Lexus RX (RX 350L, RX450h) 2016-2025 Repair Manual: Low Beam Headlight Circuit
DESCRIPTION
The main body ECU (multiplex network body ECU) controls the low beam headlights.
WIRING DIAGRAM
CAUTION / NOTICE / HINT
NOTICE:
- Inspect the fuses for circuits related to this system before performing the following procedure.
-
Before replacing the main body ECU (multiplex network body ECU), refer to Registration.
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PROCEDURE
| 1. | PERFORM ACTIVE TEST USING TECHSTREAM |
(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 / Main Body / Active Test.
(e) Perform the Active Test according to the display on the Techstream.
Body Electrical > Main Body > Active Test| Tester Display | Measurement Item | Control Range | Diagnostic Note |
|---|---|---|---|
| Headlight Relay | Low beam headlights | OFF/ON | - |
| Tester Display |
|---|
| Headlight Relay |
OK:
Low beam headlights illuminate.
| OK | .gif) | PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE |
|
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| 2. | INSPECT SEMICONDUCTOR POWER INTEGRATION ECU |
(a) Remove the semiconductor power integration ECU from the engine room relay block and junction block assembly.
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(b) Inspect the semiconductor power integration ECU.
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OK:
Semiconductor power integration ECU is normal.
| NG | | REPLACE SEMICONDUCTOR POWER INTEGRATION ECU |
|
| 3. | CHECK HARNESS AND CONNECTOR (POWER SOURCE - SEMICONDUCTOR POWER INTEGRATION ECU) |
(a) Measure the voltage according to the value(s) in the table below.
Standard Voltage:
| Tester Connection | Condition | Specified Condition |
|---|---|---|
| B-1 (BATT) - Body ground | Always | 11 to 14 V |
| NG | | REPAIR OR REPLACE HARNESS OR CONNECTOR |
|
| 4. | CHECK HARNESS AND CONNECTOR (SEMICONDUCTOR POWER INTEGRATION ECU - INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY) |
(a) Disconnect the 2C instrument panel junction block assembly connector.
(b) Measure the resistance according to the value(s) in the table below.
Standard Resistance:
| Tester Connection | Condition | Specified Condition |
|---|---|---|
| 1D-8 - 2C-31 | Always | Below 1 Ω |
| 1D-8 or 2C-31 - Body ground | Always | 10 kΩ or higher |
| NG | | REPAIR OR REPLACE HARNESS OR CONNECTOR |
|
| 5. | INSPECT INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY |
| *a | Component without harness connected (Instrument Panel Junction Block Assembly) | - | - |
(a) Remove the main body ECU (multiplex network body ECU) from the instrument panel junction block assembly.
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(b) Measure the resistance according to the value(s) in the table below.
Standard Resistance:
| Tester Connection | Condition | Specified Condition |
|---|---|---|
| 2C-31 - MB-15 (HRLY) | Always | Below 1 Ω |
| OK | | REPLACE MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU) |
| NG | | REPLACE INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY |
Taillight Relay Circuit
DESCRIPTION The main body ECU (multiplex network body ECU) controls the operation of the TAIL relay. WIRING DIAGRAM CAUTION / NOTICE / HINT NOTICE:
Inspect the fuses for circuits related to this s ...
High Beam Headlight Circuit
DESCRIPTION The main body ECU (multiplex network body ECU) controls the high beam headlights. WIRING DIAGRAM CAUTION / NOTICE / HINT NOTICE:
Inspect the fuses for circuits related to this system b ...
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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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