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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
Did you finally get it fixed? My GS 430 has the exact same issue and I'm trying to review all my options before I decide to replace the whole gearbox
Hey guys I too been struggling with my 92 LS400. No reverse gear. Drives in neutral. Will only engage neutral with engine turned off and the shift over-ride button engaged to manually select neutral (Also reverse acts like neutral in this manner)
Checkout my attached related repair manual documentation for some clues. Please one of us MUST get to the bottom of this!
This documentation for 92 LS400. For exact year and model documentation get a membership at https://techinfo.toyota.com/
By the way I have already tried these things for my 92 LS400:
-Replaced ECU
-Confirmed console shifter and associated lower linkage gear select positions are correct to detent (A341E tranny)
-Tested tranny solenoids along with correct resistance values S1 S2 S3 S4
-New Toyota gear oil and pan filter (no metal shavings on magnets, filter ok, oil ok and not smelly, oil level ok)
-Ran car without electrical connectors on transmission (Still having no reverse issue as described)
The next battle is to find out if the NSS (neutral safety switch) circuit could be causing false reading to ECU as the NSS appears to be the sole electro-mechanical output device for gear selection off the tranny (Despite the matching gear is always correctly selected at dash) OR if issue is actually downstream with circuit between dash to ECU. Lord only knows
-Tested tranny solenoids along with correct resistance values S1 S2 S3 S4
Those solenoids can't be fully checked by the resistance value. There often happens a mechanical movement problem which commonly happens among OCVs for the VVT-i. The resistance measurement is only a part of trouble shootings. The best way is to check movements. But this needs to remove solenoids. I usually do the sound check before the removal applying the DC10V to solenoids each. A weak solenoid doesn't sound right.
Those solenoids can't be fully checked by the resistance value. There often happens a mechanical movement problem which commonly happens among OCVs for the VVT-i. The resistance measurement is only a part of trouble shootings. The best way is to check movements. But this needs to remove solenoids. I usually do the sound check before the removal applying the DC10V to solenoids each. A weak solenoid doesn't sound right.
Thank you Yamae however I have done a sound check - they have a healthy sounding click to them. I used a 12 volt SLA battery as a power source for the bench test
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
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
I have the exact same problem on my 1997 word for word. Did you ever fix the issue?
Removed the valve body and replaced solenoid 1 and 2 as part of my first transmission job on 1994 Lexus ES 300 (A541E). Then had the same symptoms. All things seemed to do 1st gear and no reverse. Took it apart and found that I missed connecting the manual valve body shaft to the shift selector. If the shift selector does not move the manual valve body you stay where the valve body was. For me 1st gear. If you have a broken shift cable to the outside of the transmission I bet you'd have the same symptoms. Drove me nuts trying to figure out what was wrong. Hope this helps others.
imagine my surprise seeing this post-- i just watched a youtube from Pine Hollow Auto Diagnostics with almost exactly these symptoms and the fix in the end (3 episodes long).
I have the exact same problem with my 01 GS430. All forward gears work; sometimes in initial drive high rev in 1st gear, but settles out in a few seconds. Neutral drives forward in 1st gear, Park actually seems to engage a forward gear just before the locking pawls engage so the is a jerk going into park. An additional thing is that even though there is no reverse, the reverse gear does seem to hold some forward "action"....when in reverse, I cannot push the car back, but when the engine is off, I can roll the car backward.
I have read the chart about the solenoids, but since all forward gears work fine, i THINK that means all solenoids do go off and on, otherwise the forward gears would have some kind of problem. I have read about checking the Park Neutral switch, but the car does only start in P and N, so not sure what else I would be checking with regards to the switch.
If the original poster would provide some solution/direction, I would appreciate it.
My next step might be what the 83yo mentioned and just put a whole different used valve body with solenoids in and see what happens, but that would be out of frustration rather than well thought out logic.
BTW first post so hope I got all the info in.
I have a 2002 gs430 and have the same exact problem only thing is it started actin that way after I put my tranny back in after replacing my seals and torque converter before pulling my transmission I had a check engine for shift solenoid malfunction my reverse and all gears worked perfectly fine before that even with the code on after putting the transmission back in and turning it on for the first time immediately neutral and reverse would not work I neutral it still moved forward as if being in drive but in reverse it would stay still but still rev up as if it was in neutral but the check engine code cleared it wasn’t till I took the car outta town for the first time that my shift solenoid malfunction code popped up again. when I shift it into gears the car jerks a lot also especially when I put it in park and when I turn the car on and off when in park and I try to rev up it’s sluggish almost as if the car is still in drive one time the car actually moved a little forward while revving in park it read all gears correctly on the dash could it be my shift link or my malfunctioning solenoid the car only has 152k miles I don’t think my transmission is going out, any info would be highly appreciated
Other than the solenoid S1 issue, the failing speed sensor sometimes causes the problem, I need to add.
Those who were not successful to fix the "no reverse and neutral drives forward" problem dealing with the solenoid S1, it may be an idea to check the waveforms from the speed sensors or simply replace them. Usually output side of sensor fails more often than the input side.
These are the actual waveforms of in and out of the AT's speed sensor.
Last edited by Yamae; Oct 20, 2022 at 11:43 PM.
Reason: To add actual waveforms
Fixed
