED)
(a) Connect the Techstream to the DLC3.
(b) Turn the engine switch on (IG).
(c) Turn the tester ON.
(d) Enter the following menus: Chassis / ABS/VSC/TRAC / Data List.
(e) Check the values by referring to the table below.
ABS/VSC/TRAC:
ABS/VSC/TRAC::
OK:
Vehicle speed displayed on the tester is almost the same as the actual vehicle speed measured using a speedometer tester (calibrated chassis dynamometer).
NG -- GO TO BRAKE CONTROL SYSTEM
OK -- Continue to next step.
4. INSPECT COMBINATION METER ASSEMBLY (OUTPUT VOLTAGE)
(a) Disconnect the A58 connector.
(b) 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.
5. INSPECT SKID CONTROL ECU (INPUT WAVEFORM)
(a) Check the input signal waveform.
(1) Reconnect the A58 connector.
(2) Remove the combination meter assembly with connector(s) still connected.
(3) Connect the oscilloscope to the terminals J34-17 (SI) and body ground.
(4) 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
6. CHECK HARNESS AND CONNECTOR (COMBINATION METER - SKID CONTROL ECU)
(a) Disconnect the A58 and J34 connectors.
(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