Hey everyone!

I've got two (possibly related) transmission problems with my '99 GS400 (193K) I hope you can help me with.


(1) I've got an intermittent issue when I come to a stop. Sometime I can feel the car struggling to downshift (I think?) which seems to prevent the car from slowing down properly and sometime can now result in a small jump forward (usually when around 10mph).

Simultaneously I can see my RPMs spike during this transition. Now that I am aware of the issue, I tend to keep more distance so I can decelerate more gradually and compensate for any "jolting" forward. It is a manageable problem for now but is becoming more frequent. I notice this happens most often when I have maintained highway speeds for a prolonged period and am coming to a stop.

(2) This is more of a quirk than a problem, but I notice every morning when I start my car and I am accelerating for the first time, the first gear it wants to shift into takes a very long time and can result in the car getting stuck around 2200 rpm before finally shifting. After this, any upshift/downshift seems relatively normal.

As a result, when taking off in the mornings I have to give it a little extra gas to get it past that first problematic shift. I've tried letting the car warm up and that seems to have marginal effects.

Additionally, while driving around town or in stop-and-go traffic it seems like my transmission gets confused somehow and tries to upshift or downshift at weird times, resulting in a "clunk" for lack of a better term. This issue has been present since I bought the car 5 years ago, but is slowly getting worse.

- I have checked my transmission fluid quality and level (looks great!)
- Fluid was changed 45,000 miles ago (should I go for a change?)
- No CEL

Thanks in advance!

 

definitely change your fluid a few more times. Drain and refill as many times as you can and that SHOULD help the problem. Technically the fluid should be changed every 30k miles so you are due for a change regardless. Since your experiencing these issues, I would drain and refill and drive for a couple weeks, then do another drain and refill and see what happens.

 

I personally get your #2 problem whenever it's rather cold out but it always goes away after a couple minutes of driving. as for the second part of #2 or maybe a third problem I've had a Vehicle Speed Sensor go out and it behaved the way you described BUT it will throw a CEL, so I kinda doubt that's your issue. and lastly I do my ATF changes every 25k

 

I'd definitely get it changed bro. Sounds like a good flush of the system ought to be done. I hate to admit it but the Lexus dealer has the best equipment to properly flush the tranny out and suck out all those lil metals. I took mine about 2 years ago I believe. Like 15-20k miles ago. I use to have that similar jerky feel between gears. It's gotten better since then. I will take it back to the dealer sometime this winter. I paid like $280. I know that sounds crazy when you can just drain the tranny yourself and all that. But the machinery they use is what made me take it there. Your choice. My advice is pay the $280 and get it done at the dealer and stress to the service department to get it done right and thoroughly as I did. Let them know your conscious about your vehicle and it's condition. Good luck brother. Let us know how it all went.

 

I personally won't advise a flush. most times that leads to disaster. just drain and refill a couple times

 

Second that

 

I would also recommend you do a drain and refill only as well. I just did that a few days ago and shifts are so smooth now and only with a few quarts of new Toyota transmission fluid.

 

Thanks for the advice guys!

I'll probably just drain/run a few times and see if that works and report back. Since the car is so old I don't want to risk a flush causing a problem. If it were a younger car I'd probably go for it though.