Lexus NX: Problem Symptoms Table
PROBLEM SYMPTOMS TABLE
HINT:
- Troubleshooting of the theft deterrent system is based on the premise that the power door lock control system and the wireless door lock control system are operating normally. Accordingly, before troubleshooting the theft deterrent system, first make certain that the power door lock control system and the wireless door lock control system are operating normally.
- 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 theft deterrent system cannot be set or canceled | Proceed to immobiliser system "Security Indicator Light Does not Blink" | |
| ACC signal circuit | | |
| IG signal circuit | | |
| Door unlock detection switch circuit | | |
| Door courtesy switch circuit | | |
| Back door courtesy switch circuit | | |
| Engine hood courtesy switch circuit | | |
| Back door opener switch assembly | | |
| Harness or connector | - | |
| If the symptom(s) still occur after the above area is inspected and proved to be normal, replace the main body ECU (multiplex network body ECU) | | |
| After a wireless door lock operation is performed with the back door open, the theft deterrent system is not set when the back door is closed | Proceed to immobiliser system "Security Indicator Light Does not Blink" | |
| ACC signal circuit | | |
| IG signal circuit | | |
| Door unlock detection switch circuit | | |
| Door courtesy switch circuit | | |
| Back door courtesy switch circuit | | |
| Engine hood courtesy switch circuit | | |
| Back door opener switch assembly | | |
| Harness or connector | - | |
| If the symptom(s) still occur after the above area is inspected and proved to be normal, replace the main body ECU (multiplex network body ECU) | | |
| After a wireless door lock operation is performed with the hood open, the theft deterrent system is not set when the hood is closed | Proceed to immobiliser system "Security Indicator Light Does not Blink" | |
| ACC signal circuit | | |
| IG signal circuit | | |
| Door unlock detection switch circuit | | |
| Door courtesy switch circuit | | |
| Back door courtesy switch circuit | | |
| Engine hood courtesy switch circuit | | |
| Back door opener switch assembly | | |
| Harness or connector | - | |
| If the symptom(s) still occur after the above area is inspected and proved to be normal, replace the main body ECU (multiplex network body ECU) | | |
| Security indicator light does not blink when theft deterrent system is set | Proceed to immobiliser system "Security Indicator Light Does not Blink" | |
| The theft deterrent system becomes set by itself | Check customize setting | |
| Door courtesy switch circuit | | |
| Back door courtesy switch circuit | | |
| Engine hood courtesy switch circuit | | |
| If the symptom(s) still occur after the above area is inspected and proved to be normal, replace the main body ECU (multiplex network body ECU) | | |
| The theft deterrent system cannot be canceled by turning the power switch on (IG) | Main body ECU (multiplex network body ECU) | |
| None of the alarm functions operate or the theft deterrent system can be set even when all necessary conditions are not met | Door unlock detection switch circuit | |
| Door courtesy switch circuit | | |
| Back door courtesy switch circuit | | |
| Engine hood courtesy switch circuit | | |
| If the symptom(s) still occur after the above area is inspected and proved to be normal, replace the main body ECU (multiplex network body ECU) | | |
| The doors are not forcibly locked when the vehicle is in the alarm sounding state | Smart access system with push-button start (for Entry Function) | |
| Wireless door lock control system | | |
| Door unlock detection switch circuit | | |
| If the symptom(s) still occur after the above area is inspected and proved to be normal, replace the main body ECU (multiplex network body ECU) | | |
| The vehicle does not enter the alarm sounding state when the auxiliary battery is reconnected while the vehicle is in the armed state | Check operation of the security indicator light | |
| If the symptom(s) still occur after the above area is inspected and proved to be normal, replace the main body ECU (multiplex network body ECU) | | |
| The vehicle does not enter the alarm sounding state when the back door is opened while the vehicle is in the armed state | Check operation of the security indicator light | |
| Back door courtesy switch circuit | | |
| If the symptom(s) still occur after the above area is inspected and proved to be normal, replace the main body ECU (multiplex network body ECU) | | |
| The vehicle does not enter the alarm sounding state when the hood is opened while the vehicle is in the armed state | Check operation of the security indicator light | |
| Engine hood courtesy switch circuit | | |
| If the symptom(s) still occur after the above area is inspected and proved to be normal, replace the main body ECU (multiplex network body ECU) | | |
| The vehicle does not enter the alarm sounding state when the doors are unlocked while the vehicle is in the armed state | Door unlock detection switch circuit | |
| Door courtesy switch circuit | | |
| Back door courtesy switch circuit | | |
| If the symptom(s) still occur after the above area is inspected and proved to be normal, replace the main body ECU (multiplex network body ECU) | | |
| The security horn assembly does not operate when the vehicle is in the alarm sounding state (w/ Security Horn Assembly) | Security horn circuit | |
| The theft warning siren assembly does not operate due to the auxiliary battery being disconnected when the vehicle is in the alarm sounding state (w/o Security Horn Assembly) | Theft warning siren circuit | |
| The hazard warning lights do not operate when the vehicle is in the alarm sounding state | Combination meter assembly | |
| If the symptom(s) still occur after the above areas are inspected and proved to be normal, replace the main body ECU (multiplex network body ECU) | | |
| The vehicle horn does not operate when the vehicle is in the alarm sounding state | Horn circuit | |
| Hazard warning lights flash even when theft deterrent system is not set | Combination meter assembly | |
| If the symptom(s) still occur after the above areas are inspected and proved to be normal, replace the main body ECU (multiplex network body ECU) | |
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