Speedometer Malfunction

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.
HINT: Factors that affect the indicated vehicle speed include tire size, tire inflation, and tire wear. The speed indicated on the speedometer has an allowable margin of error. This can be tested using a speedometer tester (calibrated chassis dynamometer). For details about testing and the margin of error, see the reference chart Meter / Gauge System.

WIRING DIAGRAM





INSPECTION PROCEDURE
NOTE: If the vehicle speed is outside the allowable range when tested, perform the following procedure Meter / Gauge System.
HINT:
- Start the inspection from step 1 when using the intelligent tester and start from step 4 when not using the intelligent tester.

PROCEDURE

1. PERFORM ACTIVE TEST USING INTELLIGENT TESTER
(a) Connect the intelligent tester to the DLC3.
(b) Turn the ignition switch to the ON position.
(c) Turn the tester ON.
(d) Enter the following menus: DIAGNOSIS / OBD/MOBD / METER / ACTIVE TEST.
(e) Check the operation by referring to the table below.

METER:





HINT: *1: for U.S.A.
*2: for Canada

OK:
Needle indication is within the allowable range.
NG -- REPLACE COMBINATION METER ASSEMBLY
OK -- Continue to next step.
2. READ VALUE USING INTELLIGENT TESTER
(a) Connect the intelligent tester to the DLC3.
(b) Turn the ignition switch to the ON position.
(c) Turn the tester ON.
(d) Enter the following menus: DIAGNOSIS / OBD/MOBD / METER / DATA LIST.
(e) Check the values by referring to the table below.

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 INTELLIGENT TESTER
OK -- REPLACE COMBINATION METER ASSEMBLY
3. READ VALUE USING INTELLIGENT TESTER
(a) Connect the intelligent tester to the DLC3.
(b) Turn the ignition switch to the ON position.
(c) Turn the tester ON.
(d) Enter the following menus: DIAGNOSIS / OBD/MOBD / ABS/TRAC/VSC / DATA LIST.
(e) Check the values by referring to the table below.

ABS/TRAC/VSC:





OK:
Vehicle speed displayed on the tester is almost the same as the actual vehicle speed.
NG -- GO TO BRAKE CONTROL SYSTEM
OK -- Continue to next step.
4. INSPECT COMBINATION METER ASSEMBLY





(a) Disconnect the S1 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 COMBINATION METER ASSEMBLY





(a) Check the input signal waveform.
(1) Remove the combination meter assembly with connector(s) still connected.
(2) Connect the oscilloscope to terminal C9-18 (SPEED SIGNAL) and body ground.
(3) Start the engine.
(4) Check the signal waveform according to the condition(s) in the table below.






OK:
The waveform is displayed as shown in the illustration.
HINT: As the vehicle speed increases, the cycle of the signal waveform narrows.

NG -- REPLACE SKID CONTROL ECU
OK -- REPLACE COMBINATION METER ASSEMBLY
6. CHECK HARNESS AND CONNECTOR (COMBINATION METER - SKID CONTROL ECU)





(a) Disconnect the C9 and S1 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