lalaland

recently this has been becoming worse, but when i switch from neutral or park to drive, it is really hard and the car feels like it was just neutral dropped. however after this initial hard shift, the rest of the shifting is fine, what could the probelm be and the fix is possible

i think this has been discussed before but i have been unable relocate the thread by browsing and searching

lalaland

anybody know a solution?

chrisman

hi,, it could be many things,, but go over basics first.. make sure it has good oil level--and when or has there ever been a trans service done--replace filter and oil?.. also make sure the cable going to the throttle from the trans is not stuck.. this controls the pressure the trans has--i believe its called TV--Throttle Valve cable.. if for some reason the valve is at its max, the trans would engage harshly--just like you described--but, it would also shift harshly, but that may be less noticeable..

lalaland

thanks for the reply

oil level is nominal using proper toyota auto fluid and no tranny work has been done to date,

where can i find this cable/valve you speak of and check if it is full open or close, i suspect siezed bearings or whatnot

rdm20fan

Do you have an SC300, or 400?
Chris, are they the same? No right?

On my early SC400 it is right next to the throttle cable, on the throttle body.
The throttle cable, and trans cable come from the drivers side, and the traction control comes from the pass side so there are 3 cables total.

chrisman

yes,, bob is right.. on the sc400 its where he described.. i believe, but am not positive,that the sc300 is very similar.. as far as i know, the supra transmissions are a little different..

lalaland

yes mine is a sc400 and erly model, what exactly should i be looking for though?

thank you

chrisman

on the early sc400 trans,, like most trans, the pressure is made by thepump.. then the pressurized oil is regulated--i believe by a total of 2 valves--after which, the the Throttle Valve regulates the oil pressure before it applys the clutches.. --that all being said,, it could be any one of the above things-BUT- it may be something as basic as low oil level-or an old trans filter, etc..
something else i didint mention is the accumulator--it kinda acts as a schock absorber for the oil pressure-especially when engaging gears.. on that trans accumulator pressure is controlled by a solonoid which is modulated by the ecu.. if, for example, the solonoid is not working correctly,, it could produce hard shifting.. also, i believe lexus uses the solonoid to " reduce squat" that is the sensation of the car squating when first put in a forward gear.. solonoids are known to fail, or not work perfectly when they start failing..
i hate making it sound complex,, thats why i suggest go over basics,, and then if the problem pesists, you can get deeper into the trans.. ,,if you feel comfortable doing your own work, and have patience, you may be able diagnose it as well as anyone..maybee without going into the trans..

lalaland

oo i havent checked this thread for a little while, busy with school

thank you for the advice and i will check it, any advice on where to find/troubleshoot the parts mentioned

tttp5

iTrader: (1)

sorry to pull up an old thread.

the problem I'm having is when I shift from N to D and I have my foot on the brake the car seems to want to lunge forward. When I'm driving and I apply the brakes, as the car almost comes to a stop, between 10-5mph i would feel the car lunging forward slightly too as it downshifts from 2nd to 1st, I know its downshifting because u can see the tach needle rise just slightly and then fall back down again.

I read what chrisman said and I'm kinda sure my problem isn't to do with the fluid level and wrong fluid because I just got the tranny flush a few months back.

could you tell me what i would look for or how I would adjust the Throttle Valve cable back to stock settings.
or, what would I be looking at to replace the soleniods. I'm not a mechanic but then at least I could tell my mechanic friend what to look for.

thanks.

Fern

If you have a mechanic friend, have him drive and diagnose the problem.


My 1999 Rx300 showed the exact same symptoms as yours.

I'm having my trani rebuilt at Toyota with just 138,000 km and 2 drain and fills with T-IV since new and internal trani failure

Very dissappointed...

Take it to Toyota or Lexus for professional diagnosis and post their opinion.

Waiting to here results.
Good luck,

Fern

lalaland

yeah, such an old thread i forgot about it....

but either way probelm has been resolved in two parts

1) power flush of tranny using Toyota T IV (since i bought it used i didnt know how long ago was last flush)

2) lubrication + constant moving of that shifter cable (lube + pump on gas when car is off + repeat)

probelm is "solved" cause transmission is pretty smooth, however since i back off the the cable it doesnt move much and gets stuck again from time to time (proabably corrosion). i just restored cable to previous setting and let you know if this probelm occurs again