2004 LS430 with 137K miles. As far as I know the transmission fluid has never been drained and refilled. My LS has begun developing transmission shift issues, it would once in awhile seems to be stuck in a gear and not shift to the correct gears. The only remedy is to turn the car on/off. For example, the car would reach RPM 4K at 40 MPH and the transmission would not shift gear like it normally do and drop the RPM to 1k to 2k RPM and if I take the car to the freeway the RPM would reach 4.5K RPM at 60 MPH which normally is at 2K RPM. Any suggestion is appreciated.

 

Did your Malfunction Indicator Lamp (Check Engine Light) come on? Have you tried to pull DTC (Diagnostic Trouble Code) from memory?

 

NO CEL or any other indicator. I'll hook up my laptop and see if I can obtain the DTC. Furthermore, I have tried to disconnect the battery for few hours hoping things would reset to no avail.

 

The LS430 transmission shifting is controlled by an ECU via a series of solenoids using the ATF as hydraulic fluid. The health of each solenoid is monitored by the ECU and any failure is logged with DTC. This can narrow your troubleshooting effort. Unfortunately, the ECU cannot detect a clogged solenoid.

 

I run Health Check with Techstream and it came up with 5 DTC ABS\VSC\TRAC codes but the only one the remotely pertains to transmission is DTC code U0124 "Lost Communication with Lateral Acceleration Sensor Module". Unfortunately, It didn't provide any time/date stamp. The rest of the DTC ABS\VSC\TRAC codes pertain to ABS C1223, Control Module Bus OFF U0073, Yaw Rate Sensor U0123, Steering Angle Sensor U0126. The rest of the DTC codes are Air Conditioning related.

RKW, do you suggest I replace the ATF fluid first and see what's the outcome?

 

Sounds like the solenoids are functioning properly. If this were my car, I would start with drain-and-refill and make sure the ATF is at the proper level. Do not perform a power-flush since it will worsen any clogged passages already developed.

 

Not proud to announce this, but I neglected to change the transmission fluid in my '03 for about 10000 miles over the recommended service interval and it started to behave like this as well, especially in cold weather.

It's been over a year since it was serviced now and changing the fluid definitely fixed the issue. I guess it's some sort of fail-safe mode for the box when it's having a hard time shifting or something? Either way, I'd say that's your best bet.

 

It has been over a week and my transmission issue hasn't reoccured. Nevertheless, I put my car onto Rhino's ramps this morning and drain and refill the transmission fluid in the evening after work while the transmission is cold. Only 2 qts came out. 2 qts seems low, I was expecting 3 qts. I didn't see any transmission fluid leak. Can it be some transmission fluid evaporated or burned? I did read rkw77080 "Getting ready to do a drain-and-refill on my 04 LS430" thread how to check the transmission fluid level but unfortunately I have no way to level the car while lifted. Any advice appreciated.

 

This may help if you are working on in a garage or driveway that has a small incline. Both of my driveway and garage is not level. If I need to do anything in the front of the car, like oil change, I would park the front of the car facing the slope. I then raise the front of the car so it is level. It is tight but enough to give me room to work under the car.

Do set parking brake and use tire chocks as the car can roll away.

 

Appreciate the advice but I don't have any uneven surface on my drive way. I am wondering if I put the air suspension on "High" I have the clearance to reach and loosen the overflow plug while parked on the ground. I already have an Infrared Thermometer gun therefore measuring the transmission temp at 115 F degree won't be an issue.

 

On the "Getting ready to do a drain-and-refill on my 04 LS430" posting, if you skip forward to Post #20 and #21, I proposed a work-around solution to gain a few inches of clearance by jacking up the car (one corner at a time with the OEM jack) and placing a 4" concrete block under each tire. Of course, use extreme caution and make sure each tire is resting squarely on the block with the hand brake fully engaged to prevent the car from rolling.

 

Putting the air suspension on "High" should give you enough clearance to reach under the car from the passenger-side to work with the over-flow plug. Adding the concrete blocks will give you even more room to work.

One very important note: The ATF level must be adjusted with the engine running, in other words, you are checking for the correct amount of ATF remains in the pan while a significant amount of the ATF is circulating through the transmission gears and passages. When the engine stops, all of the ATF will drain back into the pan, and if you mistakenly adjust (open the over-flow plug) with the engine stopped, you would have drained out too much. This (adjusting the ATF level with the engine stopped) may very well be the reason why your current ATF level is low. Hope that make sense!

 

Yes, that does make sense. I reread you old thread again and you did mentioned you had ample clearance with all 4 tires on the floor. If that fails the 4 comet blocks is a great suggestion. Once again thank rkw77080 for your suggestions.

I plan on doing 3 more drain and refill. I don't know if this will fix my transmission issue or not but the LS transmission definitely does feel smoother on my 32 mile drive today. For those of you with over 100K miles and have not done the drain and refill on your ATF, you need to do it. If you can do your own oil change, you can drain and refill your ATF. Just following the above link to rkw77080 thread. I feel is even easier than changing oil once your are familiar with the procedure. The hardest part for me was loosen the 24mm refill bolt (bought 24mm wrench from amazon for $17) since it was very tight and the transmission pan is partially blocking the wrench. I had to put the wrench above the pan for a good grip on the bolt. I bought 4 ft of 5/16 clear plastic tube from Ace Hardware for $1.60 and attached it to my old funnel for the refilling from above the engine bay. I bought an oil pump but didn't use it.

 

hmm... I was hoping there is enough space for a socket. Is a 24mm wrench a must have here? Asking because I only have socket for that size. I may have to order a wrench as well from Amazon. I doubt there is a local store carrying 24mm wrench.

I was planning to do this over weekend, but may take a peek tomorrow to see how much space I have down there.

EDIT: nvm. I did a quick search and found someone who said a socket is not going to fit.

 

I bought this combination wrench used for $17 from Amazon Warehouse . First I tried using the round end to loosen the bolt from the bottom but it kept slipping.Then I tried using the C end and it also slipped. I didn't want to strip the bolt by continuing from the bottom therefore I decided to put the wrench just above the pan to get a better grip using the round end and with a strong up push, it popped (counter clockwise is loosen). Once it's loosen you can easily remove it from the bottom using either end of the wrench.

If I had to get another wrench for this job, I probably get one with any angle like this . Don't over think it. Honestly, It's not that hard of a DIY. Did you know I puchashed the ATF WS oil over 2 years ago and never attempted to drain and refill because it looked complicated. Now I am having transmission issue. You can do. Just take your time. Good luck.