4WD Control ECU Communication Stop Mode [10/2022 - ]: Procedure
WARNING: This page is about a different car, the 2025 Lexus RX 350, 2024 Lexus RX 350, and 2023 Lexus RX 350. However, it is still accessible from the selected car via links, so may be relevant.
- CHECK FOR OPEN IN CAN BUS LINES (4WD ECU ASSEMBLY BRANCH LINE)
- Disconnect the cable from the negative (-) battery terminal.
- Disconnect the H15 4WD ECU assembly connector.
- Measure the resistance according to the value(s) in the table below.
Standard Resistance
Tester Connection Condition Specified Value H15-17 (CANH) - H15-26 (CANL) Cable disconnected from negative (-) battery terminal 54 to 69 Ω Result
Proceed to OK NG
Result:
NG
REPAIR OR REPLACE CAN BRANCH LINES OR CONNECTOR (4WD ECU ASSEMBLY)
Result:
OK
See step 2
- CHECK HARNESS AND CONNECTOR (POWER SOURCE CIRCUIT)
- Disconnect the H14 4WD ECU assembly connector.
- Measure the resistance according to the value(s) in the table below.
Standard Resistance
Tester Connection Condition Specified Condition H14-1 (GND) - Body ground Cable disconnected from negative (-) battery terminal Below 1 Ω - Reconnect the cable to the negative (-) battery terminal.
- Measure the voltage according to the value(s) in the table below.
Standard Voltage
Tester Connection Switch Condition Specified Condition H14-24 (IG1) - Body ground Ignition switch ON 11 to 14 V H14-2 (BSLC) - Body ground Always 11 to 14 V Result
Proceed to OK NG
Result:
OK
REPLACE 4WD ECU ASSEMBLY. Refer to REMOVAL [10/2022 - ]
Result:
NG
REPAIR OR REPLACE HARNESS OR CONNECTOR (POWER SOURCE CIRCUIT)