Tachometer Malfunction

METER / GAUGE / DISPLAY: METER / GAUGE SYSTEM: Tachometer Malfunction
- Tachometer Malfunction

DESCRIPTION

The meter CPU receives engine speed signals from the ECM in this circuit. The ECM transmits engine speed signals as pulses to the meter CPU. The meter CPU calculates the engine speed converting 4 pulses to 2 revolutions.

WIRING DIAGRAM





INSPECTION PROCEDURE

PROCEDURE

1. PERFORM ACTIVE TEST USING TECHSTREAM (TACHO 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 values in the table below.

Combination Meter





NG -- REPLACE COMBINATION METER ASSEMBLY Removal
OK -- Continue to next step.

2. READ VALUE USING TECHSTREAM (ENGINE RPM)

(a) Connect the Techstream to the DLC3.

(b) Engine start.

(c) Turn the Techstream 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





Result:





B -- READ VALUE USING TECHSTREAM (ENGINE SPEED)

C -- CHECK HARNESS AND CONNECTOR (COMBINATION METER ASSEMBLY - ECM)

A -- REPLACE COMBINATION METER ASSEMBLY Removal

3. READ VALUE USING TECHSTREAM (ENGINE SPEED)

(a) Connect the Techstream to the DLC3.

(b) Engine start.

(c) Turn the Techstream on.

(d) Enter the following menus: Powertrain / Engine and ECT / Data List.

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

Engine and ECT





Result:





B -- GO TO SFI SYSTEM (for 4GR-FSE) SFI System

C -- GO TO SFI SYSTEM (for 2GR-FSE) SFI System
A -- Continue to next step.

4. CHECK HARNESS AND CONNECTOR (COMBINATION METER ASSEMBLY - ECM)

(a) Disconnect the A6 and J34 connectors.





(b) Measure the resistance according to the value(s) in the table below.

Standard Resistance:





Text in Illustration





NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- Continue to next step.

5. INSPECT ECM (INPUT WAVEFORM)

(a) Check the input signal waveform.





(1) Reconnect the A6 connector.

(2) Connect the oscilloscope to the terminal J34-16 (S) 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
When the system is functioning normally, one engine revolution generates 4 pulses. As the engine speed increases, the width indicated by (A) in the illustration narrows.

Result:





Text in Illustration





B -- REPLACE ECM (for 4GR-FSE) Removal

C -- REPLACE ECM (for 2GR-FSE) Removal

A -- REPLACE COMBINATION METER ASSEMBLY Removal