My 1999 LS400 with 120k miles is shifting too hard. At first it was just from 2nd to 3rd which is apparently common on 98-00 LS models so I didn't think much of it. Well now the gearbox shifts hard from 1st to 2nd also and I'm getting very annoyed by it. It even does it after the engine is warm. The transmission fluid and filter were changed at 112k miles because I wasn't sure if it had been done by a previous owner and the service tech said the fluid wasn't burnt but was ready for a change. There were no codes so I am at a loss here, folks. Should I take it back and scan for codes again? These transmissions are said to be some of the most reliable on the road.

 

what type of fluid did your service tech use? from my experience these transmissions are sensitive to fluids and only OEM toyota type-IV works best.

 

When I had the transmission serviced after I purchased the car, the tech said they put Toyota fluids in it. I mean it was the Lexus dealer who performed the work.

 

oh ok yeah if the dealer serviced it i would think they used OEM type-IV. for now check the level of the fluid. there is a warm level and a cold level depending if the car was driven (warm) or sat all night (cold). inspect accordingly.

i would next inspect the driveline, such as the driveshaft and associated bushings. also inspect the transmission mounts.

 

I'm actually at a local suspension and drive train shop right now. My family has gone to them for years and they do great work. And they don't charge anything for a diagnosis unlike Lexus.

 

They couldn't find anything wrong with the driveshaft or it's bushings. Nor did they find any issues with the front suspension I was also curious about. How do I check the tranny mounts?

 

At 120K I'm sure it would not hurt to do the mount. You need to visually inspect it to tell for sure. They are pretty cheap.

Your hard shifts are mostly likely due to failing solenoids if your fluid is good. Pull the pan, look for metal shavings. Replace shift solenoid next.

 

before you start diagnosing solenoids and all that good stuff, check the service record to see if it was just a drain and fill or if the transmission filter (screen) was cleaned or replaced.

 

if the hot and cold dipstick levels don't agree (and they sometimes don't) remember a little overfilled on this particular Aisin design is fine, whereas a little underfilled is much more of a problem.

I can't think of any as reliable.