Quick background…I had transmission shudder, so I recently dropped transmission fluid pan, changed gasket, filter, & did 3 drain & fills using all OEM Toyota products.

My driving style is is super chill. I’m a feather foot when accelerating this boat, & try to maximize MPG.

The past few days, (I believe I’m in 3rd or 4th gear) while driving around 40 mph, the transmission suddenly disengages. I can floor the gas pedal, & it feels like I’m in neutral, the tachometer doesn’t respond when I press gas pedal, and mph stays around 40 mph. After about 10 seconds, it suddenly re engages, like nothing happened. There’s no jerking or anything out of the ordinary when it disengages, and when it reengages, once again, it slips into gear like butter. I don’t feel or hear anything.

So far, it’s only happened once a day for the past 3 days.

I reset the ECU by disconnecting my battery thinking this was the problem, but it happened again tonight.

Do I need a ECU update to correct this?

EDIT: after digging deeper, it seems like my transmission is slipping. My Indy claimed the fluid was at correct level, but how am I to confirm this w/o a dipstick? Will techstream give me a accurate figure?

Would a bottle of Lucas transmission fix fix the slipping, as it claims it does?

 

You need to make sure the level is correct, the trans slipping will flare RPM to redline so if the tach doesn't respond that is not the problem. Make sure the tech didn't damage any connectors, plugs, etc near the pan, you also need to command a full trans relearn when you change the fluid so the trans offsets are all reset and learned for new fluid vs the old. The fact you aren't losing speed and RPMs are not flaring implies to me you are looking at a control side issue

 

Do I need to use Techstream to reset?

 

Yes or some other dealer level tool/software, I have an Autel ultra and elite2 that can both do it

 

Sorry to read you still have the problem, so is the rpm not changing or is it still the same problem?

I know when I did mine it took awhile to get the car level on ramps because all garage floors if properly built have a grade, once that car is on the hoist nobody is going to get a level out to check.
If your trans is slipping the relearn wont do a thing for you.

 

yes, rpm stays the same, even when I keep pressing gas pedal.

When the gear reengage, it’s like nothing happened…shifts like normal

 

Good point Gerf. The issue of leveling is crucial as well as temperature when checking for proper fill level. It pays to hire a shop that knows Toyota products. The OP mentions an indy shop, which is fine, but no mention of Toyo expertise. If they are qualified, I would trust that the fluid change was done correctly. Even then, gunk can be released into the system, like a blood clot in a person. Since the shop has diagnosed slipping, what do they suggest? Avoid any liquid "fix it" products with this trans. It's been mentioned many times on the forum that the trans is very reliable and long life, making for an abundance of quality used units if necessary.

 

If it was my car, the next time it happened I would stay calm and keep my foot on the throttle and at the same time shift to neutral to see if the rpms instantly jump. Sounds funny tho as was mentioned if the rpms don't go up it's not slipping, like some kinda prohibit is going on.

 

taking it back in RN. He said he waited till fluid was at 46C & filled till it started dripping out of overflow plug.

i went to N back to D & even manual mode. Engine revs, but tach stays around 2,000.

in hindsight, moving forward I’m taking to Lexus or Toyota expert for future jobs like this

 

That is wrong, he should've put in what he took out plus a half quart or so...brought it up to temp and then set the level by way of the overflow fairly quickly, you can't ball park it and add more room temp fluid till it starts to drip.

Still, with the tach somewhat freezing like you describe with no climbing revs when you put it in neutral it's hard to imagine that being a trans problem.

 

My apologies, let me clarify...

Mechanic put in the same amount of new fluid, based on what came out. He then added more fluid in until it started to drip out of the overflow.

I confirmed w/ him this morning that his alignment rack is perfectly level.

Car is sitting in the parking lot waiting for the fluid to cool down to proper temp before he adds in more fluid.

We went on a test drive together & of course, tranny was shifting smooth.

If it's not a transmission problem, what could be the culprit??

TIA

 

I have no idea, don't like to guess much but the rpm thing to me as described doesn't point to the trans. Has there ever been any codes?

Diagnosing over the internet is only consistent with simpler problems but I have a background in the trade and have one of these so I'm not a total moron.

 

Thanks for sharing the photo. Something to be proud of.

 

LOL...My next question to you was your background, because I knew you would at least have a solid mechanical background, but now we all know!

No codes. I ordered the knock off Techstream, which I'll get tomorrow. At this point, w/ all the $$$ I've paid the past several months, I figured it'll come in handy!

Off topic, but how does your sub hit now that you dialed in the LC2i?

 

Well, it's better than a poke in the eye with a sharp stick.