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:





*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. CHECK BRAKE CONTROL SYSTEM

(a) Check if brake control system DTC is output.

Result:





B -- GO TO BRAKE CONTROL SYSTEM
A -- Continue to next step.

3. READ VALUE USING TECHSTREAM (VEHICLE SPEED METER, FL/FR/RL/RR WHEEL SPEED)

(a) Connect the Techstream to the DLC3.

(b) Turn the engine switch on (IG).

(c) Turn the Techstream on.

(d) Enter the following menus:

(1) for Combination Meter: Body Electrical / Combination Meter / Data List.

(2) for ABS/VSC/TRAC: Chassis / ABS/VSC/TRAC / Data List.

(e) Check the values by referring to the values in the table below.

Combination Meter





ABS/VSC/TRAC





OK:

When the Data List values of the ECUs match, an internal malfunction of the combination meter assembly is suspected.

NG:

When the Data List values of the ECUs do not match, a signal output error of the skid control ECU or an internal malfunction of the combination meter assembly is suspected.

NG -- INSPECT COMBINATION METER ASSEMBLY (OUTPUT VOLTAGE)

OK -- REPLACE COMBINATION METER ASSEMBLY

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