Lexus Troubleshooting Questions? Ask a Lexus Expert
Hello. My name is ***** ***** I will be assisting you today. I see that you have replaced the brake switch, which was actually a good idea. Since you have checked the fuses and are still having the same issue, then the issue is going to either be the circuits for the 'stop signal' to the power source control ECU or the ECU itself is malfunctioning. In order to determine this, you will have to conduct some testing. The first step is to have the vehicle scanned with a capable scan tool, in order to retrieve the fault codes that is showing. There is a red and black wire that is coming from the brake switch to the ECU. This wire should have a signal when the brakes are pressed. Here, I am providing testing information for the issue that you are having. You will need a mutlimeter capable of measuring ohms and volts in order to perform the test provided. Also, a scan toll will be needed in order to check for fault codes. I have also provided the electrical circuits i order to give you a better idea of the system. This testing information will help you determine the root cause of the issue.
If you require more information on this issue and/or are not satisfied, let me know, please, and I will attempt to assist you further on this. I hope this information points you in the right direction. If you have any further questions or concerns on this issue, feel free to ask. If you are satisfied, and have found this information helpful, a positive rating would be greatly appreciated. Thank you.
A positive rating does not close the session. We will still be able to communicate and I will continue to assist you with this issue as needed.
If you are not getting a stop signal to the ECU, then the ECU will not signal the starter to start. Meaning you will not receive power to start. Here I am providing the electrical diagram for the starter circuit so that you can see the relation in the system. You can try checking the starter relay, in order to verify that it is functioning properly. Here, I am supplying the location information along with testing for the relay. Although, if the brake signal is not being sent, then the vehicle will not receive a start signal.
I am giving you information based on what you are telling me. Ultimately, as I stated earlier, you will have to have the vehicle scanned for trouble codes. These codes will give you the location of the area of concern. The information that I have provided is testing information that will help you pinpoint the issue. If the brake switch isn't sending a signal to the ECU, the vehicle will not start. If the security light is on, then the anti-theft module is likely not recognizing the key, all of these things should be taken into consideration. I am only providing information based on what I was told. I will have to advise you to have the vehicle scanned for fault/trouble codes in order to determine the issue. This is the most accurate way to determine the cause in your situation.