Lexus NX: Tachometer Malfunction

DESCRIPTION

In this circuit, the combination meter assembly receives engine speed signals from the hybrid vehicle control ECU via the CAN communication system. The combination meter assembly displays the engine speed calculated based on the data received from the hybrid vehicle control ECU.

WIRING DIAGRAM

CAUTION / NOTICE / HINT

NOTICE:

When replacing the combination meter assembly, make sure to replace it with a new one.

PROCEDURE

1.

CHECK FOR DTC (CAN COMMUNICATION SYSTEM)

(a) Check for DTCs.

Click here

OK:

No DTCs are output.

NG

GO TO CAN COMMUNICATION SYSTEM

OK

2.

CHECK FOR DTC (HYBRID CONTROL SYSTEM)

(a) Check for DTCs.

Click here

Powertrain > Hybrid Control > Trouble Codes

OK:

No DTCs are output.

NG

GO TO HYBRID CONTROL SYSTEM

OK

3.

PERFORM ACTIVE TEST USING TECHSTREAM (TACHOMETER OPERATION)

(a) Using the Techstream, perform the Active Test.

Click here

Body Electrical > Combination Meter > Active Test

Tester Display

Measurement Item

Control Range

Diagnostic Note

TachoMeter Operation

Tachometer

OFF, 0, 1000, 2000, 3000, 4000, 5000, 6000 or 7000 (rpm)

-

Body Electrical > Combination Meter > Active Test

Tester Display

TachoMeter Operation

OK:

Tachometer indication is normal.

NG

REPLACE COMBINATION METER ASSEMBLY

OK

4.

READ VALUE USING TECHSTREAM (ENGINE REVOLUTION, ENGINE RPM)

(a) Using the Techstream, read the Data List.

Click here

Powertrain > Hybrid Control > Data List

Tester Display

Measurement Item

Normal Condition

Reference Value

Diagnostic Note

Engine Revolution

Engine speed

Min.: 0 rpm, Max.: 16383 rpm

Actual engine speed

-

Body Electrical > Combination Meter > Data List

Tester Display

Measurement Item

Range

Normal Condition

Diagnostic Note

Engine Rpm

Engine speed

Min.: 0 rpm, Max.: 12750 rpm

Actual engine speed

-

Powertrain > Hybrid Control > Data List

Tester Display

Engine Revolution

Body Electrical > Combination Meter > Data List

Tester Display

Engine Rpm

HINT:

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

OK:

The Data List values of the ECUs do not match.

NG

REPLACE HYBRID VEHICLE CONTROL ECU

OK

5.

CHECK COMBINATION METER ASSEMBLY

(a) Replace the combination meter assembly.

Click here

(b) Check that the operation of the tachometer returns to normal.

OK:

The operation of the tachometer returns to normal.

OK

END (COMBINATION METER ASSEMBLY IS DEFECTIVE)

NG

REPLACE HYBRID VEHICLE CONTROL ECU

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