GrantB

Hello, im having some issues diagnosing what is causing my issue. The car is a 1991 LS400 with 295k on the odometer. The shifter works great, feels like the detent is working properly and goes forward and backwards through all of the detents with minimal effort. The transmission seemes to be stuck in forward no matter what position i put the shifter in although some features still work. Here is a little diagram that i hope will explain my issue.

Park-Car is locked in place but i can feel the driveline load up when starting or a few seconds after.
Revers-Car will roll forward about 1 foot then the park lock stops the car
Neutral-Car will move in 1st gear and maybe even shift into 2nd. Although only done this once ore twice by accident.
Drive-Works properly
2-Limits car to 2nd gear properly
L-Stays in 1st

Another thing i want to add is when coasting the car is obviouly still in gear. If i go down a hill the engine will provide braking and the rpm's will stay up just like in a manual car. In all other auto cars i have driven when shifting from park to drive(with foot on brake) you can feel the transmission engage in this car you can barely feel the doughnut/rag joint flex. Ie its always in drive.

I decided to pull the pan while i was doing my oil change and everything looks pretty good inside. The fluid wasn't as red as new but i would not say it was burned either. There was some slight buildup of material on the magnets in the pan but over all im very impressed with how clean everything is for its age.

Im kinda thinking one of the solenoids are stuck but the new ones are a little to pricey to just replace IMO.

Any feedback is appreciated.

Thanks,
Grant

LScowboyLS

please put the car in park, key on in run positon, but car off - OD button on, and jumper terminals Te1 and E1

follow the instructions on reading the codes from the link above, and then post the codes you get

it could be something as simple as fluid level or incorrect viscosity, or it could be a solenoid, or other transmission issue, but a surprisingly common cause on older LS400 is failing ECU capacitors (maybe not so surprising when you figure that all transmission control in your LS is done by the main ECU)

GrantB

Thanks for the quick reply and helpful link!

So I was able to pull 3 codes 46, 62, and 63. They were all solenoid shorts so I figured it might be because I pulled all four solenoids. After replacing the front two and loosing 46 then the back two and loosing 62 and 63 I now haveno codes. I'm kinda wondering why I only threw three of the four codes possible for an open or shorted solenoid. I am kind of intrigued about the ecu issue since I have had that same issue with a dsm a few years back. I will order the capacitors and hold onto them for a later time

I'm going to button the car back up and will report if there are any changes.

One thing I forgot to add. The car had speedo issues and the dealer replaced the trans mounted vss twice. The car sat after this and that's when the trans started refusing to go into reverse. That's about all I know from the owner who is starting to loose his memory.

Thanks!

LScowboyLS

it is exactly the same issue as with the DSM cars and exactly the same cure, capacitors don't like the car to sit, besides, these capacitors in your Lexus have a known defect, please read post #8 from famed Japanese engineer Yamae in my ECU thread

I predict you will be installing those capacitors before Halloween! (probably before Labor Day - lol)

LScowboyLS

also, before going any further, please inspect your car for the following very common issue that can wreak havoc and is an easy fix: