Problem Symptoms Table [10/2015 - 12/2017]

WARNING: This page is about a different car, the 2017 Lexus RX 450h and 2016 Lexus RX 450h. However, it is still accessible from the selected car via links, so may be relevant.

NOTE:

Before replacing the hybrid vehicle control ECU assembly, refer to Registration.

Refer to REGISTRATION [10/2015 - 08/2019]

HINT:

Use the table below to help determine the cause of problem symptoms. If multiple suspected areas are listed, the potential causes of the symptoms are listed in order of probability in the "Suspected Area" column of the table. Check each symptom by checking the suspected areas in the order they are listed. Replace parts as necessary.
Inspect the fuses and relays related to this system before inspecting the suspected areas below.

Symptom	Suspected Area	Link
The cruise control system cannot be turned on using the cruise control main switch (ON/OFF button) (The cruise control indicator does not illuminate)	CAN communication system	Refer to HOW TO PROCEED WITH TROUBLESHOOTING [10/2015 - 08/2019]
	Cruise control indicator light circuit	Refer to Cruise Main Indicator Light Circuit [10/2015 - 12/2017]
	Cruise control switch circuit	Refer to Cruise Control Switch Circuit [10/2015 - 12/2017]
	Combination meter assembly	Refer to REMOVAL [10/2015 - 08/2016] , or refer to REMOVAL [08/2016 - 03/2018]
	Hybrid vehicle control ECU assembly	Refer to REMOVAL [10/2015 - 08/2016] , or refer to REMOVAL [08/2016 - 03/2018]
The cruise control SET indicator does not illuminate (Vehicle speed can be set)	CAN communication system	Refer to HOW TO PROCEED WITH TROUBLESHOOTING [10/2015 - 08/2019]
	Cruise SET indicator light circuit	Refer to Cruise SET Indicator Light Circuit [10/2015 - 12/2017]
	Combination meter assembly	Refer to REMOVAL [10/2015 - 08/2016] , or refer to REMOVAL [08/2016 - 03/2018]
	Hybrid vehicle control ECU assembly	Refer to REMOVAL [10/2015 - 08/2016] , or refer to REMOVAL [08/2016 - 03/2018]
Vehicle speed cannot be set (The cruise control indicator illuminates when the cruise control system is turned on using the cruise control main switch (ON/OFF button), but the cruise control indicator turns off when the cruise control main switch is pushed to -SET)	Cruise control switch circuit	Refer to Cruise Control Switch Circuit [10/2015 - 12/2017]
	Hybrid vehicle control ECU assembly	Refer to REMOVAL [10/2015 - 08/2016] , or refer to REMOVAL [08/2016 - 03/2018]
Vehicle speed cannot be set (The cruise control indicator illuminates when the cruise control system is turned on using the cruise control main switch (ON/OFF button), and it remains illuminated when the cruise control main switch is pushed to -SET)	Inspect the fail-safe control list	Refer to FAIL-SAFE CHART [10/2015 - 12/2017]
	CAN communication system	Refer to HOW TO PROCEED WITH TROUBLESHOOTING [10/2015 - 08/2019]
	Cruise control switch circuit	Refer to Cruise Control Switch Circuit [10/2015 - 12/2017]
	Stop light switch circuit	Refer to DTC P0571: Brake Switch "A" Circuit [10/2015 - 12/2017]
	Hybrid control system	Refer to HOW TO PROCEED WITH TROUBLESHOOTING [10/2015 - ]
	Electronically controlled brake system	Refer to HOW TO PROCEED WITH TROUBLESHOOTING [10/2015 - 08/2018]
	Combination meter assembly	Refer to REMOVAL [10/2015 - 08/2016] , or refer to REMOVAL [08/2016 - 03/2018]
	Hybrid vehicle control ECU assembly	Refer to REMOVAL [10/2015 - 08/2016] , or refer to REMOVAL [08/2016 - 03/2018]
Vehicle speed control by the cruise control system is automatically canceled after it has started	Inspect the fail-safe control list	Refer to FAIL-SAFE CHART [10/2015 - 12/2017]
	CAN communication system	Refer to HOW TO PROCEED WITH TROUBLESHOOTING [10/2015 - 08/2019]
	Cruise control switch circuit	Refer to Cruise Control Switch Circuit [10/2015 - 12/2017]
	Stop light switch circuit	Refer to DTC P0571: Brake Switch "A" Circuit [10/2015 - 12/2017]
	Hybrid control system	Refer to HOW TO PROCEED WITH TROUBLESHOOTING [10/2015 - ]
	Electronically controlled brake system	Refer to HOW TO PROCEED WITH TROUBLESHOOTING [10/2015 - 08/2018]
	Hybrid vehicle control ECU assembly	Refer to REMOVAL [10/2015 - 08/2016] , or refer to REMOVAL [08/2016 - 03/2018]
Hunting (Speed is not constant)	Hybrid control system	Refer to HOW TO PROCEED WITH TROUBLESHOOTING [10/2015 - ]
	SFI system	Refer to HOW TO PROCEED WITH TROUBLESHOOTING [10/2015 - ]
	Hybrid vehicle control ECU assembly	Refer to REMOVAL [10/2015 - 08/2016] , or refer to REMOVAL [08/2016 - 03/2018]
Pulling back on the cruise control main switch does not cancel vehicle speed control by the cruise control system	Cruise control switch circuit	Refer to Cruise Control Switch Circuit [10/2015 - 12/2017]
	Hybrid vehicle control ECU assembly	Refer to REMOVAL [10/2015 - 08/2016] , or refer to REMOVAL [08/2016 - 03/2018]
Vehicle speed control by the cruise control system is not canceled when the vehicle speed drops below the low speed limit	Electronically controlled brake system	Refer to HOW TO PROCEED WITH TROUBLESHOOTING [10/2015 - 08/2018]
	Hybrid vehicle control ECU assembly	Refer to REMOVAL [10/2015 - 08/2016] , or refer to REMOVAL [08/2016 - 03/2018]
Moving the shift lever does not cancel vehicle speed control by the cruise control system	Shift lever position sensor	Refer to REMOVAL [10/2015 - 08/2019]
	Transmission floor shift assembly	Refer to REMOVAL [10/2015 - ]
	Hybrid vehicle control ECU assembly	Refer to REMOVAL [10/2015 - 08/2016] , or refer to REMOVAL [08/2016 - 03/2018]
Vehicle speed control by the cruise control system is not canceled when paddle shift switch is operated	Transmission shift switch circuit	Refer to Shift Paddle Switch Circuit [10/2015 - ]
	Hybrid vehicle control ECU assembly	Refer to REMOVAL [10/2015 - 08/2016] , or refer to REMOVAL [08/2016 - 03/2018]
Depressing the brake pedal does not cancel vehicle speed control by the cruise control system	Stop light switch circuit	Refer to DTC P0571: Brake Switch "A" Circuit [10/2015 - 12/2017]
	Hybrid vehicle control ECU assembly	Refer to REMOVAL [10/2015 - 08/2016] , or refer to REMOVAL [08/2016 - 03/2018]