The only way to know is to trace it out from the pump back to the front of the car. Unfortunately, inheriting somebody else's wiring mess can be a huge PITA.

 

Good morning fellow Lexus owner. This Morning I have been trying to see whats going on with my girl. Here is what I found.

I did the 12v mod and nothing changed. I thought it would be a good idea to leave it that way. So I moved over to the ecu. I unplugged the 40pin connector and the car started and turned off as it should. I then plugged the 40 pin connector back in and started the car. I turned the car off and the fuel pump stayed on. So, I now know that it is something connected to the small connector.

I notice when I had the small plug disconnected the idle was higher.

What do you think? what pins on the 40 pin connector control fuel or ignition?

 

Did you check pin 1 on the 40 pin like I said a few posts back? Also, I am very surprised the car even ran with the 40 pin unplugged. Are you positive the fuel pump was running with the 40 pin unplugged? How long did you run it without the 40 pin plugged in? The car may have idled higher because the pump was not running and it was pulling residual fuel from the rail causing a lean condition. Did you trace the wire out from the pump forward yet?

 

I suspect you have a mistake on the EFI relay circuit somewhere that is causing the relay to power itself in a loop once it is energized.

 

Once I pulled the 40 pin plug, The car ran for at least 30 sec to a minute. I pulled the 40 pin back in. I never checked to see if it would die from lack of fuel.
I did turn the car off and on with 40 pin unplugged. I did that a few times. This how I found out that the problem has to be at the 40 pin plug. The idle tone did change when I plugged 40 pin back in.

I did not trace the wire from pump. I thought that if it was working before, it has to have something wrong with the wiring.

 

which pins on the 40 pin would you suggest that I check first?

 

You are going to have to use the diagrams and go through the circuits one at a time to verify them. Start with the fuel pump and work back to the front of the car to find out where it is powered. Then, if you don't find the issue, start on the efi relay and what it feeds. If you are not able to trace/ohm/probe out a circuit with the diagrams you may have to take the car to a pro.

 

I got you!