Lexus RX (RX 350L, RX450h) 2016-2025 Repair Manual: Engine Coolant Temperature Receiver Gauge Malfunction

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

DESCRIPTION

In this circuit, the combination meter assembly receives engine coolant temperature signals from the ECM via CAN communication. The combination meter assembly displays the engine coolant temperature that is calculated based on the data received from the ECM.

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.
  • Before replacing the ECM, refer to Registration.

    Click here

HINT:

  • If there is an open or short in the engine coolant temperature sensor circuit, the ECM stores DTCs. Troubleshoot the SFI system.

    Click here

  • Active Test cannot be performed on the engine coolant temperature receiver gauge 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 (WATER TEMPERATURE 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

Water Temperature Meter Operation

Engine coolant temperature receiver gauge

OFF, LOW, NORMAL, HIGH

-
Body Electrical > Combination Meter > Active Test

Tester Display

Water Temperature Meter Operation

OK:

Engine coolant temperature receiver gauge indication is normal.

NG

REPLACE COMBINATION METER ASSEMBLY

OK

4.

READ VALUE USING TECHSTREAM (COOLANT TEMPERATURE)

(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 / Data List.

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

Body Electrical > Combination Meter > Data List

Tester Display

Measurement Item

Range

Normal Condition

Diagnostic Note

Coolant Temperature

Engine coolant temperature

Min.: 0°C (32°F), Max.: 127.5°C (261.5°F)

75 to 100°C (167 to 212°F): After warming up engine

-
Body Electrical > Combination Meter > Data List

Tester Display

Coolant Temperature

OK:

Engine coolant temperature displayed on the Techstream is almost the same as the engine coolant temperature receiver gauge indication.

HINT:

  • When the Data List values and engine coolant temperature receiver gauge values match, a signal output malfunction of the ECM or an internal malfunction of the combination meter assembly is suspected.
  • When the Data List values and engine coolant temperature receiver gauge values do not match, an internal malfunction of the combination meter assembly is suspected.
NG

REPLACE COMBINATION METER ASSEMBLY

OK

5.

CHECK FOR DTC

(a) Check if SFI system DTCs are output.

Click here

Powertrain > Engine > Trouble Codes

Result

Proceed to

SFI system DTCs are not output.

A

SFI system DTCs are output.

B
B

GO TO SFI SYSTEM

A

6.

READ VALUE USING TECHSTREAM (COOLANT TEMP, COOLANT TEMPERATURE)

(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 Engine: Powertrain / Engine / Data List.

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

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

(1) Engine

Powertrain > Engine > Data List

Tester Display

Measurement Item

Range

Normal Condition

Diagnostic Note

Coolant Temperature

Engine coolant temperature

Min.: -40°C (-40°F), Max.: 140°C (284°F)

75 to 100°C (167 to 212°F): After warming up

This is the engine coolant temperature.

HINT:

  • After warming up the engine, the engine coolant temperature will be 75 to 100°C (167 to 212°F).
  • After a long soak, the engine coolant temperature, intake air temperature and ambient air temperature will be approximately equal.
  • If the value is -40°C (-40°F), or higher than 135°C (275°F), the sensor circuit is open or shorted.
  • Check if the engine overheats if the value indicated is higher than 135°C (275°F).
Powertrain > Engine > Data List

Tester Display

Coolant Temperature

(2) Combination Meter

Body Electrical > Combination Meter > Data List

Tester Display

Measurement Item

Range

Normal Condition

Diagnostic Note

Coolant Temperature

Engine coolant temperature

Min.: 0°C (32°F), Max.: 127.5°C (261.5°F)

75 to 100°C (167 to 212°F): After warming up engine

-
Body Electrical > Combination Meter > Data List

Tester Display

Coolant Temperature

Result

Proceed to

Data List values of the ECUs match.

A

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 ECM is suspected.
  • When the Data List values of the ECUs do not match, a signal output malfunction of the ECM or an internal malfunction of the combination meter assembly is suspected.
B

REPLACE ECM

A

7.

REPLACE COMBINATION METER ASSEMBLY

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

Click here

OK:

The operation of the engine coolant temperature receiver gauge returns to normal.

OK

END
NG

REPLACE ECM

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