2009 rough downshift from 2nd to 1st

In July, I changed my transmission fluid, all 12 quarts, using Toyota ATF. Shortly after, my truck began to occasionally and intermittently do a really rough downshift as I slowed to a stop at a traffic light. It almost feels like I am getting hit in the rear, except no one is there. I can’t replicate it, it is very intermittent. I have a scanner, but it shows no codes or errors. What is it?

 

How did the old ATF look? Pretty clean or black?

 

Did you ever have the trans reflash done to help resolve that as its the idle stepping up when AC is on when you stop. Even after that I still get the bump once in a while on really hot days with AC on higher setting. I need to look at the IAC valve and see if it needs cleaning but probably sealed unit - anyone looked at this before?

 

Are you sure it's not the driveshaft slip joint and not the transmission itself?

 

sounds like the dreaded SLT solenoid problem .

Another member here is having a very similar issue
Give it a look and follow the same instructions . Post back what you find


https://www.tacomaworld.com/threads/shifting-transmission-problems.633187/#post-21747749

 

My 2009 rough downshift was literally not enough ATF consequential to a small leak I hadn’t noticed at the output shaft.

My recommendation is to revisit the level of fluid before moving on.

 

Thanks for all of the reply’s, in order:
The old fluid was pretty clean.
I have had no reflashes, but the AC was off, anyway.
Drive shaft and slip yoke are okay.
No ATF leak of any kind, large or small, but I will revisit the fluid level, anyway.
I am now reading and studying about the SLT solenoid.

 

Are you sure it's not just axle wrap unloading? If you have a GoPro or similar maybe try mounting it underneath so you can see your leaf springs, driveshaft and rear diff. Watch to see if when you stop and feel the jolt, if you see the differential tilt back downwards while the leaf springs unload.

 

I replaced the SLT solenoid, new strainer, Lubeguard platinum, WS fluid, all OEM parts, so far, truck shifts better. Time will tell.