The 2004 Highlander with a 3.3L engine and 187,000 miles had a P0500 Vehicle Sensor "A" error. The transmission speed sensor was replaced with an AISIN RST-008-1, which is OE but not OEM. Now it shifts hard between 1st and 2nd gears while the rest of them are smooth. The battery was disconnected for another project; is it still learning shift points improving, is it something else?
Has the transmission been serviced regularly over the last 21 years? At that mileage the fluid and filter (if applicable) should have been changed at least 3 times.
@chucktobias Yes, drained and was filled 6 months ago.
What about the 20 years prior?
Had 150,000 miles when I bought it 5 years ago, before that no records.
What did the fluid look like when it was changed at 150K miles? (Assuming you're the one who did it.) Hopefully it's just a relearning issue but it's possible there's some internal wear rearing its head.
which is OE but not OEM.
The manufacturer of the OE part is the same as the manufacturer of the OEM part. It's the same.
Was it shifting like this before the wheel sensor was changed. Was the battery disconnecting before/while the sensor was replaced?was replaced with an AISIN RST-008-1, which is OE but not OEM. Now it shifts hard between 1st and 2nd gears
If the hard shifts started right after the work was done, the battery had been disconnected, ECU's likely relearning.
@hixster Was running fiine, in fact the upper gears are shifting smother now.
@rlively99 The ECU, wheel sensor/ TCM need time to adapt . Takes a couple of days usually, depending on your driving habits
@hixster Considering the limited mileage I drive nowadays, it will be more than a couple. I hope it is just a matter of learning and not transmission. Changing the transmission in the parking lot at the age of 62 would not be enjoyable in the Texas heat.