New TSB for Highlander and Sienna transmission from Toyota.
John Goreham's picture

New Tech Service Bulletin Fixes 2017 Highlander and Sienna Transmission Problems

Due in part to a media group's testing, Toyota has a new TSB for Highlander and Sienna.

The newest generation of transmissions from Toyota have given consumers fits. However, the problem is simply the software settings Toyota chose. During a recent test by Consumer Reports (CR), the testers complained to Toyota and the company has now taken action.

Toyota Transmission Problems
The issues are simply drivability. CR reported, "The transmission made the engine rev before upshifting, especially from second to third gear, even under light acceleration. This delayed shifting increased engine noise and made driving rather unpleasant." This sounds very much like the problems that Tacoma owners suffered through before a technical service bulletin (TSB) addresses that issue.

Toyota Fuel Economy
Toyota is making these odd software settings in order to maximize fuel economy. However, it comes at the cost of driving enjoyment. The fuel economy did go up as a result of Toyota's weird settings. No word on if the TSB removes that advantage.

Toyota Transmission TSB and Fix
The correction can be done at any Toyota dealer in about 45 minutes according to CR. The TBS numbers are TSB-0194-17 for the Highlander and TSB-0197-17 for the Sienna

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The 2017 Highlander 8 speed transmission has far more severe issues than simply “software settings”. People have been reporting Toyota denies this softaremupdate TSB even exists. Our transmission failed at 8,253 Miles while my wife was at a stop light. The vehicle was hauled to local Toyota dealer on a flatbed & sat at the dealership for 52 days. We were told by dealer that a "new" transmission was back-ordered from California. After picking up the vehicle I noticed the work order stated part number 30510-48600-84 "REMAN ATM" and "CORE RETURN". The day after picking it up I drove the vehicle and excessive power train noise was present. Vehicle went back the the shop & they replaced both front wheel bearings at 8,392 miles and it sat in the shop another 3 days. Toyota corporate has been less than helpful & we're currently going through the lemon law process. 2017 XLE 4dr SUV AWD (3.5L 6cyl 8AT 8 spd transmission)
I agree that this is NOT just a software problem. My transmission failed after 15,000 miles too. I was told it would take a week to fix, but after reading many horror stories of backordered transmissions I am wondering if that's true.
I just purchased a clean used 2017 Highlander / front wheel drive / 35,000 miles one owner manufacture DATE 3/17 and it shifts fine....I disabled the start - stop feature & drive it easy & sensibly.....most transmission problems stem from operatr error.....too many stupid drivers