WOW! Thank you very much for this insight! It explains a LOT about how a manual IS300 showed up from 2002-2005 with but not before for 2001 even with VVT-i 2JZ-GE engines. It also fills in several gaps in how Toyota Japan handled late 90's model Supra NA manual cars.... they just didn't bother giving them VVT-i at all.

So with 707IS350's question a few days ago his son's 2001 GS300 which is equipped with an OBD2-A engine ECU can not just swap over (with wiring harness work) an '02-'05 IS300 M/T ECU.

I'm going to go out on a limb here and guess that his 2001 GS300, since it lacks a "Body ECU" for full CANBUS function will have a hard time swapping over both required '02+ M/T IS300 ECUs since the wiring for the "Body ECU" does not exist in a 2001 GS300. But it does in a 2002+ GS300 with a 2JZ-GE engine. Would that be correct?

 

Installed the original solenoids from the auto trans and connected to the vehicle. all the solenoid codes are gone. still have a Park Neutral switch code, need to send 12v to the "D" wire to let the computer known the vehicle is is Drive. Also getting a P0500 - Vehicle Speed Sensor Malfunction since the speed sensor is not in the transmission. still getting lack of power so I ordered the ATEMU.

Looking at the wiring diagram it looks like it may simulate the different speeds between input side and output side with torque converter lookup.

When ATEMU arrives the plan is to install it and the resistors inside the ecu box.

From https://www.serialnine.com/ original maker said to order from them as covid-19 would make delivery from Russia a nightmare.

Electronic Automatic Transmission Emulator for use when doing AT->MT swap and retaining AT ecu. When swapping VVT-i equipped cars the ECU will go into a semi-limp mode which will limit torque, power delivery characteristics and throttle response. The ATEMU will restore these characteristics back to stock level and give you the full potential of your manual transmisson swap. The difference is VERY noticable and you will be surprised at how much better your car feels after installing it. Installation takes approximately 1-2 hours depending on your wiring proficiency, the ATEMU gets wired into the AT plug at the ECU.

-Gets rid of Transmission related CEL's

-Restores throttle response

-Restores lack of torque

-Restores delayed power delivery when shifting

-Detailed instructions are included

-Shipping is included

 

so in addition to the ATEMU, what resistors are you using and what are the resistors supposed to solve exactly? Im planning to get my hands on a ATEMU in the next few days or so.

 

just for info, original maker is here but I can't change my nickname
tech support: https://all4swap.ru/contact
atemu: https://all4swap.ru/product/atemu
no resistors required normally. The device ensures rated factory torque, mpg and stable idle that's what it does, nothing else no coffee making no ********** just that
Also, 3UZ and 2GR ecus can be reprogrammed for m/t . Only older ecus need ATEMU for proper operation without stock a/t

 

When I tried to get all the codes off with an auto ecu and manual swap in my tacoma, resistors and stuff was easy and could get rid of every code except for the second vss (one inside the auto trans that tells speed with relation to the gear you are in).
I then mounted a second vss and a trigger wheel on the driveshaft to simulate the second vss (4 tooth rotor), which made the ecu happy till you get on the highway, and if you are in a different gear than what the auto ecu thinks you should be in, you get a code for ratio mismatch from the second vss to the first vss.

So what was really needed instead of putting in a makeshift second vss, was to simulate the second vss off of the main vss (actual speed) and the gear output by the ecu (times whatever ratio the automatic gears are for that ecu), so the second vss will always follow the first vss time the gear ratio. that way the ecu would always think the trans is in the right gear and working.

I did not feel like it was worth making the circuit since I could swap to a manual ecu in that car, but for other cars it would be helpful, and I am guessing that is what they are doing on that device above. cause all the solenoids and stuff are easy just put in the right resistor, but that second vss and the ratio mismatch are the final codes you need to get passed once you get far enough down the process. hope that provides some insight for those wanting to get it working, it needs to address the second vss.. the solenoid resistors are super easy and not the main issue.

 

Installed the ATEMU. All codes gone including the 2nd VSS so no more P0500 as the ATEMU emulates that signal to the AT ECU. It also emulated shifting the auto shifter. at idle it is emulated in "P", of idle it shifts to "2" (normally but instructions stated the "L" might work better so installed ATEMU "2" to A/T ECU "L". We are still running the original solenoids in a zip lock bag for testing purposes as car is still acting up. (once fixed will remove and install the resistors) My son said car feels better with the ATEMU but still not 100%. On his last test drive we got some misfire codes. I believe something else is wrong with the car. Planing on diagnosing tomorrow.

 

Good to hear im interested to hear an update!

 

I have 98 VVTI with a manual swap. I have the solenoids hooked up, the ECU is always in neutral. No codes. But I dont use cruise control. As far as driving characteristics I cant feel any difference in performance or fuel economy. Is there supposed to be a "semi-limp" mode?

 

Rechecked the GS300 yesterday and tried the other info ATEMU instructions provided, (e.i Swapped ATEMU "2" to ECU "2", Tried different modes from the ATEMU, and Tried to disconnect SP2+(this made P0500 come back)) Vehicle still feels bad. Brought my Toyota Scan Tool home and drove around while recording live data. Looks like its running lean on both banks. So next step is to find a other MAF sensor to swap(already cleaned) and check fuel pressure. Other than that all codes are gone but the Park Neutral Switch code comes back sometimes. I think because the ATEMU receives a higher than 800 rpm signal from Crankshaft Speed Signal(RPM) while engine is warming up(warm up mode/idle up) the ATEMU switches to "2" too early triggering the PN switch code. Once the engine is at operating temp the idle speed is lower than 800 rpm so the ATEMU stays in "P" mode so no code. The PN switch code is a 2 trip detection code meaning the ECU needs to see this code 2 twice in a row on the next start up. I believe if the car was running right from the lean condition then the code would clear it self before the next startup under normal driving around.

 

From experience on other Toyota vehicle they do have a limp mode when the ECU detects something wrong with the AT( Automatic Transmission) usually it makes the transmission stuck in second gear to get you off the road safely but not every computer will go in to limp mode the same way as a different car. Possible the issues we have been having may have been the engine not running properly due to fueling issues and not the missing AT signals. I will try removing the ATEMU once I get the car running right to see the difference. I still think with the ATEMU it may be possible to pass the California Emissions test on the Check engine light on portion of the test and I don't think that the Manual swap it self would fail it.

 

Turned out the Catalytic Converter are clogged. Removed both the front A/F sensors front the exhaust manifolds test drove it and full power is back now. Plan is to now hollow out the Cats.

 

Hollowed out all 3 Catalytic Converters. removed solenoids and installed resistors. SLN resistors got very hot. ATEMU recommends resistors of 10 Ohms and 25 Watts with heat sink. Managed to wire up multiple resistors to divide up the wattage and keep the resistors cooler that way. His been driving it for a little bit as Covid has closed DMV to get the car registered. No Check Engine Light coming on. Car is running great.

 

Would you be able to take pictures of the wires where you wired in the ATEMU and resistors into the ecu? I really want to do the swap on my 2000(live in California) and want to see exactly how you did it. Its great that your SC is running great after the work you did, way better that taking apart an auto trans or the solenoids. Thank you for your work!

 

2nd this as Im trying got get the guts to try this on my 2000 sc400. Looking to install the Collins CD009 kit.

 

It is the most significant of bummers to reach the end of this thread with no resolution from a year ago. 🥲 I am finishing my swap and need to wire the resistors and ATEMU, and most of these threads/YouTube videos fizzle out or skim over this last crucial part. Anybody have any updates/photos/insight on wiring for 98+ SC400s?