Lexus RX (RX 350L, RX450h) 2016-2025 Repair Manual: Speedometer Malfunction

Lexus RX (RX 350L, RX450h) 2016-2025 Repair Manual / Vehicle Interior / Meter / Gauge / Display / Meter / Gauge System / Speedometer Malfunction

DESCRIPTION

The combination meter assembly receives vehicle speed signals from the brake actuator assembly (skid control ECU) via CAN communication. The speed sensor detects the wheel speed and sends the appropriate signals to the brake actuator assembly (skid control ECU). The brake actuator assembly (skid control ECU) supplies power to the vehicle speed sensor. The brake actuator assembly (skid control ECU) detects vehicle speed signals based on pulses of the voltage.

HINT:

  • Factors that affect the indicated vehicle speed include the tire size, tire inflation, and tire wear. The speed indicated on the speedometer has an allowable margin of error. This can be tested using the Techstream. For details about testing and the margin of error, see the reference chart.

    Click here

  • If the vehicle speed sensor circuit has a malfunction, the brake actuator assembly (skid control ECU) stores DTCs. Troubleshoot the vehicle stability control system.

    Click here

WIRING DIAGRAM

CAUTION / NOTICE / HINT

NOTICE:

  • When replacing the combination meter assembly, always replace it with a new one. If a combination meter assembly which was installed to another vehicle is used, the information stored in it will not match the information from the vehicle and a DTC may be stored.
  • If the vehicle speed is outside the allowable range when tested, perform the on-vehicle inspection.

    Click here

HINT:

  • Before starting the following inspection, check tire size and tire air pressure.
  • Active Test cannot be performed on the speedometer for TFT meter type.

PROCEDURE

1.

CHECK CAN COMMUNICATION SYSTEM

(a) Check if CAN communication DTCs are output.

Click here

Result

Proceed to

CAN communication DTCs are not output.

A

CAN communication DTCs are output.

B
B

GO TO CAN COMMUNICATION SYSTEM

A

2.

CONFIRM MODEL

(a) Choose the model to be inspected.

Result

Proceed to

for Optitron Meter Type

A

for TFT Meter Type

B
B

GO TO STEP 4

A

3.

PERFORM ACTIVE TEST USING TECHSTREAM (SPEED 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) Perform the Active Test according to the display on the Techstream.

Body Electrical > Combination Meter > Active Test

Tester Display

Measurement Item

Control Range

Diagnostic Note

Speed Meter Operation

Speedometer
  • OFF, 0, 40, 80, 120, 160 mph*1
  • OFF, 0, 40, 80, 120, 160, 200, 240 km/h*2

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

for Optitron Meter Type (mph)*1:
  • 40 → 39.6 to 42.4
  • 80 → 80.5 to 83.7
  • 120 → 121.5 to 124.7
for Optitron Meter Type (km/h)*2:
  • 40 → 38.8 to 43.3
  • 80 → 79.6 to 84.6
  • 120 → 120.6 to 125.6
  • 160 → 161.7 to 166.7
  • 200 → 202.7 to 207.7
  • 240 → 243.7 to 248.7
  • *1: for Speedometer with Imperial Units Main Scale
  • *2: for Speedometer with Metric Units Main Scale
Body Electrical > Combination Meter > Active Test

Tester Display

Speed Meter Operation

OK:

Speedometer indication is normal.

NG

REPLACE COMBINATION METER ASSEMBLY

OK

4.

CHECK FOR DTC

(a) Check if vehicle stability control system DTCs are output.

Click here

Chassis > ABS/VSC/TRC/EPB > Trouble Codes

Result

Proceed to

Vehicle stability control system DTCs are not output.

A

Vehicle stability control system DTCs are output.

B
B

GO TO VEHICLE STABILITY CONTROL SYSTEM

A

5.

READ VALUE USING TECHSTREAM (VEHICLE SPEED, VEHICLE SPEED METER)

(a) Connect the Techstream to the DLC3.

(b) Turn the engine switch on (IG).

(c) Turn the Techstream on.

(d) Enter the following menus:

(1) for ABS/VSC/TRC/EPB: Chassis / ABS/VSC/TRC/EPB / Data List.

(2) for Combination Meter: Body Electrical / Combination Meter / Data List.

(e) Read the Data List according to the display on the Techstream.

Chassis > Brake/EPB > Data List

Tester Display

Measurement Item

Range

Normal Condition

Diagnostic Note

Vehicle Speed

Maximum wheel speed sensor reading

Min.: 0 km/h (0 mph), Max.: 6553.5 km/h (4072 mph)

Vehicle stopped: 0 km/h (0 mph)

When driving at constant speed: No large fluctuations
Chassis > Brake/EPB > Data List

Tester Display

Vehicle Speed
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

Result

Proceed to

The Data List values of the ECUs match.

A

The Data List values of the ECUs do not match.

B

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 malfunction of the brake actuator assembly (skid control ECU) or an internal malfunction of the combination meter assembly is suspected.
A

REPLACE COMBINATION METER ASSEMBLY

B

6.

REPLACE COMBINATION METER ASSEMBLY

(a) Replace the combination meter assembly with a new one.

Click here

OK:

The operation of the speedometer returns to normal.

OK

END
NG

REPLACE BRAKE ACTUATOR ASSEMBLY (SKID CONTROL ECU)

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