Lexus RX (RX 350L, RX450h) 2016-2024 Repair Manual: Tachometer Malfunction
DESCRIPTION
In this circuit, the combination meter assembly receives engine speed signals from the ECM via CAN communication. The combination meter assembly displays the engine speed 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
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HINT:
Active Test cannot be performed on the tachometer 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 | .gif) | GO TO CAN COMMUNICATION SYSTEM |
|
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| 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 |
|
| 3. | PERFORM ACTIVE TEST USING TECHSTREAM (TACHOMETER 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 |
|---|---|---|---|
| TachoMeter Operation | Tachometer | OFF, 0, 1000, 2000, 3000, 4000, 5000, 6000, 7000 | - |
| Tester Display |
|---|
| TachoMeter Operation |
OK:
Tachometer indication is normal.
| NG | | REPLACE COMBINATION METER ASSEMBLY |
|
| 4. | READ VALUE USING TECHSTREAM (ENGINE RPM) |
(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 |
|---|---|---|---|---|
| Engine Rpm | Engine speed | Min.: 0 rpm, Max.: 12750 rpm | Almost the same as actual tachometer | - |
| Tester Display |
|---|
| Engine Rpm |
OK:
Engine speed displayed on the Techstream is almost the same as the tachometer indication.
HINT:
- When the Data List values and tachometer 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 tachometer values do not match, an internal malfunction of the combination meter assembly is suspected.
| NG | | REPLACE COMBINATION METER ASSEMBLY |
|
| 5. | CHECK FOR DTC |
(a) Check if SFI system DTCs are output.
Click here
| Result | Proceed to |
|---|---|
| SFI system DTCs are not output. | A |
| SFI system DTCs are output. | B |
| B | | GO TO SFI SYSTEM |
|
| 6. | READ VALUE USING TECHSTREAM (ENGINE SPEED, ENGINE RPM) |
(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 |
|---|---|---|---|---|
| Engine Speed | Engine speed | Min.: 0 rpm, Max.: 16383 rpm | 650 to 750 rpm: Idling (shift lever in N, engine warmed up and A/C off) | When the crankshaft position sensor is malfunctioning, "Engine Speed" is approximately 0 rpm or varies greatly from the actual engine speed. |
| Tester Display |
|---|
| Engine Speed |
(2) Combination Meter
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 | Almost the same as actual tachometer | - |
| Tester Display |
|---|
| Engine Rpm |
| Result | Proceed to |
|---|---|
| The Data List values of the ECUs do not match. | A |
| The Data List values of the ECUs 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 |
|
| 7. | REPLACE COMBINATION METER ASSEMBLY |
(a) Replace the combination meter assembly with a new one.
Click here
OK:
The operation of the tachometer returns to normal.
| OK | | END |
| NG | | REPLACE ECM |
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Lexus RX (RX 350L, RX450h) 2016-{YEAR} Owners Manual
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Lexus RX (RX 350L, RX450h) 2016-{YEAR} Repair Manual
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