ATF Change and 4rth to 5th gear change Issue

Hey all,

I changed the ATF (full flush) about 5,000miles ago in my 2015 Tacoma TRD Off-road when it had about 55,000 miles on it. The fluid was certainly brown and had a slight burning smell to it but not nearly bad enough to call the fluid destroyed.

I changed my tires from the stock tires to BFD All Terrains load range E (So they are heavier) 265/75/16. The tires are a little larger and weigh more. This happened around the exact same time i changed the ATF.

My issue is that when going up a hill the truck will downshift into 4rth gear and when coming to the top of the hill the truck will seemingly stay in 4rth too long. I'll give it 15-30 seconds and if it doesn't switch into 5th within that, i'll move the shifter over to 4rth and back to 5th and it shifts perfectly fine into 5th.

I have checked the fluid level multiple times when it is in the correct temperature range and I get a very slight trickle when in the correct temp range. Fluid level seems to be OK.

My questions is am I imagining things happening now that didn't before? Should the transmission have been 'reset' somehow to accommodate the new fluid after the full flush? Has anybody else experienced this?

Thank you!

 

I think it's normal. Toyota programmed it like that to make sure you're actually done climbing the hill before it goes back into 5th.

Try romping on the gas on flat ground, like you're passing someone... I bet it doesn't do it then.

 

Try disconnecting the neg terminal for 30min or so.

You are certain the level is corect?
How much fluid was used?
was it WS fluid?

 

Yes, i'm certain the level was correct. I can check again. The level was checked when the temp was in range and i filled tranny with engine running until a small stream came out.

I dont remember exactly how much fluid was used as it was a while ago but the fluid level was checked and in spec.

WS approved fluid was used -- valvoline maxlife has been suggested to be a much better fluid than Toyota WS so i used that.

I did disconnect the battery terminal but to no avail -- same issue. It could be normal but it doesn't seem right.

 

Just remember, when the truck is off, the reservoir fills and in turn fills the overflow tube. So, to actually get it correct, you must over fill the trans, maybe a half quart, to get an accurate level. Just add about a half quart when cold, do the temp check thing, then pull the over flow. You should see alot more come out. When ever the truck is ready, I like to put the heater on full blast to keep the temp in range longer. At least it seems like it does. Gives you the feeling that you don't have to rush. I don't think brown burned up trans fluid is good though. That is usually an indication of a problem, especially only at 50k miles. Maybe our resident gear specialist has more insight, bit I would say that maybe some clutch packs got toasted, or maybe trans was on the verge of over heating a time or two. Hey @gearcruncher , what you think here?

 

Thanks I appreciate it!

I'm a little confused then. I was under the impression that fluid can be checked with the engine running and filled with the engine running. If you check when the engine is OFF then a ton of fluid will fall out like you said and then the tranny will be light on fluid, no?

If the engine is at the correct temp or between the range, then fluid can be filled until it starts to stream out of the transmission, no? A little stream coming out would indicate that you're at the correct level?

Did I do something wrong?

 

Yes, check when running. I meant when the truck is off, it fills that overflow, and when you run the truck and pull the overflow, it can give you a false indication of being full. I would add fluid before the check just so it warms up the same as the rest rather than while the truck is running and you're adding cold fluid. I don't know how much that matters in this situation, but in my head, makes more sense.

 

its normal for it to hang in gear like that. Its how these trans work and is only perpetuated by the fact you have MUUUUCH heavier tires that are also bigger.

 

Ok awesome. I thought that could certainly add to it as the truck struggled more after I put the tires on. Thanks for the confirmation. I'll be changing out the oil every 30k. It was pretty simple and fairly cheap, so why not keep the tranny in great shape?

 

I agree it is normal for it to hang in gear.. My 2014 does the same thing going up hills.. 27k on it and I haven't changed the trans fluid in it yet

 

So my issue isn't with it hanging in gear going UP a hill, it's when the hill is over with, it probably takes it 1/4 miles or 1/5 mile (15 seconds) before switching into 5th. Really odd that it stays that long after being over the hill

 

Its the tires.

Prove it by borrowing a set of stockers from a friend and go up the same hill.

While that might sound like a like of work, if the friend needs a tire rotation and you have 4 jackstands between you........

Not to mention its free.

 

My Tacoma and my Tundra both do it, and they both have the same A750 transmission, it's just how they are programmed.

 

on the gas, or off the gas?

, it may be trying to engine brake.

 

https://www.tacomaworld.com/threads...th-pics-for-second-gen-4-liter-trucks.289913/

 

If I completely let off the gas it still stays in 5th. It's only when I wait for a period of time, or if I shift to 4rth then immediately to 5th it will shift into 5th gear.

 

That's a good idea thanks. If it continues I'll see who has a set here in Austin

 

Where you at in the ATX?

 

North loop. 54rth street

 

Also if I Press the gas pedal on flat ground or decline, the car will downshift to fourth in immediately ship back to fifth gear once I let go of the gas pedal or slightly back off. It only does this or messes up when I'm going uphill on the incline and find as I come over the hill it stays in the gear.