Power Source Mode does not Change to ON (ACC) [09/2023 - ]: Procedure
WARNING: This page is about a different car, the 2024 Lexus TX 550h+ and 2024 Lexus TX 500h. However, it is still accessible from the selected car via links, so may be relevant.
- CHECK FOR DTC
- Using the GTS, check for certification ECU (smart key ECU assembly) DTCs.
Body Electrical > Power Source Control > Trouble Codes
Body Electrical > Smart Access > Trouble Codes
Result
Result Proceed to DTCs are not output A Smart access system with push-button start (for Start Function) DTCs are output B
Result:
B
GO TO DIAGNOSTIC TROUBLE CODE CHART. Refer to DIAGNOSTIC TROUBLE CODE CHART [09/2023 - 12/2023] , or refer to DIAGNOSTIC TROUBLE CODE CHART [12/2023 - ]
Result:
A
See step 2
- Using the GTS, check for certification ECU (smart key ECU assembly) DTCs.
- CHECK HARNESS AND CONNECTOR (POWER DISTRIBUTION BOX ASSEMBLY - POWER SOURCE)
- Disconnect the B55 power distribution box assembly connector.
- Measure the voltage according to the value(s) in the table below.
Standard Voltage
Tester Connection Condition Specified Condition B55-1 - Body ground Ignition switch off 11 to 14 V Result
Proceed to OK NG
Result:
NG
REPAIR OR REPLACE HARNESS OR CONNECTOR
Result:
OK
See step 3
- CHECK POWER DISTRIBUTION BOX ASSEMBLY (ACC RELAY)
- Remove the power distribution box assembly.
Refer to REMOVAL [09/2023 - ]
- Remove the main body ECU (multiplex network body ECU) from the power distribution box assembly.
- Connect the auxiliary battery terminal (+) to the D62-38 terminal.
- Connect the auxiliary battery terminal (-) to the D62-36 terminal.
*a Component without harness connected
(Power Distribution Box Assembly)- - - Measure the resistance according to the value(s) in the table below.
Standard Resistance
Tester Connection Condition Specified Condition B55-1 - D62-12 Auxiliary battery voltage applied between terminals D62-38 and D62-36 Below 1 Ω Result
Proceed to OK NG
Result:
OK
REPAIR OR REPLACE HARNESS OR CONNECTOR
Result:
NG
REPLACE POWER DISTRIBUTION BOX ASSEMBLY. Refer to REMOVAL [09/2023 - ]
- Remove the power distribution box assembly.