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I have an 03 GS300 that I swapped an Aristo engine/trans/harness/ecu into. Used the non immobilized ecu and the tweak'd performance jumper harness for the wiring.
The car runs great, makes great power, not having any issues. Went to hook my scanner to the car to look at some data and realized i have no communication with the PCM. I have power and ground at the port. Anyone run into this problem before i go deep diving into it? Thanks for any ideas.
Probably, your replacement ECU has a different pinout or a different wiring harness attachment to the vehicle for the OBD-II signals.
Unless it was modified (for non-immobilized) internally and some signals were disconnected from the connector.
Can you temporarily connect the original GS ECU to the car and check the OBD-II communication?
I found this message in the description of my diagnostic adapter (with Toyota Techstream) for Toyota / Lexus. Check this out. IMPORTANT! Always select the correct market (USA, Europe, Japan, etc.) as the same model (e.g. LEXUS GS300 '99) may use different protocols depending on the market. When the connection is established, the program should automatically recognize at least the engine type / model code. If this does not happen, then the market was probably chosen incorrectly.
Probably, your replacement ECU has a different pinout or a different wiring harness attachment to the vehicle for the OBD-II signals.
Unless it was modified (for non-immobilized) internally and some signals were disconnected from the connector.
Can you temporarily connect the original GS ECU to the car and check the OBD-II communication?
The pinouts are definately different, the tweakd harness was used to correct this. The ECU is an original non immobilized aristo ECU. The original GS ecu is long gone but communicated fine the day i swapped the car.
Your scanner would likely need to be programmed / set to support Japanese-spec ECU. I know that with my Torque app, very little was visible on the Aristo ECU. I found some help via Google back in the day to put in specific parameters and that allowed me to look at some data such as water temp, RPM, TPS and a few others. If my car was handy I'd plug in and tell you what I can see. It isn't. I do still have the settings in my torque app that I'd be happy to share, just cannot provide good context / reference for them, nor directly confirm what they offer in terms of functionality without my car handy.
What JOBD scanner do you have?
Can you check the continuity of the circuits from the vehicle's OBD-II port to the ECU connectors?
Below is the connection of the standard Lexus GS300 wiring for the OBD-II diagnostic connector.
OBD-II port, Description, ECU connector
--------------------------------------------------------------------------
Pin 4, Ground, Vehicle chassis
Pin 16, +12V, 7.5A OBD Fuse (driver side fuse box, left kick panel)
Pin 7, SIL (K-LINE), E6 - 11 -> most important for you, as communication line
Pin 13, TC (Timing check), E5 - 5
Pin 15, WFSE (L-LINE), E5 - 25 -> most important for you, as communication line
K Line - L Line Protocol. ISO 9141-2 and ISO/DIS 14230-4, Toyota / Lexus OBD-II used in most models after 1998.
The K signal is basically the medium for most communications through OBD-II.
The L signal is used for the initialization of the bus.
The maximum data rate is 10.4Kbps and maximum signal voltage is 12V.
K-Line is connected to Pin 7 and L-Line is connected to Pin 15 of the OBD-II port.
I checked the wiring diagrams of the 2JZ-GE LHD / RHD ECU regarding the OBD-II port and they are the same.
What year is your Aristo engine? Or what year of car was it taken from in Japan?
Here's some information about the communication protocols used by Toyota (Lexus) Co. over the years.
I bought an Ansel jp700.
Not 100% sure on the donor ecms year , I only know it runs the VVTi system and has no immobilizer.
I have the schematics for the aristo and for the gs300, just havent had the time to go through the jumper harness and check continuities to the ecm yet. was more wanting to make sure this wasnt a common thing before i dove in. hopefully when things slow down at the shop, ill have time to look into it.
2JZ-GTE was updated for the Japanese market in '97, when the engine received the VVT-i system. So all you know is that your engine is '97+. Based on my previous post about Japanese production years and communication protocols, it could be anything like SAE J1850-VPW in early models or ISO 1941-2 for later versions.
As you can see, they use different OBD-II port pins, so you need to check the continuity of both. And if your vehicle was manufactured for the North American market, the wiring harnesses may not have SAE J1850-VPW pins connected to the ECU.
10-10-23, 08:46 AM
03 GS300 aristo swap no scanner communication
