Speedometer Malfunction
METER / GAUGE / DISPLAY: METER / GAUGE SYSTEM: Speedometer Malfunction
- Speedometer Malfunction
DESCRIPTION
The meter CPU receives vehicle speed signals from this circuit. The speed sensor detects the wheel speed and sends the appropriate signals to the skid control ECU. 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 On-Vehicle Inspection.
WIRING DIAGRAM
INSPECTION PROCEDURE
NOTICE:
If the vehicle speed is outside the allowable range when tested, perform the following procedure On-Vehicle Inspection.
HINT
Before starting circuit inspection, check tire size and tire pressure.
PROCEDURE
1. PERFORM ACTIVE TEST USING TECHSTREAM (SPEED METER OPERATION)
(a) Connect the Techstream to the DLC3.
(b) Turn the engine switch on (IG).
(c) Turn the Techstream 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 models with mph units
*2: for models with km/h units
OK:
Speedometer indication is normal.
NG -- REPLACE COMBINATION METER Removal
OK -- Continue to next step.
2. CHECK BRAKE CONTROL SYSTEM
(a) Check if the brake control system output the DTC Reading and Clearing Diagnostic Trouble Codes.
Result:
B -- GO TO BRAKE CONTROL SYSTEM How to Proceed With Troubleshooting
A -- Continue to next step.
3. READ VALUE USING TECHSTREAM (FR/FL/RR/RL WHEEL SPEED, VEHICLE SPEED METER)
(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 ABS/VSC/TRAC: Chassis / ABS/VSC/TRAC / Data List.
(2) for Combination Meter: Body Electrical / Combination Meter / Data List.
(e) Check the values by referring to the table below.
ABS/VSC/TRAC
Combination Meter
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 (OUTPUT VOLTAGE)
OK -- REPLACE COMBINATION METER Removal
4. INSPECT COMBINATION METER (OUTPUT VOLTAGE)
(a) Disconnect the A62 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) Remove the combination meter with connector(s) still connected.
(2) Reconnect the A62 connector.
(3) Connect the oscilloscope to the terminals J34-17 (SI) and body ground.
(4) Turn the engine switch on (IG).
(5) Turn the drive 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 drive wheel revolution generates 4 pulses. As the vehicle speed increases, the width indicated by (A) in the illustration narrows.
NG -- REPLACE SKID CONTROL ECU Removal
OK -- REPLACE COMBINATION METER Removal
6. CHECK HARNESS AND CONNECTOR (COMBINATION METER - SKID CONTROL ECU)
(a) Disconnect the J34 and A62 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 Removal