Sorry to hear, Dr. Z

Could it be just the torque converter going bad (failing to lock or stay locked) for some reason, instead of the entire transmission?

On my four-speed automatic it does a 'shift' at 45 MPH but maybe it is actually the TC locking up also.

 

But yeah if your transmission is hydraulically controlled then the control of lockup, if not in the TC itself, is hydraulic via some other part of the transmission. At least you can eliminate an electronic cause, I guess.

 

I warmed it up a couple days ago and added some ATF, but the problem persists. I may be slightly over full now.

I believe the lock up is actuated by a governor, so some sort of centrifugal force mechanism based on how fast something is rotating. I was wondering if maybe something is just "gummed up" and not allowing it to function correctly. I'm not sure if that explains the slow shift from 2nd to 3rd though.

And I wonder if there is some sort of friction material like a manual transmission clutch that is worn away. When the problem started it would go in and out of lock now it's more like it never locks, so maybe there is some sort of friction material that wire away then wore away even more.

The repair manual trouble shooting doesn't mention my specific problem.

The cable from the throttle to transmission feels like it has tension and springs back when pulled independent of the throttle, so it doesn't feel broken.

I'm not sure what my next step should be. And I'm not sure if I'm damaging it more driving this way.

Any advice or suggestions are appreciated.

 

When was the last time it had a fluid change? At this point in time, I'd either look for another trans to put in it, or start saving for a trans replacement IF you plan on keeping the car.

 

Sometimes you can blow out blockages. Have you tried to GET ON IT?
Let it run through the gears and do some full throttle shifts if possible.

Slightly overfull shouldn't hurt anything.

 

I'm a little scared to just floor it when it's trying to shift from 2nd to 3rd slowly. I have given it pretty good throttle off the line.

I only drained and refilled the trans a few years ago, so not a complete drain and fill since most of the ATF doesn't drain. I'd try doing a more complete drain and fill before pulling the whole trans.

I have not driven it much the last 2 years since I was out of town a lot and using my other Corolla. Like maybe 20k in 3 years. And only 5k in the last 2 years.

What are the effects of old ATF? Could it thin out enough to drop the pressure and cause these symptoms?

I'm not sure I'd want to replace the trans. And I'd like to know the cause first and if there's anything I can check without pulling the trans like just dropping the pan.

 

Old trans fluid breaks down and gets dirty just like old oil..
Long list of affects from breakdown and particule contamination

 

It might have absorbed some water from not being used as well. A fluid change wouldn't hurt, and neither would replacing the filter.

 

I have the 1990 Toyota Repair Manual. The troubling shooting section doesn't say anything about my specific symptoms. The closest things related to shifting problems was low fluid pressure. That's why I was wondering if a clogged filter could cause that. I'll have to look through again. The transmission chapter is very long.

 

Yes it can cause that

 

Dr Z, not sure if it will help, but on a '93 Pontiac Sunbird there is a TCC (Torque Converter Clutch) Solenoid, apparently, that controls the TC lock / unlock. Over on Cartalk they were saying that you can (at least on the Pontiac's automatic tranny) disconnect a wire to that solenoid which stops the lockup function but also may help stop your Corolla's frequent locking / unlocking, maybe? I realize the Pontiac's tranny design may not be super similar, but just in case it helps. But also, if there is a similar solenoid in the Corolla's Aisin transmissions, maybe it could be cleaned out or replaced?

https://community.cartalk.com/t/what-happens-if-i-remove-the-wire-to-the-tcc-solenoid/45727

 

The A131L is all mechanical. Nothing electronic controlling the lock up.

 

Since it's all mechanical, I'd have to go with a converter getting ready to go out. I don't know why it would, but that's about the only thing I can think of. Unless you're driving in a lot of 50 mph traffic, and not actually getting up to 50 (where it would be in lock up). I say that because my A131L in my 92 Geo Prizm goes into lock up @48 mph. RPM doesn't seem to make a difference either, as it's speed controlled. Unless there's something in there that might be affecting when that would happen.

 

Oh okay, so no solenoids on a hydraulically-controlled transmission. Shows you how much I know. XD Thanks for the info.

 

I thought about your tires size, but whatever is showing on the speedometer should correlate to the RPMs. I mean if you put smaller tires on, then when your speedometer reads 45mph you are actually going slower, but your RPMs would be the same as with bigger tires. Like if 2500rpm is 45mph with the torque converter locked up then the tire size is irrelevant. The engine and transmission don't know how big the tires actually are or how fast you're actually going down the road.

Now, if you ever removed the needle from the speedometer and put it back, then it could be off.

 

I've never even had the plastic (glass(?)) off it. I'm wondering if maybe there's a mechanical sensor that engages the overdrive, that might be driven off the speedo cable assembly inside the trans. I've never really looked, as I haven't had a reason to go digging into the trans.
However, the slightly smaller tires do raise the engine speed very slightly, so the torque converter would also be raised when trying to engage the lock up (in theory it would lock up sooner, but it doesn't). It seems to know when you've reached that speed for it to go into lock up though.

 

I think I may know why there is a difference between ours when I was looking through my repair manual. There were 2 different differential gear ratios for the A131L with slightly different torque converter lock-up speeds.

Gear Ratio 3.526, Lock-up ON 44-50mph. Lock-up OFF 41-47mph
Gear Ratio 3.722, Lock-up ON 42-47mph. Lock-up OFF 39-44mph

I looks like I have the 2nd ratio while you (Corolla Clone) have the 1st ratio.

The 2nd ratio says "OPT of U.S.A". I'm not sure if this means not in Canada, or if it means built in USA, or if it means optional anywhere in North America. My car was built in Japan (VIN JT2).

My VIN label on the driver's door frame shows
A/TM:-552/A131L

The first part -552 is the differential code. I'm guessing your is different.

I haven't found any websites that decipher this particular code, but this place shows what the digits might correspond to or how you use them.

Toyota Differential Identification: Off-Road.com

 

I think I may know why there is a difference between ours when I was looking through my repair manual. There were 2 different differential gear ratios for the A131L with slightly different torque converter lock-up speeds.

Gear Ratio 3.526, Lock-up ON 44-50mph. Lock-up OFF 41-47mph
Gear Ratio 3.722, Lock-up ON 42-47mph. Lock-up OFF 39-44mph

I looks like I have the 2nd ratio while you (Corolla Clone) have the 1st ratio.

The 2nd ratio says "OPT of U.S.A". I'm not sure if this means not in Canada, or if it means built in USA, or if it means optional anywhere in North America. My car was built in Japan (VIN JT2).

My VIN label on the driver's door frame shows
A/TM:-552/A131L

The first part -552 is the differential code. I'm guessing your is different.

I haven't found any websites that decipher this particular code, but this place shows what the digits might correspond to or how you use them.

Toyota Differential Identification: Off-Road.com

I'll have to look and see what's there. It wouldn't surprise me though if you're correct about the 2 gear choices, as my car was built in California at the Nummi plant. It's a mix of GM and Toyota. At least the important parts (engine, trans, brakes) are Toyota parts.

 

The 3.722 ratio was for all Corollas destined for the USA for better torque.

My A131L will lock up at around 49 MPH on the speedometer and stay locked until I drop below that speed. I drive on the highway every day.

I’d say the primary issue is the late shift from 2nd to 3rd at the moment. I would not floor it for the time being.

What color is the fluid? Is it up to the top of the hot region after shifting through all the gears? Has the filter ever been changed? How many miles on the transmission?

 

What color is the fluid? Is it up to the top of the hot region after shifting through all the gears? Has the filter ever been changed? How many miles on the transmission?

Transmission is original, 230k+ miles. I've only ever drained a refilled the ATF once, and that only drains part of it. I've drained and refilled the separate differential. Maybe I'm confused and never even drained the transmission. I'm certain I've drained it on my 97, so maybe I'm confusing them. In any case, I'm sure the ATF is OLD!

The level is at the high hot mark or higher when warm after shifting through all the gears.

 

I suggest changing fluid and filter by drain and refill and seeing if there is improvement. The transmission is probably fine but the fluid isn't making its way through the valve body and filter as easily as usual. I would drive it easy if you have to drive it at all until you do this or you may damage the clutch packs with low fluid.

My friend's 2003 Acura TL did the same late shifting with the notorious 5-speed transmission in those things, and the problem was that fluid wasn't circulating as it was supposed to. The official explanation was this.

as the third clutch pack wore, particles blocked off oil passages and prevented the transmission from shifting or holding gears normally.

His transmission died soon after since the condition is not repairable.

I read an article years ago that made a point about how of all the parts in an automatic transmission, the lock up converter itself is one of the components that fails extremely rarely, and it's almost always something else causing problems. I'll see if I can find it.

I have 292k on my A131L, and I change the fluid and filter every 30k miles.

 

Since you (clearly) don't want to put in a different transmission, or, open it up, only thing left, before turning to the pros, is new ATF and filter. When you did a drain & fill a year or three ago, you only changed the fluid in the pan, while most of the fluid remained in the torque converter.

This time you want to get all the old fluid out, &, change the filter.
If you flush the transmission, you'll refresh the fluid in the torque converter. Here's a video on flushing he trans via transmission cooler in the radiator: LINK
I'd drop the pan and change the filter after the flush, since then the new filter will only be working on fresh ATF. Yes, in that sequence, might be wasteful of ATF, but they tell us not to be penny-wise, and pound foolish.

 

I finally got around to draining the ATF and dropping the pan. I ordered the new pan gasket, drain plug gasket and strainer from Toyota and got them a couple days ago. I didn't watch the video link in the previous post until today, so I didn't do the flush first before dropping the pan. I can still do that if the partially new ATF doesn't improve my symptoms or if it only helps a little. Dropping the pan I got about 3.5 quarts out.

I didn't and don't feel like taking the valve body off and the other few parts that can be removed without removing the transmission from the car. I figure my problem of the torque converter not locking up is probably not related to any of these parts, although I'm not 100% sure about that.

The magnets had a good bit of particles stuck to them. I don't know if it's a lot for a 230k mile transmission that's never had the pan dropped. I'm guessing it never had it dropped in the first 138k miles before I owned it. The hairs of particles on the magnets were not solid pieces of metal, but were more like a paste with consistency of grease, but a little less solid. It wiped off really easy and absorbed into a paper towel like a liquid.

I'm not sure really what else I can do except put the new strainer on and pan and refill and see what happens.

Parts:
Transmission Case & Oil Pan (ATM):
35168-32010 Gasket, Automatic Transaxle Oil Pan, $12.46
90430-18008 Gasket, Drain Plug (ATM), $1.36, (Replaced by: 90430-A0003)

Valve Body & Oil Strainer (ATM):
35330-20012 Strainer Assy, Valve Body Oil (includes 35339-32010 Gasket, Oil Strainer), $29.42
35339-32010 Gasket, Oil Strainer, $4.91 (did not need this because strainer comes with a gasket)

 

Looks pretty clean to me.

 

There was a thin layer of silt-like material on the bottom of the pan that wiped away easily. You can also see it on the strainer. I'm not sure if this is from the friction materials in the transmission or the old ATF or if this is just normal for old ATF in an old transmission. The screen in the strainer didn't look clogged with any large particles.

 

That pan looks like it had a lot of miles without a filter change. I have rebuilt a couple 3spd autos but i have only taken apart an a131L because they have been easier to source used here for $110. I do not know how much metal is normal over time for these, but that looks like something broke to me. I also want to add my tc will lock until over 100mph when i let off the throttle but unlocks around 50 under normal load. I think i have another a131l torque converter lying around if it didnt get wet.

 

but that looks like something broke to me.

Well, I don't have any grinding or weird sounds, so I'm not sure what would have broke. This seems to be just very fine wear over time.

I'm not sure if the lock up torque converter is like a clutch plate and it can eventually wear out or if the ATF was just so old it lost viscosity and that wasn't providing enough force somewhere to trigger the lock up. I'm going to try to flush it like in the video posted above and hope for the best. If it still doesn't lock up then I'll reevaluate my options.

 

So there is no improvement of symptoms with new fluid?

 

I didn't fill it up yet. Just put the pan and strainer back on yesterday. 110°F during the day and 95°F at midnight, so I'm only doing a little work at a time. I only have one gallon of ATF, so I'm going to pick up another gallon of ATF and flush it out the cooler hose like in the video.

 

I haven't taken it out of the garage to test drive it yet, but I did flush and refill it. It's too hot out and I can drive my other car, so I'm not in a rush.

I used Valvoline MaxLife ATF. I added about 3+ quarts then flushed another gallon like in the video about 1 quart at a time. I removed the shorter cooler hose from the radiator on the driver's side then attached a hose from the radiator down into a container. I wasn't sure if this was correct so I put the hose from the transmission into another container, but that wasn't necessary. It turns out the ATF gets pumped out of the transmission down the longer hose to the cooler then comes back from the driver's side connection, so I had it correct.

It takes about 10-15 seconds to pump one quart out. It's long enough to start the engine by reaching through the window and walking up to the front to check the progress before walking back to turn it off. Then I'd refill about one quart and repeat.

I couldn't find the capacity in the repair manual, but it is listed in the owner's manual.

3-speed transmission
Drain and refill: up to 2.6 quarts
Dry fill: 5.8 quarts

The 3-speed has separate differential
Capacity: 1.5 quarts.

So with the original draining and pan removal plus the flushing I went through almost 2 gallons, so I'm pretty sure most of the ATF is fresh now, but I forgot to put the shifter through the gears while flushing, so maybe I left some old ATF in there somewhere in the valve body.

I didn't have a great view of how clean the ATF was coming out during the final one quart flush because my container wasn't clear enough, but the drips coming out of the hose after I shut the engine off looked like clean red ATF.

I'll post after I test drive it and check the fluid level. I'm 50/50 on whether this will solve the problem. I'm a little nervous to test drive it and find out it may not have helped.

 

Thanks for the update.

 

I took it for a test drive and it still doesn't lock up. I checked and filled the level after driving it for a little while and it still didn't work. I tried accelerating hard a few times to try to maybe loosen up any gunk. I noticed if I let off the gas or just barely give it gas it will fluctuate between locking up and unlocking.

What I don't know is if the lock-up part is like a clutch material and maybe it's worn out and slipping, or is there some sort of hydraulic pressure that is supposed to activate it and it's not doing that for some reason. If anyone doesn't know, I guess I'll have to try to figure it out, and if there's any relatively easy way to fix it (like without removing the transmission).

If driving it like it is isn't going to damage the transmission any more, then I could just drive it locally (under 45 MPH) for now.

 

Do you have the FSM? I can check if my '95 manual says anything for troubleshooting. I believe lockup is triggered hydraulically through the valve body on these transmissions.

 

Yes, I have the repair manual and it's more detailed than the 7th gen repair manual. The 7th gen has a separate repair manual for disassembling the transmissions, but the 6th gen goes into all the details.

Your comment makes me think I should have taken the time to remove the valve body and clean and check for any problems while I had the pan off. It was a gamble, but I can always take the pan off again. I just don't feel like doing it right now in the summer. Also, I'd like to know what I'm looking for and/or understand how it works better before doing it. The repair manual mentioned a little about the lock-up torque converter, but I'll have to reread it again.

 

Could there be a brake switch sensor that disengages the lockup if it thinks the brake pedal is depressed?

My understanding is that if there was actual damage to the lock up mechanism your shifts would be harsher and there would be overall problems with transmission operation.

Does the transmission still shift late with new fluid?