Over the past few years, owners of Toyota Highlander and Sienna minivans with the direct shift 8AT transmissions have experienced many problems. This involves the eight-speed transmission known as UA80, UA80E, and US80F. As a result, a class-action lawsuit has been filed in California. It covers over 1 million Toyota 8-speed transmissions. 

The issue has been owners of either 2017 and up Highlanders and 2017 and up Sienna minivans experience harsh or delayed shifting, delayed acceleration, hesitation, jerking, unintended acceleration, lurching, and excessive RPMs before upshift occurs. The plaintiffs claim Toyota actively concealed 8AT automatic transmission defects according to CarComplaints.

The dealership said the Toyota Highlander was performing normally

Florida plaintiffs purchased a new 2018 Highlander XL. Within the first few hundred miles, they experienced “hesitation and surging while driving at low speeds, in stop-and-go traffic, and as they accelerated to join the traffic flow.” When they took the Highlander into the dealership they were told the vehicle was performing normally. 

At 2,000 miles, 8,730 miles, and another time the Highlander was returned to the dealership. Each time the owners were told the car was performing normally. After the last return to the dealership, a senior technical service advisor allegedly said the eight-speed transmission problems “were common to Highlanders and other Toyota models and were well known to Toyota and its dealers.”

A Toyota technician “found it to perform like a known good vehicle”

At 11,930 miles it was returned yet again. The dealer didn’t inspect the Highlander but informed the owner that a “Toyota District 2 Fixed Operations Manager” did. He reported that he “found it to perform like a known good vehicle” and did “not exhibit any warrantable concern.”

He continued, “Today’s vehicles . . . are driven by wire which means they do not have a throttle cable so they may exhibit very slight lag due to the ECM processing. The current eight speeds transmissions are geared to keep the engine in an optimum operating condition which may not meet the customer’s desired performance but in every case, a little extra pressure on the gas pedal improves responsiveness, and customer satisfaction can usually be obtained.”

In October 2019 the owners took the Highlander to a different dealership. The technician there said the transmission problems were caused by an internal failure on the transaxle assembly. They “replaced the transaxle assembly and associated parts per bulletin T-SB-0160-18.”

Since that transaxle replacement, the owners say the Highlander performs worse

Since that transaxle replacement, the owners say the Highlander performs worse than before. In another bulletin, Toyota said some 2017 Sienna minivans can experience a lack of power. Additionally, high RPM at shift points 2-3 shift, hesitation in lower gears, and stays in gear too long before shifting. 

Two more bulletins were issued before Toyota technicians were advised to replace the transmissions with remanufactured transmissions. The lawsuit alleges that the 8AT transmission makes driving vehicles it is installed into dangerous and hazardous to passengers. It also says surrounding property is in danger from the transmission hesitation, jerking, lurching, and acceleration issues.