90 Ls 400

[tonyvang]

first time posting on this forum, i know you guys heard about many times but cant seem to find the problem. The car jerks from park to reverse and to drive,,, but it only does it when its warmed up. This is my first lexus so im not sure where to start. Any help is greatly appreciated. THANKS

[steve2006]

Hello and welcome to the LOC.

Assuming the warm engine idle speed is correct at around 650 RPM.

First check for me would be transmission fluid level as detailed in your owners manual then check the condition of the fluid itself.

The fluid should be a dark cherry red color, if it's brown or smells burnt it needs replacing.

The fluid is a special Toyota mix called Type IV do not use anything else.

The stuff is available in quart bottles and is cheaper by the case from dealers.

For more information on replacement have a look at the tutorials on www.lexls.com.

[LSPaul]

Alternately, if you can't lay hands on genuine Toyota trans fluid, many auto parts stores carry Mobil 3309 fluid (accept no substitutes), which is also T-IV spec.

Paul

[tonyvang]

Yes I had Toyota change the tranny fluid I'm wondering if they messed up something and didn't tell me.

[steve2006]

In that case you may have a problem with the shift shock system, basically Aisin transmissions have this system to reduce the jerk when going into drive by 1st taking the transmission into 2nd before 1st.

It could be sticking solenoids but if this is the only problem and given the cost of repairs I would live with it on a 23 year old car.

As I asked before is your warm idle speed correct at 650RPM? if this is high this will cause a jerk.

[tonyvang]

Yes the car is at 650RPM ... as far as the sticking solenoids is that a fix able problem? Also I notice I can shift from park to drive with the car off. Never had a Lexus before so Im not sure how to handle this problem.

[fsuguy]

I would suggest following the tips about the fluid first - if those are up to spec and your idle is fine, then you may want to check the solenoids.

There are four solenoids and either the 3rd or 4th on serves to damp the shift shock - don't recall which one.

The first two solenoids are for the gears shifts and are identical to each other. The 3rd and 4th have longer necks and are different. Replacing them is fairly straight-forward if you have a means of raising the car high enough, and are reasonably competent with ordinary hand tools. It will involve removing the transmission oil pan (19 10mm bolts), and getting a new pan gasket or Toyota sealant for the form in place gasket (recommended); while doing that you may also want to change the oil filter, or at least thoroughly clean it - it is a metal mesh type and easily cleaned. Removing the solenoids and filter is merely a matter of undoing readily visible and accessible bolts once the pan is taken off.

Couple of things to keep in mind if you decide to change your solenoids -

1. First drain out the pan - this will take some time, so be prepared to wait for a while! Once drained the pan cover will have to come off - if the pan has never been taken off, the seal will most likely be hard and you may need to break that with a gasket seal tool; use it carefully to avoid damaging the sealing surface. Once the pan is removed the rest is a piece of cake!

2. The wire harness which connects to the solenoids have plastic clips that will be brittle due to heat and the oil and are more than likely to snap off while removing the clips from the soleoids, so beware of that; if the clips snap off, keeping the connectors securely attached to the solenoid will be a challenge - a replacement harness is available from Sewell for about $25.00, but you will need to be able to identify the correct harness number when ordering it (very confusing so do your homework beforehand - I have posted the part number on this forum somewhere); also the surface that mates with the pan is aluminium and can get scratched if you are not careful removing the old sealant - be very careful about not scratching this surface when cleaning it - gouges and deep scratches will cause the pan to leak fluid and drive you bananas over time! Also, do not over-torque the pan bolts or you may strip the aluminium threads.

3. If you go the FIPG route, follow the directions for drying/curing time carefully;

4. Replace the drain gasket/ crush washer with a new one;

5. Finally, it should go without being said, but replace the fluid with new Toyota Type IV fluid to the correct level;

If the solenoids have never been changed, then you may benefit from getting a set; these are not cheap - about $280.00 for each one, unless you can get them directly from Rostra (they will sell to jobbers, so if you happen to be friends with one it may help!).

Hope this helps, and good luck

[tonyvang]

Thanks for all the help.... I will be checking on those this weekend.. THANKS AGAIN!!