3G Tacoma Hard Downshift

Had the truck slam hard when trying to pass a car in the highway--all within legal takeover requirements for the curious folks.

It was a HARD drop/slip. Its been driving okay since, but what is the least invasive way to check to transmission damage?

 

Driving fine since, guessing it's OK. If not it will let you know sooner or later. More interesting is why it did it in the first place? I'd be doing a fluid level check for starters.

 

Update:

Dumped 5qts, swapped out the trans filter, replaced 5.5 qts, heated up to 116 F, pulled the overfill plug and capped it off. Shes shifting a lot smoother now. Its no Lexus, but its WAY smoother on the shifting. Thanks.