Lexus Troubleshooting Questions? Ask a Lexus Expert
Can you please clarify the current situation? Is the engine still continuing to crank over and not starting up? Do you have the traditional key or push button start system? Why was the engine control computer replaced? Will a code reader read any malfunction codes from the engine control computer?
Did you check all the fuses to make sure none of the fuses are blown? Did you replace the ECU with a used or new one? When you replaced the ECU did you do the handshake to establish the communication between the transponder ECU and the engine control computer?
In the diagnostic port where you plug the scan tool in you need to identify terminals CG and TC. Install a jumper wire between these two pins I don't remember the pin numbers and I don't have access to a pin chart at this time. Once the jumper wires installed turn the key to the on position to start a timer for exactly 30 minutes. Once the 30 minutes has elapsed turn the key off or shut the start button off and remove the jumper wire. Then see if it will start.
This will get really complicated especially if it was jump backwards let me know how things go I will make a decision at that time.
Will the scan tool interface with the ECM?
Can you check the voltage to all of the fuses in the fuse block under the hood? Let me know which fuses are not getting 12 V. Just to clarify you're saying that the scan tool will not communicate with the network when you plug it in?
Unfortunately this problem is probably a bit deeper than what we can handle this type of format. This is going to be a hands-on type repair. I will opt out so that if there are other experts that have run into the specific problem they may be able to assist you further.