Automatic transmission shift issues

1998 prerunner V6 2WD Auto
For about the last year my 4speed auto was slow to shift from 2nd to 3rd until the engine heated up. It generally took about a half mile of driving at 25mph. Following that it would shift normally for the rest of the day. I started having other problems with the trans and opted to have it replaced with a Toyota remanufactured trans. All work was done by a Toyota dealer. The newly installed trans is doing to same thing, leading me to believe the shifting problem isn't in the transmission but is coming from some bad sensor data being supplied to the computer. My question is, what components supply data to the computer that might result in the delay in shifting from 2nd to 3rd?

 

@gearcruncher might know something

 

Is there a cable from your throttle body going down to your transmission ?

Are you sure the transmission is taking too long between second and 3rd gear ?


Its normal for the transmission to have to warm up before shifting from 3rd to 4th . The computer in your truck prevents upshifting to 4th gear until your engine warms the transmission up to proper operating temp .

Have you scanned for codes ?

Go here and identify your transmission . From there , we can assist you with a more in depth diagnosis
https://www.atsg.us/atsg/transtype

 

My transmission is the A340E I have had this truck for 16 years and don't recall the shifting issue until about a year ago. The newly installed remanufactured transmission is exhibiting the same issue. I don't have a check engine light which tells me that the computer isn't detecting an issue. Can there be a code without the CE light? I hope what is going on is normal and I just haven't noticed it before.

 

I have had 3 different automatics over the last 10 years. Drove manuals before that. Every single one has done what you are talking about on the first drive off in the mornings. about a mile maybe 2 depending on the outside temp and all is good for the rest of the day.

 

OK you have the E model .
Yes , there could be codes without the check engine light illuminated .
It was mandatory back in 98 to turn on the check engine light if you were polluting the air . All other codes were basically hidden until you scanned for codes .
With this being said , there could be all kinds of codes causing your issue . Considering your transmission is the computer controlled electronic model ,scanning for codes is the next step in diagnosing your issue .

https://www.tacomaworld.com/threads...sions-write-up-your-4-speed-automatic.325531/

 

There is normal cold operation with delayed shifts .
I believe your owners manual talks about it being normal for delayed shifting during warm up .

Then there is abnormal delayed shifting during warm up like a throttle position sensor that doesnt work correctly when the engine is cold and then functions fine once the engine warms up .

Considering the OP is bringing this up and posting about it , its obvious he thinks there is something different about the way the transmission is warming up now in comparison to the way the transmission warmed up before

I am wondering if Its possible the OP may have a glitch with some of the computer controls ?

 

Could this not be as simple as your coolant not being at 130 degrees or above before it starts to shift normally? My V6 prerunner doesn’t shift into 3rd until the coolant has warmed up to 130 or above. I suspected this before I installed my scangauge years ago, but confirmed it after I installed the gauge. As soon as my coolant/water temp is at 130 or above it shifts very smoothly.

 

Sounds like your trans is doing pretty much what it's designed to do. You can do nearly as much damage to a trans with cold fluid than you can with fluid that's too hot.

 

Thanks for the replies. Perhaps I am making a mountain out of a mole hill. I’ll keep my eye on it.

 

I think your problem was real. I have a 2001, same tranny, A340E, shifting hard between 2nd and 3rd and slipping in 4/5/6. It stays in a lower gear and howls loud when it’s working on the freeway. It also jolts violently shifting into D/R, on startup and usually even when the tranny is warm. The rpm at idle tends to be 1100-1200, and this is when it always jolts. When I’m lucky it idles in 800-850, and rarely jolts, if so, much less significantly. I performed the forbidden tranny flush and filter change, noticing that the fluid was red but not totally transparent, and there were a few small metal shavings/shards on the magnets in addition to the normal particulates, probably from the violent jerking shifting into gear. It made the fluid more viscous and the problem slightly worse, but I added 1 1/2 bottles of Lucas tranny fix and it’s running much more smoothly for now. I’m thinking it could be the clutch packs that were damaged, but I don’t think that’s the root of the problem because it jerked violently before metal shards started showing up in the pan. My hypotheses on the root of the problem are in the shift solenoids or internals of the torque converter. In any case, both are probably in need of replacing at this point, so I’ve found a salvage A340E I’m having installed, and will read up on the solenoids to ensure those are functioning. I don’t want to replace a transmission just to have an electrical problem destroy it like what likely happened to the last one. Any opinions?

 

I've got the opposite problem, my transmission shifts 2nd to 3rd super early, no diff whether cold or hot.

 

my truck would shift somewhat hard before it warmed up good. but after I had the transmission flushed with new fluid, it doesn't do it any more. From what I've seen and read up on, there are 3 solenoids in the transmission, just above the filter/screen. you might want to replace those before installing the salvage yard transmission. just a thought.

 

At this point I’m inclined to think there’s already been damage to the torque converter, whether or not it stemmed from solenoid issues. If I replace the transmission I imagine it would come with its own solenoids, so I think my decision is between a new converter + solenoids if that’s the issue, or tranny swap. Regardless, I want to ensure the issue is not an electronic/computer problem so that my repairs last

 

Normal A340 transmission operation is a delay in 2-3 shift when cold. All 3 of them in my family do it. 2 shift hard. One not as hard. The one not shifting hard has 300k on it. The other 2 are under 200k. Slipping would be the clear sign of issues. These transmissions were not the fancy adaptive units later models got, so they’re clunky because they’re still very much a mechanical setup with electronic control.


They will also whine in 1st gear. Well the 2wd does. The 4x4s do not

 

Have you checked the slip joint and greased it recently? The jolting is a sign it’s not greased properly.

as for the other issues that may be internal transmission problems

 

That’s a relief to hear. I’ll check the slip joints. What about the metal shards in the pan?

 

Slip joint, do you sometimes get the “getting rear ended” feeling at a stop too?

 

I just bought it in decent condition with 300k. Inspected the engine when I did the VCG replacement, and it looked like new. The previous guy had the radiator/cooling system and suspension replaced with OEM parts, and I replaced the rear end. I’m hoping all it needs at this point is slip joint greasing and maybe tires…

 

I mainly was concerned bc this rough shifting never happened until recently. Jolt has been ongoing