Lexus NX manuals

Lexus NX: Speedometer Malfunction

Lexus NX Service Manual / Vehicle Interior / Meter / Gauge / Display / Meter / Gauge System / Speedometer Malfunction

DESCRIPTION

The combination meter assembly receives vehicle speed signals from the brake booster with master cylinder assembly (skid control ECU) via the CAN communication line. The wheel speed sensors output voltages that vary according to the vehicle speed. The brake booster with master cylinder assembly (skid control ECU) supplies power to the wheel speed sensors. The brake booster with master cylinder assembly (skid control ECU) calculates the vehicle speed based on the pulses of the voltage.

WIRING DIAGRAM

CAUTION / NOTICE / HINT

NOTICE:

  • When replacing the combination meter assembly, make sure to replace it with a new one.
  • If the vehicle speed is outside the allowable range when tested, perform the operation check.

    Click here

HINT:

Before starting the following inspection, check tire size and tire air pressure.

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 (ELECTRONICALLY CONTROLLED BRAKE SYSTEM)

(a) Check for DTCs.

Click here

Chassis > ABS/VSC/TRAC > Trouble Codes

OK:

No DTCs are output.

NG

GO TO ELECTRONICALLY CONTROLLED BRAKE SYSTEM

OK

3.

PERFORM ACTIVE TEST USING TECHSTREAM (SPEED METER 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

Speed Meter Operation

Speedometer
  • OFF, 0, 40, 80, 120, 160, 200, 240 (km/h) (for km/h)
  • OFF, 0, 40, 80, 120 (mph) (for mph)

There is a deviation in the values displayed on the speedometer display (Control range → Speedometer)

with km/h units:
  • 40 → 38.2 to 42.7
  • 80 → 78.3 to 83.3
  • 120 → 118.7 to 123.7
  • 160 → 159.1 to 164.1
  • 200 → 199.5 to 204.5
  • 240 → 239.9 to 244.9
with mph units:
  • 40 → 39.0 to 41.8
  • 80 → 79.2 to 82.4
  • 120 → 119.6 to 122.8
Body Electrical > Combination Meter > Active Test

Tester Display

Speed Meter Operation

OK:

Speedometer indication is normal.

NG

REPLACE COMBINATION METER ASSEMBLY

OK

4.

READ VALUE USING TECHSTREAM (VEHICLE SPEED METER)

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

Click here

Body Electrical > Combination Meter > Data List

Tester Display

Measurement Item

Range

Normal Condition

Diagnostic Note

Vehicle Speed Meter

Vehicle speed

Min.: 0 km/h (0 mph), Max.: 255 km/h (158 mph)

Almost the same as actual vehicle speed

-
Body Electrical > Combination Meter > Data List

Tester Display

Vehicle Speed Meter

HINT:

  • When the Data List values of the ECUs match, an internal malfunction of the combination meter assembly is suspected.
  • When the Data List values of the ECUs do not match, a signal output error of the brake booster with master cylinder assembly (skid control ECU) or an internal malfunction of the combination meter assembly is suspected.

OK:

Vehicle speed displayed on the Techstream is almost the same as the actual vehicle speed measured using a speedometer tester (calibrated chassis dynamometer).

OK

REPLACE COMBINATION METER ASSEMBLY

NG

5.

READ VALUE USING TECHSTREAM (VEHICLE SPEED)

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

Click here

Chassis > ABS/VSC/TRAC > Data List

Tester Display

Measurement Item

Normal Condition

Reference Value

Diagnostic Note

Vehicle Speed

Vehicle speed

Min.: 0 km/h (0 mph), Max.: 326 km/h (202 mph)

Almost the same as actual vehicle speed

-
Chassis > ABS/VSC/TRAC > Data List

Tester Display

Vehicle Speed

OK:

Vehicle speed displayed on the Techstream is almost the same as the actual vehicle speed measured using a speedometer tester (calibrated chassis dynamometer).

NG

REPLACE BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY (SKID CONTROL ECU)

OK

6.

CHECK COMBINATION METER ASSEMBLY

(a) Replace the combination meter assembly.

Click here

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

OK:

The operation of the speedometer returns to normal.

OK

END (COMBINATION METER ASSEMBLY IS DEFECTIVE)
NG

REPLACE BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY (SKID CONTROL ECU)

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