Tachometer Malfunction

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

WIRING DIAGRAM





INSPECTION PROCEDURE

PROCEDURE

1. PERFORM ACTIVE TEST USING TECHSTREAM (TACHOMETER OPERATION)

(a) Connect Techstream to the DLC3.

(b) Ignition 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:





OK:

Needle indication is normal.

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

2. READ VALUE USING TECHSTREAM (ENGINE RPM)

(a) Connect Techstream to the DLC3.

(b) Start the engine.

(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:

Engine speed displayed on the tester is almost the same as the actual engine speed.

NG -- READ VALUE USING TECHSTREAM (ENGINE SPEED)

OK -- REPLACE COMBINATION METER ASSEMBLY

3. READ VALUE USING TECHSTREAM (ENGINE SPEED)

(a) Connect Techstream to the DLC3.

(b) Ignition switch on (IG).

(c) Turn the tester 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:





OK:

Engine speed displayed on the tester is almost the same as the actual engine speed.

NG -- GO TO ENGINE CONTROL SYSTEM
OK -- Continue to next step.

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

(a) Disconnect the E30 and A55 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.

5. INSPECT ECM (INPUT WAVEFORM)

(a) Check the input waveform.





(1) Disconnect the E30 connector.

(2) Reconnect the A55 connector.

(3) Connect the oscilloscope to the terminals E30-31 (S) and body ground.

(4) Start the engine.

(5) Check the input waveform according to the condition(s) in the table below.





OK:

The waveform is displayed as shown in the illustration.

NG -- REPLACE ECM

OK -- REPLACE COMBINATION METER ASSEMBLY