cristianhr

hey guys, I recently bought a 1995 Ls400 off a buddy for cheap. So the main issue is that it does not move in reverse when shifted into reverse and it seems to move forward a bit then just sit as if its in park I tried rocking the car back and forth and it didnt budge, and when it's in Neutral, it moves forward as if it were in Drive. All other gears D3, 1, 2, L drive forward as they should. i know D also seems to slip or rev up and then i have to release the gas pedal to let it upshift into the next gear, I don't know if that would be caused along with the no reverse issue. I dont have a MIL on and i connected my scanner and find no codes.
I have drained and dropped the oil pan to see the transmission fluid and to check for any debris or shavings but found nothing out of the ordinary. I also looked at the fluid filter and didn't see any debris stuck on it, so i put it all back together and refilled the transmission with fresh Toyota T-IV fluid. still the same issue.
I also had someone shift from P down to L then back from L up to P as i watched the gear selector on the passenger side of the transmission and it seemed to shift along with the shifter, but is it possible for it to be out of adjustment and still be shifting along with the shifter causing my issue? I've looked around and read about the park/neutral safety switch (NSS) and decided on trying to readjust it along with the selector but does anyone have a write up on how to do it exactly? I can't find anything on it for this gen ls400.
The shift indicator lights up all the correct gears and the car doesn't start in any gear other than P or N but would the NSS still be an issue? Could the solenoids be an issue? I also tried disconnecting the main solenoid connector on the driver side of the trans to see if I could then shift manually into reverse but that didn't change anything.

I've been looking around the forums searching for people with my same issue and have found some related but it seems people just disappear and never state whether it was fixed or how they fixed the issue. I'm hoping it's something that I'm just missing that than can be fixed without having to tear this transmission apart or having to replace it
Any ideas or suggestions would be appreciated

dicer

That's a difficult one with out the book handy. It could be the selector switch or reverse friction material problem, just not sure. Banshee is the now transmission expert on these cars he's overhauled a few of them.

oldskewel

iTrader: (1)

Excellent description - you addressed all the initial tests and procedures that most people would advise. I agree with dicer, hopefully banshee will see this and know the answer.

My understanding is that '95 was when Lexus put OBD2 in for the first time. If they still have remnants of the previous system, maybe there is a second way to get codes out - jumpering and counting flashes like in the older cars. And maybe you could get a different/better look at transmission codes that way. Just a guess.

Is everything else good except for reverse? If so, you might try driving it (yes, reverse is optional if you plan carefully) to see if the new fluid changes things, like perhaps freeing up a stuck solenoid.

cristianhr

Yea all gears work except drive, even N drives forward. one thing is when im in R it just sits like its in park, so i have to shut off the engine, then put it in N and then i can roll it in reverse out of my driveway. i'm gonna give that a shot today and see what happens and see if i notice any differences when driving it around. For the codes I'm going to have to look into that and i might just ask my buddy to bring his scanner by to see if i can pull any transmission codes, hopefully i find something.
I came across one of Banshee's posts also he seems like he knows what he's doing.

cristianhr

I also read about ecu's being an issue, so i opened up the ecu but everything looked fine. unless i'm missing something.

cristianhr

I don't have any books but i do have access to AllDataDIY for the car so i'm just looking around on there for now.

oldskewel

iTrader: (1)

Did you have some typo's in the above? (swapping D for R, for example)

"N drives forward" - as if it's actually in D? Well that's a clue.

R is like P - that's another clue.

Is there a chance that the cable is somehow not providing the desired selection at the AT? Either a problem in the shifter, cable, or AT-end of the cable, so when the shifter is in R, you're actually in something else like N? I know you said above how the PRNDL lights in the instrument cluster are working fine, but I'd still double check this area.

cristianhr

sadly no typos there man haha. So i think i've narrowed it down to it possibly being an internal issue in the transmission. I pushed it out of my driveway to go for a test drive. So i noticed when shifted into P the car moves a tad bit forward then does park but seems to idle down as if its in a gear, That might be normal in these cars? I don't know.
I can drive in N but it feels like its just one gear, it never shift, and i noticed as you drive it seems to slip. When in D3 it drives then revs high until I let off the gas, and then it will shift to the next gear but i dont feel any slipping. 2 and L seem to drive as they should.
When shifted into R i can literaly give it gas and it will drive forward, then it will will just catch and lock as if i smacked the shifter into Park. i tried this several times during the test drive and did it every time.
It seems like no matter what gear i was in, they all wanted to go forward.
So i guess its time to start looking for a new transmission? haha

billydpowe

iTrader: (1)

you might consider professional help... having been a pro......

cristianhr

yea I'm no pro for sure but I'm also not sure what you mean with that Picture. Are you saying that solenoid could be an issue?

Yamae

You'd better to think a bit more logically.
See the solenoid chart attached below although it's for a A650E. Just disregard S4 and think what happens when S1 is always OFF.
When the solenoid S1 is failed to work and is always off, it causes No reverse as well as the neutral works as the 4th. This must be your problem, I bet.

2013FSport

iTrader: (2)

Seems like a win here. Test continuity and then pull them and verify they move when 12V is applied.

How exactly did you verify the alignment of switch and detents? I would remove the cable to the trans and use the alignment pin (usually while in N) and align the switch.
For the most part when in N, there should be NO pressure applied to ANY bands or shift drums. So, something seems wrong here like the trans has a stuck valve or it is not actually in neutral. In rare cases, something could have bent the mechanism therefor the External lever on the trans is in fact in Neutral, but internally the valve body is not in Neutral or completely IN or OUT of any desired gear.

Read up on the oil control circuit needed for each gear. It should tell you something about this.
Another possible option is a band has snapped. For reverse, drums are stopped by band clamps actuated by pistons. Thus it makes me wonder if band on a drum snapped off an end therefore a drum that is supposed to be locked for reverse to occur and some ranges of forward motion, well if the bands end snapped this is possible to have no motion.

So, with the valve body off and map of which oil passage goes to which drum and which band and you can use a air pressure and a rubber tip on some passages and apply say 50psi of air and A) test for leaks. B) verify that said drum or band (bands using pistons), apply and grip the drum.

billydpowe

iTrader: (1)

did you open up the PDF file and do any reading????? why do you think I put it in for??/ you just want someone to do it for you, I want you to get in there and read and think like yamae said...... think it over..

oldskewel

iTrader: (1)

I'm curious too, Billy. You have a photo of the AT with the pan off. And a PDF on how to R+R the wiring harness with temp sensor. With no explanation.

I know some on this site like to present puzzles when people ask for help, and I do understand the reasoning behind that. And I'm usually good at puzzles, but am still stumped by yours.

Are you suggesting it is the wiring harness? The temp sensor part specifically? Or are you just suggesting to take the pan off, inspect things, and change the filter (also included in that 3-page PDF)? Is there something specific in the photo that is a clue?

And if the answer is that you do think the wiring harness needs to be replaced, some explanation as to why would probably be helpful. Not saying at all that it's wrong, but most smart people don't just take advice and follow someone else's instructions without thinking and understanding it. And me, I'm just interested and trying to learn, just because.

billydpowe

iTrader: (1)

[QUOTE=oldskewel;9984968]I'm curious too, Billy. You have a photo of the AT with the pan off. And a PDF on how to R+R the wiring harness with temp sensor. With no explanation.

OK, I am only trying to get him some help, and get him involved... I am 83 and I have a friend who is almost my age and he had a tranny shop in my city. He had a LS400 eating him up, pulling in reverse with no neutral and they replaced the harness and the ALL the solenoids out of another trans. trying to solve it and it worked.. he didnt know if it was one or the other, was just happy to have it fixed... so with modern eqpt you should be able to test the solenoids AND the wiring contacts and find the fault..
this was several years ago, and like me he forgets... BUT not trying to be smart.... just pointers, that chart of Yamae's should help..