I’ve used this board previously for answers and would like to say thank you!
My first post is a doosie. I’ll try to keep it concise as possible.
I have a 2003 is300 5 spd. I replaced the old motor (rod knock on 2 cyl) with a rebuilt Ge, straight switch. Everything went smooth. Went to start, turns over strong. However the immobilizer is tripped, it has no spark, and the dlc can not communicate to the ecu.
The only key I have is the valet key, but that shouldn’t matter from what I understand.
The dlc has power, turns on the odb scanner, it can’t connect to the ECU.
ive checked every single fuse…everyone. All are in working order.
checked all connectors, even re attached some grounds to make sure that wasn’t it. Still the same issues.
We used the original engine harness and ecu.
Thought it was the ecu, got a replacement. No matter same issues.
Tried to reset the ecu, did nothing.
What was supposed to take a week or so at night in my garage has spilled in to 3 weeks and I’m frustrated as F now.
I was hoping the board may have some suggestions. My father and I have gone over schematics many times looking for a break in the harness? Looked for all grounds and junctions where my 3 problems may overlap…still coming up short.
thank you in advance for any help or suggestions. I could really use some.

 

I don't think your immobilizer is tripped - I think your antitheft was tripped. I think you need to turn the antitheft off.
The only way I know that works for that is hitting the unlock button on the master key 3 times in a row.
If you only have the valet key, the immobilizer was not tripped because that chip matches the ecu.

I think you need to put back the original ecu and figure out a way to turn off the antitheft using only the valet key.

 

Does the theft deterrent system, when tripped, turn off spark, communication to the ecu from the dlc port?

 

The antitheft ecu disables the whole car. It is a separate ecu located within the car. I don't know if it would disable the OBD2 port tho

 

To follow up:

We weren’t getting the readings we wanted from the ecu/engine harness. We said F it. We cut wire E4 35 blue yellow 5v. As soon as we did that the DLC could talk to the ecu and we were able to get a set of codes. From there we traced to back to the power steering switch/sensor! I’ve ordered a new sensor and I’m going to get a new battery as well. It also resolved the immobilizer being tripped. I have a lot to put back together. We also have spark now.
Thank you to everyone who took time to respond.

 

It does not. that is 100% incorrect information.
The immobilizer system and the security systems are completely separate.

The security system only covers entry into the vehicle, and has nothing to to with the immobilizer system. The immobilizer system only has to do with the engine/ECU itself. When activated it disables ignition and in some lexus vehicles fuel as well.

With that said I can pair a new key, and disable the immobilizer system along with tuning the ecu and remapping the automatic transmission to perform much better.


https://quantum-auto.com/ols/product...re-map-service


https://quantum-auto.com/ols/product...ecu-re-map-srv