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still no answers on auto tranny issues
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Offline 1uz4runner

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still no answers on auto tranny issues
« on: January 15, 2007, 11:21:04 PM »
I have an a340h 94 4runner and i thinking to use everything inside the sc400 tranny (bh,tc,fp,vb) and try to use my case and transfer case. I hear there is an issue with speedo's and silanoids and ive gotta elec speedo so it might work any update cebby?

Offline toylexus

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Re: still no answers on auto tranny issues
« Reply #1 on: February 02, 2007, 01:07:36 AM »
Hey, i'm in process of doing a 1UZ swap from a '95 SC400 into a '94 4runner. Right now i'm working on fitting the front input speed sensor from the lexus into the toyota transmission. (It is a 4WD truck). I'm drilling out the casting on the side of the case to fit the sensor into the toyota trans. That part should be done soon. After that i'll be looking inside the lexus trans at the shift solenoids. i'll post what i find when i figure it out. 

Offline Cebby

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Re: still no answers on auto tranny issues
« Reply #2 on: February 02, 2007, 05:36:34 AM »
toylexus is on the right track.  That casting boss and knockout on the case needs to be utilized.

As far as the shift solenoids, I need to go back through my build thread to see what i had discovered a while back - I know the stock ECU is expecting more solenoids than the A340H has, but if memory serves, one was a shift quality solenoid that did not need to be hooked up.  Can't remember what else without going back and researching.
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Offline toylexus

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Re: still no answers on auto tranny issues
« Reply #3 on: February 03, 2007, 03:30:31 AM »
I succesfully installed the input speed sensor (ISS) on the left side of the A340H transmission. The final drill bit size was a 37/64". It was just a little small, but careful movement of the bit opened up the hole just perfectly. The sensor went in without any trouble. As for the solenoids in the A341E trans, i removed the oil pan and inspected today.

There is a pass-thru connector with 8 pins in it on the outside of the case. There are 2 shift solenoids. Each shift solenoid has a 1-wire connector attached to it. The number 3 solenoid is TCC lockup solenoid with a 2-wire connector, and the number 4 solenoid is the line pressure/shift quality solenoid also with a 2-wire connector.  There is also what appears to be a transmission fluid temp. sensor with 2 orange wires connected to it attached to a shift solenoid bolt.

The differences that caught my eye I verified on the transmission control schematics; the A340H (toyota) transmission only has 3 wires going into the transmission from the pass-thru connector. There are 3 solenoids with a 1-wire connector attached inside. They are: shift solenoid 1, shift solenoid 2, and the TCC lockup solenoid. My concern is with the TCC solenoid. In the lexus trans (A341E), the TCC is a Pulse-width modulated (PWM) controlled solenoid, which means the computer can accurately control the on/off time, or duty cycle, of this solenoid very quickly. Hence the 2 wires. In the toyota trans, the computer simply turns the solenoid on or off. Hence the 1 wire. The TCC solenoid in the toyota may not be able to stand up to the constant on/off cycling from the lexus transmission controller if it were connected. 

I'm going to see if the TCC solenoid from the Lexus trans will fit in the valve body of the toyota. The TCC solenoid in the lexus appears to be bigger in size than the one in the toyota. I hope this info helps. I'll post more as I go. 

Offline milano

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Re: still no answers on auto tranny issues
« Reply #4 on: February 03, 2007, 01:51:00 PM »
The '95 SC400 is obd2. If you don't use the Lexus valve body with the four solenoids, the ecm will turn on the check engine light.
 The a341e transmission will attach to the Toyota transfer case if you take both transmissions appart and swap the output shafts.
 This sounds complicated but is not hard at all if you take your time and keep things clean and organized. You will need to install that reluctor ring and speed sensor from the Lexus output shaft.
I did this with a two wheel drive 4runner and it works perfectly. If you need pictures of the transmission you can purchase an ATSG book on the a340/a341 for about $15 online or from a transmission shop. These books are really helpfull.

Offline toylexus

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Re: still no answers on auto tranny issues
« Reply #5 on: February 03, 2007, 08:34:32 PM »
Let's keep things clear here: OBD II was not implemented until 1996. The 1995 SC400's powertrain diagnostic chart consists of two digit codes (example: code 12, code 22, code 24) whereas ALL OBD II codes are designated as powertrain with a "P" followed by a four digit number (example: P0305, P0440). And the 1995 SC400 also does not have the Global OBD II connector under the dash. 

Offline toylexus

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Re: still no answers on auto tranny issues
« Reply #6 on: February 08, 2007, 12:51:36 AM »
"The '95 SC400 is obd2. If you don't use the Lexus valve body with the four solenoids, the ecm will turn on the check engine light.
 The a341e transmission will attach to the Toyota transfer case if you take both transmissions appart and swap the output shafts."

-------------------------------------------------------------------------------------------------------------------------------------------------------------
I confirmed in the clean air course i'm taking right now that a transmission related code will not cause a vehicle to fail a smog test. <EDIT> This only applies to an OBD I vehicle. i did confirm that an OBDII vehicle WILL fail the functional test if a shift solenoid or related transmission (auto only) component sets a code that turns on the check engine light. There's some more info in the Exhaust, Cats, and Mufflers thread--  A Few Words on OBD II and Smogchecks.
I have also verified with visual inspection of both the A341E and A340H transmissions side by side that an A341E WILL NOT connect to a transfer case from an A340H. The valve body in the toyota (A340H) has metal fluid lines connected between it and the transfer case. The lexus valve body covers the ports where the lines would pass through to the transfer case. The lexus (A341E) valve body itself also does not have any fluid ports for these metal lines to connect to as the toyota valve body does.

Further inspection on the lexus TCC solenoid shows that it is about 2 inches longer than the TCC solenoid in the toyota. That means it won't transfer over. In an effort to further understand how PWM TCC works, i'm going to play around with a scan tool on my own vehicle and get into the transmission controls.

My concern there is that the lexus ecu is going to control any TCC solenoid connected to it in pulse-width. That could mean a shaky ride when the solenoid engages. On the flip side, the lexus torque convertor is being used on the toyota transmission, so the rapid cycling of the TCC solenoid may not affect the lexus convertor as much as it would the toyota convertor. Just thinking out loud.
« Last Edit: June 30, 2007, 04:53:36 PM by toylexus »

Offline Cebby

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Re: still no answers on auto tranny issues
« Reply #7 on: February 08, 2007, 10:53:48 AM »
Does anyone know how the Tundra ECU and trans handle the TCC solenoid?  Is it the same as the Lexus? 

The guy I bought a Tundra trans ouput, TC, tailhousing and bell from might have some pics from when he took his "grenaded" trans apart.... 

Let me see if I can find his info.
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Offline toylexus

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Re: still no answers on auto tranny issues
« Reply #8 on: February 09, 2007, 09:28:50 AM »
i got a slightly better understanding of tcc yesterday. i did play around with the tcc in my xuv. i know it's a GM, but the basic operation of tcc is the same. It utilizes a PWM solenoid as well. i could drive it with a scan tool connected and watch the ecu control the % of duty cycle to the tcc. i did mostly 35-50 mph driving. I believe that it is mostly a fuel economy feature, allowing the torque converter to lock up like a clutch in a manual transmission, eliminating torque converter slip at higher speeds.  Also, going to a PWM solenoid (in GM's case anyway) allows for slippage of the tc clutch itself for a smoother engagement. They said in a description and operation i read that it helps eliminate vibration and "chuggle". i observed this, at about 50 mph the tcc was on but only operating at 37% duty cycle. it also showed about a 20-100 rpm tcc clutch slip at that point. Very interesting.

I also got into the tcc controls. it would let me turn it on/off, but not control duty cycle, which IS possible even on a PWM controlled solenoid. When i turned it on at lower speeds i could feel the 'thump' when it engaged (100% duty cycle). There was a noticeable drop in rpm and it felt like i was driving a manual transmission at 35 mph in 5th gear. i took a data recorder home and took 4 snapshots of 4 different driving conditions last night. if anyone is interested i'll post what i find. i'm going to review that data today.

Coming down to it, my thought on this whole tcc situation is to leave the toyota tcc solenoid in the transmission. The solenoid will need to be isolated from case/chassis ground so that the lexus ecu can control the solenoid ground circuit. That means once the solenoid IS isolated from ground, connect the lexus power wire to the solenoid connector, and solder the lexus ground control circuit to the solenoid case. Then, make the wiring connection outside of the transmission so that both wires can be unplugged and rewired as needed from outside the transmission if something doesn't work right using the PWM controls on the on/off solenoid.
« Last Edit: February 09, 2007, 09:35:00 AM by toylexus »

Offline Cebby

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Re: still no answers on auto tranny issues
« Reply #9 on: February 09, 2007, 12:29:22 PM »
That is great tech!  We certainly would love to see the pics.

BTW, I sent a PM to the guy I bought the Tundra trans parts from - hopefully he can shed some light on this also.
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Offline toylexus

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Re: still no answers on auto tranny issues
« Reply #10 on: February 09, 2007, 02:54:12 PM »
i'm still a little new to posting pictures, so once i figure it out (hopefully very soon!) i'll start putting up all the pictures i've been taking.

Offline Cebby

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Re: still no answers on auto tranny issues
« Reply #11 on: February 09, 2007, 03:05:23 PM »
You can use the gallery here on the site (see menu above) to post pics or use the image attachment feature.
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Offline toylexus

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Re: still no answers on auto tranny issues
« Reply #12 on: February 09, 2007, 08:09:20 PM »


This is the '94 4runner getting the 1UZ that i'm working on. (this is also a test pic)

Offline toylexus

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Re: still no answers on auto tranny issues
« Reply #13 on: February 09, 2007, 08:23:31 PM »


This is the underside of the lexus transmission, oil pan removed. Note the 4 solenoids.



This is the underside of the toyota transmission, oil pan removed. Note 3 solenoids and the metal lines on the right side.



Wire pass-thru on the lexus (8 wires total)



Wire pass-thru on the toyota (3 wires total)



These metal lines are why the lexus transmission won't attach to the A340H transfer case. Clearance and valve body issues.



This is what appears to be the trans. fluid temp sensor.



This is the lexus TCC solenoid. The end piece coming off the solenoid sticks out 2".



This is the toyota TCC solenoid (on/off type).



This is the toyota transmission, before drilling out the hole for the input speed sensor.



Lexus input speed sensor succesfully installed on the toyota.



Panned out, showing it is the A340H the input speed sensor is attached to now :)

Offline toylexus

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Re: still no answers on auto tranny issues
« Reply #14 on: February 12, 2007, 01:20:52 AM »
I know i've hyped quite a bit on the TCC business, primarily because i thought it was important to understand the operation and what would happen if it didn't work right. I talked with the tranny guy at work on saturday and came to the conclusion that in the event that the TCC doesn't work out in the end, it's not the end of the world. Since most of the torque converter's life is slipping anyway how much more difference is a few hundred rpm cruising down the freeway going to make? I can say that i honestly don't know; not without further in-depth research anyway.  The primary operation of TCC seems to be during cruise conditions. (how often are you cruising while you're in 4X4?) I'm sorry if i've confused anyone.