No reverse and Neutral drives forward
09-18-17, 04:04 PM
#16
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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.
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.
09-18-17, 04:23 PM
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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.
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.
i Will be doing some more research on this for sure. I'm going to need to get my hands on a voltmeter this week also once i have some extra time on my hands
09-18-17, 04:37 PM
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I did open the file but i just didn't understand what you were indicating with the picture of a circled solenoid and the pdf file. I already dropped the pan and checked the strainer and magnets and cleaned them up as i stated before.
Last edited by cristianhr; 09-18-17 at 05:11 PM.
09-18-17, 04:43 PM
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[QUOTE=billydpowe;9985123]
I appreciate that, like I said I'm simply here to get some helpful information. and Yamae had a very valid point witch was something i was concerned about i just have been having trouble finding procedures for all of this on an ls400
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..
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..
09-18-17, 06:36 PM
#20
[QUOTE=billydpowe;9985123]
That makes a lot of sense now. Thanks for following up with the supporting story and some details.
And combined with the specific table from Yamae ... cristianhr will need to find the corresponding one for the LS400, but Yamae's table should be a very good clue that a single solenoid failure could cause the multiple weird symptoms he's seeing = something interesting I learned here, which is why I read these things even when I don't have the specific problem (yet).
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..
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..
And combined with the specific table from Yamae ... cristianhr will need to find the corresponding one for the LS400, but Yamae's table should be a very good clue that a single solenoid failure could cause the multiple weird symptoms he's seeing = something interesting I learned here, which is why I read these things even when I don't have the specific problem (yet).
09-18-17, 09:30 PM
#21
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[QUOTE=cristianhr;9985312]
So you understand what is behind your problem. I believe that a A340e uses the same solenoid table with a A650 except S4. Attached is wiring diagram for a JDM Celsior but a LS400 95-97 shares almost the same diagram.
Check the voltage and the continuity indicated by the red arrow which can be seen a bit left and upper part. It is the driving line from the ECU to AT solenoids. You also can find which pins and the connectors are related seeing the blue and the green arrows at the bottom part. Small red circles indicate the related pins.
Correction: Just disregard the red circles at pin 7 and 8 at right bottom corner. These are for another issue. In your case, pin 4 and 5 are related since these are connected to the solenoid S1.
Check the voltage and the continuity indicated by the red arrow which can be seen a bit left and upper part. It is the driving line from the ECU to AT solenoids. You also can find which pins and the connectors are related seeing the blue and the green arrows at the bottom part. Small red circles indicate the related pins.
Correction: Just disregard the red circles at pin 7 and 8 at right bottom corner. These are for another issue. In your case, pin 4 and 5 are related since these are connected to the solenoid S1.
Last edited by Yamae; 09-18-17 at 09:36 PM. Reason: Correction
11-11-17, 05:03 AM
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Any Joy in fixing no reverse problem?
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 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.
11-11-17, 07:01 AM
#24
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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 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 would drop the pan and check the S1 is stuck or not.
11-13-17, 03:20 AM
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Yes all forward drive gears work. S1 solenoid?
yes, all forward drive gears work. There is a slight hesitation to upshift from first gear on initial drive of the day, but otherwise all forward/drive gears seem fine. The gears shift with a corresponding increase in speed and shift with drop in rpmsjust as it did before the reverse problem.
Shift linkage-I have assumed that the shift linkage is fine because the shifter can go from park all the way to 1, and the parking pawls engage in the park shifter position, and when shifted to 1 it begins and holds in 1st gear. Also the car will only start in the P or N shifter position. What other ways should I check the linkage?
S1 solenoid-I have seen the previous post in the thread about S1 not functioning, but since the other drive gears seem to be fine at road and highway speeds; I did not see the logic of the S1 being stuck because the drive gears go through the sequence, which involves S1 switching on and off. I will definitely check, but I just did not see how S1 could be the problem.
This week will be one of the last weeks I have to figure this out so I wanted to have a sequential plan to evaluate, and the proper way to evaluate.
Shift linkage-I have assumed that the shift linkage is fine because the shifter can go from park all the way to 1, and the parking pawls engage in the park shifter position, and when shifted to 1 it begins and holds in 1st gear. Also the car will only start in the P or N shifter position. What other ways should I check the linkage?
S1 solenoid-I have seen the previous post in the thread about S1 not functioning, but since the other drive gears seem to be fine at road and highway speeds; I did not see the logic of the S1 being stuck because the drive gears go through the sequence, which involves S1 switching on and off. I will definitely check, but I just did not see how S1 could be the problem.
This week will be one of the last weeks I have to figure this out so I wanted to have a sequential plan to evaluate, and the proper way to evaluate.
11-13-17, 04:26 AM
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Additional S1 logic
I am also trying to understand the logic. When my car shifter is in N, it drives forward in 1st gear and does not upshift. When in D the car advances through all the gears in proper sequence with an increase in speed and drop in rpm after each shift and advances through all the gears. Using the solenoid diagram, that would suggest the S1 solenoid is functioning. Is there some other concept that I am not understanding? I will absolutely check the S1 solenoid, but wanted to understand the logic as well. I do think it is electrical/solenoid related, but cant figure out the logic of a specific solenoid that allows all forward gears in D, but no reverse but hold in R, and 1st gear forward in N.and P.
08-07-18, 02:04 PM
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Help please
Long time admirer, 1st time owner. I recently purchased a '96 LS400 with no reverse, and neutral is also like a forward gear. I've got the same situation as described in this thread. I'm very limited in working with "newer" cars. The last transmission work that I did was swapping one out in my 75 Camaro quite a few years ago. I had a '97 4Runner for 16 years that never needed anything except regular maintenance. So if anybody can please give simple advice that may help I would greatly appreciate it. I live on a hill and can't get it in my driveway (no reverse) so I've not looked at the shift linkage. Not sure where the NSS switch is but I guess I can Google it. Really hoping to get it fixed for a reasonable price, not much money to spare. All forward gears seem to work just great. Thanks and have a great day!
06-08-19, 06:16 AM
#29
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I thought I would continue on this diag since many are having the same issue and nothing further has come thru. I have a 1999 LS400 with the same issue but in my case I have checked the computer and the board looks completely clean, Trans fluid has been changed along with the screen, continuity has been confirmed from the ecu harness to connectors of each solenoid and S1 and S3 are seeing voltage in park and reverse while S2 and S4 are off. It was mentioned on the forum somewhere that low lockup pressure could cause similar symptoms as was s1 and s3 being off. I plan on swapping the SLT solenoid but any other suggestions?
06-09-19, 07:38 AM
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I am facing the same problem on my recently purchased LS 400 2000 model year. Haven't been able to pin point as to where exactly the problem lies. Used a diag scanner but no codes as such.