Auto Transmission, 1-2 shift after sitting

Hello,

I need some fresh insight into a shift problem with this A340E transm.

After sitting for a while; overnight, every time, or for several hours, sometimes, the trns will not upshift 1-2. After some driving at 30 mph or less and some manipulation of the gas pedal it will up shift and then the problem is gone, it drives and shifts fine. But when it sits overnight or for several hours, I have to go through the same steps, drive slowly, ease off on the gas pedal to make it shift, until it goes through the 1-2 shift one or two times then the problem goes away.

The need for new insight is because I've tried the following repairs, drain and refilled the transpan, AT fluid enhancers, cleaners, seal swellers, new filter, new 1-2 solenoids, new TPS (throtlePositionSensor) and the problem is the same.

Next I disconnected the solenoid connector on the outside of the gear box and shift with the shift lever, the transmission works fine, 1-2-od just like the diagnostic sheet said it should. The sheet then says if it works, ie shifts manually with the plug disconnected then the problem was in the electrical controls. So I start looking there.But, I don't get any DTC codes showing any sensors, TSP, AT Temp, Coolant Temp, Speed sensor(s) 1 or 2 are faulty. No solenoid DTCs, except if I disconnect the Solenoid wiring to make the manual shifting trial. These clear themselves after reconnection and driving. One other instance was a P0770 which shows a lock-up solenoid malfunction, use to get it once in a while but have not seen it for some time.
The throttle cable is adjusted to within specification. But, it seems there are times when the problem is in effect, ie won't shift, I can ease up on the gas pedal and it makes it shift. What I mean is; from a stop and trns in D I depress the gas run it up to 2500rpm or so and let-up on the gas and it will shift, this is a mystery to me but it led me to belive that the TSP was faulty, I was wrong. The new TSP made no difference.

So, if you can, maybe you can send me in the right direction to find an intermittent fault that clears itself after a few miles but re-occurs after sitting for a while.

Thanks for your time.
:)

I noticed mine doing something similar several years ago. That is when I learned that the computer apparently won't allow the tranny to shift until the operating temperature gets to some point. If yours just started doing this, I would guess that the temperature sensor has deteriorated, giving an inaccurate signal. The computer can't detect that kind of failure.

reb,

It could be the problem, I'll have to check it out. But, I'd was under the impression that the temp setting was for the up-shift from 3rd to OD or 4th gear. My trany won't upshift 1-2, until it get warmed up, so you may be right, I'll have to check out the temp probe.

Thanks for the input.
al

I'm not sure which gears are affected. I noticed it about 6-8 years ago. Mine would wind out tight if I tried to get up to freeway speeds before it warmed up.

6-8 years ago, are you still driving it? I hope so that would be encouraging news.

To the best of my knowledge the up-shift function you describe, is one that my truck has demonstrated. however now because I can't get mine to shift from 1-2 until I've driven awhile, the engine temp is up to normal by that time and the 3-(4) OD shift is ok. Again because the temp is up to operation level.

Some time ago, before this problem I have now showed up, the previous owner got a P0770 code and his mechanic changed the #3 SL solenoid. well not long after I had the truck this code came back, I reset it, and ignored it. So for a time, maybe once a month the code would set the MIL light, I'd pull out the code reader, P0770, same as before, reset, and so on. I thought, fix it fix it, but how??? Reasoning that the solenoid was only a few months old it couldn't go bad that quickly, so what else can I do?

I considered many things, disconnect the light, ha! ha!, talk with mechanics, take it to Toyota, but what I did was check the fluid level: Ok, now drain the transmission pan, 3 new quarts of fluid, dextron III and that should do it.

Well guess what, right after that I get the 1-2 shift problem, almost unnoticable initially, early morning, once in a while, but then more and more often, but no P0770 codes anymore. Well in truth, only one time in 4 months, but it won't shift 1-2 until it's gone through several shifts by throttle manipulation or sustained driving at 3 to 4k rpm, then like magic the trans shifts like new until it sits and cools down. And yes the temp is up to normal by then.

ah,the sweet mysteries of life.....
:confused:

I am still driving it, with no problems. I don't know whether it still waits to shift because now I have to drive 20 to 30 miles before I can find a place to get up to freeway speeds. I don't notice anything unusual below 35 or 40 mph.

Sounds like yours might have some sort of minor idiosyncrasy. If you figure it out, let us know.

My truck also has this problem, I have noticed that it takes roughly 1 mile for mine to shift, and its like clockwork, shifting at the same time every time but only after it has been sitting over night or thru the work day. It also happens to be around a mile or so when I notice my heat begins to work, aka my engine has reached a good temp so I am going to agree with the temp sensor idea.

Mine is not quite that regular, in terms of distance I mean, but it does seem to be related to temp. For example I let it sit and warm up, say 10 minutes or so and drove away, the first upshift seem to miss, short run down the drive way to a stop sign, but after that at the next shift point, just like new, smooth solid and at the right time. I just can't figure out why? :confused:

Thanks

Well I took the idea and tried it out, that is I disconnected the wire from the top of the sensor, the check engine light came on right away, the engine started hard and did not idle up as it usually does when first started. But it ran so I took it for a test spin there was no difference in the routine, first few attempts to upshift 1-2, no go. Then, just like before, after the temp gauge moved up to operational temp the shift 1-2 worked fine.
I came back, plugged in the temp sensor, checked the codes, P0115 showed, according to the list, it noticed a temp circuit fault. Cleard the code, restarted and drove it, all is back to normal.

I can't see how this had any effect on the shift situation, it did make starting hard because the engine was cold, sat overnight, and the fail safe mode for this condition, no temp probe, is for the ECM to assume an 80 degree condition. But, maybe I'm missing something?

Al :confused:

I just looked at the factory manual for the transmission. It shows a block diagram of the interconnect of the sensors, ECM and the actuators. The only temp sensor is the A/T fluid temp sensor. I was thinking of the wrong one. The A/T temp sensor is located on the passenger side of the transmission, near the front. Is that the one you disconnected?

Howdy,
No, I took the coolant temp sensor out, top of the engine, near the injectors/intake manifold.
I haven't disconnect the A/T temp sensor thinking it is an overtemp protection, in the event you run up the temp of the transmission fluid with heavy loads or loss of cooling.
The upshift function, from owner,s manual and other sources, is a fuel efficency or driveability issue and it keeps the trans from going into 4th gear until the engine is warmed up, different set point for different vehicles, Tundra, Camary, T100, but again it based on coolant temp.

PS there's also a coolant temp sensor that operates the panel gauge, separate from the one we've located here.

factory manual for the transmission? lots of good info?

I'm thinking it time to go back to the A/T fluid issue. Maybe a complete fluid change, then refill with a synthetic, any comments on Fluids?

I just looked at the factory manual for the transmission. It shows a block diagram of the interconnect of the sensors, ECM and the actuators. The only temp sensor is the A/T fluid temp sensor. I was thinking of the wrong one. The A/T temp sensor is located on the passenger side of the transmission, near the front. Is that the one you disconnected?

Very interesting, I've just read an article explaining how important the A/T fluid temp is.

I'd thought it was only a warning circuit, like a red light goes off if it were to get too high, but the article pointed out that "shift schedules, accumulator pressure and lock ups can be effected by the temp signal". With that bit of info under my cap I'm wondering what you transmission manual says about this sensor? :confused:

I'm using Alldata for info but it only says code P0710 would indicate a failed sensor, no code on the reader, and I can disconnect it and test drive but don't know if that would prove anything.

So here's the question, What does your manual say about, shift schedules etc based on this temp probe?

Thanks in advance,
Al

I can find no info about shift schedules. The manual does not seem to include operating specs.

Closer examination of the manual shows there are apparently two versions of the A340E transmission--one used with the 2JZ-GTE engine (I don't know what vehicle that applies to) and the other used with the 3VZ-E (Truck, 4 Runner, and T100), 2JZ-GE (Supra), and 2TZ-FZE (Previa). The block diagram for the first shows the temp sensor in the loop. The block diagram for the second does not show the temp sensor, so I can't say for sure the T100 transmission control uses the signal. However, all the transmissions have the sensor. I would expect all versions use the temp sensor signal in basically the same way and that it was left out of the second block diagram.

Howdy,
I've had an light come on, literally, on this problem which I think puts the trouble back into the gear box itself. Let me explain. transdude, owner of IPT, www.importperformance.com transimission suggested checking to see if the ECM was calling for the 1-2 shift at the correct time. I've made up a test light circuit for the #1 and #2 solenoids and as I said above the light came on according to shift schedule, I found the info at www.autoshop101.com where there's an good resource, two different text books loaded with operational and diagnostic help on this trans, in fact toyota A/T in general.
So the ECM is telling my gear box to shift, The solenoids are new so I know they're working but it won't up-shift on it's own. Now I can sometimes treadle the gas and make it shift but the lights show it goes into 3rd, not 2nd.
One other point, in the diagnostics I got form alldata the suggested disconneting the solenoids, external plug/connector on the trans case; drive using the shift lever, i.e. start in low, upshift to 2 and so on.... This they said would show if it was the gear box or the ECM. If it shifts manually then the problem is in the electrics. I did this test and followed the path, ie sensors, contacts, pin voltages, temp. probes, all working fine... So what happen? The data at autoshop, shift schedule shows that with no electrics to the 1&2 solenoids the only speeds available are 1, 3, OD, my problem was and is in second gear.

All that said, I'm back to the gear box, thinking it's a sticky 1-2 shift valve that, according to my deductive reasoning, reacts in this way: cool morning, FL never gets below 40, or prolonged sitting, time enough to allow the valve body/ trans in general to reach ambient temp, 40-80 locally, and the valve hangs, or the spring that pushes it up can't overcome the drag, and no second gear; warm up the gear box/ valve body, by driving, and the ECM makes the call, the solenoid opens, the valve now free enough to move and smooth toyota shift. every time...

Now how to unstick or free up that valve?

PS.
Two other things in the history of this trans, 1. the 1-2 shift valve also is in the Lock up circuit, and if I'm right about this, may be the reason for the P0770 code that use to come up now and again, code books says, Solenoid E malfunction, and 2. no more P0770 codes, but this 1-2 shift issue came about right after I, drained my trans pan and added 3 qts. new dextron III, In essence I, " fixed it till it was broke".

check out these sites, good info,

Al
Still looking for a way to make all the folks who said, " put a rebuilt unit in it and the problem will be fixed ", wrong.

Any Ideas? :clap: :clap: :confused:

[Still looking for a way to make all the folks who said, " put a rebuilt unit in it and the problem will be fixed ", wrong.]

Sounds like, from what you say, they might be right. A rebuilt transmission shouldn't have a sticky valve. However, you might prove there is a cheaper way once you get it all figured out.

Keep us posted.

I have a similar problem with mine in addition to it not shifting 1-2. After I drive it 30 miles and then let it sit for five hours when I start it and put it into reverse it slams into reverse and then when I put it into drive it does it in all of the forward gears until I have driven it one half a mile. Any ideas? thanks :)

Hard to say exactly because of all the the things that come to play in how the trans shifts and when it shifts, but one thing is common, the fluid. In my situation I've looked at a lot if not all of the contributors to the shifting function and they all checked ok, and now I've gone back to the fluid. On a suggestion I tried a product called"Lubegard" and I think I've seen some improvement in my 1-2 shift problem. I'm going to wait untill the next oil change, and drain the trans oil pan, add new 3 qts new fluid, dextron III and another Lubegard and drive it, and see what happens.

Guys, I read somewhere that the check balls in the valves become smaller over time and then become disloged causing the transmission to shift harshly. I can not remember where I read this it was either in consumer reports or on the NHTSA web site. If you have narrowed it down to the valves it may be this. Just $.02 I will look around and see if I can find that article.

A good transmission shop agreed to check the valve body, hard to find a shop willing to inspect and determine if a repair was possible, everywhere I'd gone before, wanted to rebuild or replace...

In any event there was debris in the 1-2 shift valve and lock-up valve as well. They cleaned and overhauled the VB and now it shifts like new.

Al Wilson

:clap:

It is good to hear all turned out well. Thanks for the update.

Al,

Thanks for all your persistance in solving this problem. I have the same issue..can you tell us the details of how you fix it yourself since I would like to fix this problem also or did you take it to a shop, if so what did they charge you.

Thanks,
Matt

Hey Matt,

The story did not end with the rebuild of the valve body. The real culprit was the clutch disks that were flaking and spreading particulate matter into the fluid, which cause the problem to return.
The real fix was to have the gear box rebuilt, at about 1,300 dollars or so.
It's been two years or more now and no shifting problems.

Good luck,
Al