Speedometer Malfunction

METER / GAUGE SYSTEM: Speedometer Malfunction

Speedometer Malfunction

DESCRIPTION

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

NOTE: If the vehicle speed is outside the allowable range when tested, perform the following procedure (On-Vehicle inspection).

PROCEDURE

1. PERFORM ACTIVE TEST BY TECHSTREAM (SPEED METER OPERATION)
(a) Connect Techstream to the DLC3.
(b) Turn the ignition switch to the ON position.
(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: for Canada
OK:
Needle indication is normal.
NG -- REPLACE COMBINATION METER ASSEMBLY
OK -- Continue to next step.
2. READ VALUE OF TECHSTREAM (VEHICLE SPEED METER)
(a) Connect Techstream to the DLC3.
(b) Turn the ignition switch to the ON position.
(c) Turn the tester on.
(d) Enter the following menus: Body Electrical / Combination Meter / Data List.
(e) Check the values by referring to the table below.

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 OF TECHSTREAM (FR/FL/RR/RL WHEEL SPEED)
OK -- REPLACE COMBINATION METER ASSEMBLY
3. READ VALUE OF TECHSTREAM (FR/FL/RR/RL WHEEL SPEED)
(a) Connect Techstream to the DLC3.
(b) Turn the ignition switch to the ON position.
(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:





OK:
Vehicle speed displayed on the tester is almost the same as the actual vehicle speed (calibrated chassis dynamometer).
NG -- GO TO BRAKE CONTROL SYSTEM
OK -- Continue to next step.
4. INSPECT COMBINATION METER ASSEMBLY
(a) Check the input signal waveform.





(1) Remove the combination meter assembly with connector still connected.
(2) Connect the oscilloscope to terminal C7-35 (SI) and body ground.





(3) 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.

Result:





C -- CHECK HARNESS AND CONNECTOR (BRAKE ACTUATOR ASSEMBLY - COMBINATION METER)
B -- CHECK HARNESS AND CONNECTOR (ABS AND TRACTION ACTUATOR ASSEMBLY - COMBINATION METER)
A -- REPLACE COMBINATION METER ASSEMBLY
5. CHECK HARNESS AND CONNECTOR (ABS AND TRACTION ACTUATOR ASSEMBLY - COMBINATION METER)





(a) Disconnect the C7 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 -- Continue to next step.
6. 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 -- REPLACE COMBINATION METER ASSEMBLY
OK -- REPLACE ABS AND TRACTION ACTUATOR ASSEMBLY
7. CHECK HARNESS AND CONNECTOR (BRAKE ACTUATOR ASSEMBLY - COMBINATION METER)





(a) Disconnect the C7 and S2 connectors.
(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. INSPECT COMBINATION METER ASSEMBLY





(a) Disconnect the S2 connector.
(b) Measure the voltage according to the value(s) in the table below.
Standard voltage:





NG -- REPLACE COMBINATION METER ASSEMBLY
OK -- REPLACE BRAKE ACTUATOR ASSEMBLY