I have a '98 LS400 that I purchased two years ago with 105K on the clock. I am presently just shy of 114K.
At the time of purchase I had the dealership do the following:
1. Engine mounts.
2. Transmission mount.
3. All four struts.
4. Transmission service.....They only drained the pan and refilled, no flush or dropping the pan.
5. Bled the brakes.
6. Changed the P/S fluid.
7. Lube, oil, and filter change....Air and cabin filters also.
8. Rear differential fluid change.
9. Coolant flush.
10. I replaced the fuel filter 3K miles ago.
I then replaced the tires and had an alignment performed.
The timing belt, water pump and tensioners were replaced a year earlier at 96K. The car was in tip top shape.
Ever since I've owned the car, I've noticed a trait I wasn't really happy with. When cold, I would back out of the driveway and place it in drive. I would feel the transmission go into gear, the back end would drop some, then I'd feel an extra small bump and small surge forward. I never thought this was good. I noticed that the transmission would not shift from 1st to 2nd until 25 miles per hour. I believe that this is a built in programming to allow the transmission or engine to warm up. However, it will only do this once. After these two initial issues the transmission would perform pretty well.
1st to 2nd shifts would be very smooth, 2nd to 3rd would, and is, the hardest hitting gear change, this has concerned me as well. 3rd to 4th, and 4th to 5th are very smooth.
About two weeks ago I started to notice that I was getting a harder than usual downshift into first gear when coming to a stop. This was happening intermittently. I was starting to take notice.
Two days ago, I had an appointment not two miles from home. I went, parked, concluded my appointment and proceeded to go to another appointment I had just around the corner. While driving just down to the end of the park lot isle, I had to stop to turn left. Right when I came to the stop the transmission downshifted to 1st with a pretty aggressive bump and lurch. I gave it some gas to move forward, but there was no movement. The transmission was in a neutral state, I revved the engine just a bit, maybe 1500 RPM, I didn't want to take chance of burning the clutches. The transmission engaged, but not totally. I was able to nurse the car around the corner to my next appointment.
After my appointment was concluded I raised the hood, started the engine and checked the transmission fluid. The fluid was full, the color was a brownish/reddish color, not too bad. The fluid did not smell burnt. I decided to try and drive home. I did not have an issue driving home.
I decided to go ahead and flush the transmission fluid. I took my wife's car and purchased enough transmission fluid to flush the transmission. I purchased Valvoline Maxlife DEX/MERC transmission fluid. Now before you get up in arms, this fluid is completely compatible with Toyota T-IV fluid. I did plenty of research on this issue. I've used it in my wife's car for over 40K miles and not a single issue. I believe in the stuff. I also own a SUN Mfx Xtreme transmission fluid replacement machine.
I still don't know why I did not do a flush on the Lexus transmission when I bought it. Perhaps, I was leery about having issues after flushing the fluid, since I've heard from people saying that the clutches may fail. Fail because the junk floating in the old fluid keeps the friction up. I believed the hype, and figured if the transmission started having issues, I'd flush her. Now, here I am.
Well, I flushed her out and drove her. The shifts were noticeably smoother. I let her cool down while I serviced my wife's car, and drove the Lexus again. I still had a small bump when I went from reverse to drive when it was cold. However, the shifts still felt better, and I didn't feel any slipping.
Yesterday morning I wanted to drive her again to see if there was anymore improvement. This time, there was no extra bump when going into drive for the first time, and I don't remember if the transmission held the shift until 25MPH, I wasn't paying attention to that at that time. The shifts were still very smooth except for the 2nd to 3rd gear shift, still the harshest shift. The downshifts felt pretty good, I didn't feel any that were reason to be concerned about.
I did have one time that I thought the transmission might have slipped. I was starting from a stop light, I was behind another vehicle that was going pretty slow. I had to let off the gas, and then I was feathering the gas a little bit, and thought I felt it slipping a little. Really, it could have been my imagination. The transmission seemed to do well.
So now she is parked in the garage, I have yet to drive her today. I think I will drive her for the next couple of days to see how the shifts are doing.
NOTE: I did NOT have a "Check Engine" light when the transmission was acting up.
I did talk to my Lexus dealer and a local Toyota dealer to see what worst case scenario would be for replacing the transmission. Oddly enough the two quotes were almost identical, about $3800. The Lexus guy was surprised to hear that I was having issues with the transmission so early in it's service life. He stated that these transmissions are pretty darned bullet proof.
Now I'd like to tap into the collective knowledge of the board and ask for some advice.
1. If I still get the bumpity-bump when first going into drive, and getting a harsh 2nd to 1st downshift, or slipping, should I replace the 1st to 2nd gear solenoid?
2. Are other people having a sharp 2nd to 3rd gear shift? If not, should I replace that solenoid as well?
Or if anybody knows of some other fixes for these symptoms, I'd love to hear them.
Sorry for the long winded write-up. I just wanted to give a concise clear history.
Thanks for your time and help with these issues.