So I just swapped my trans in my 92 ls400,after starting and letting it warm up and getting fluid level right it would slam into drive but no reverse, after cycling through the range of gears a few times nothing. If I shut the car off and restart will go into drive and a real slippy reverse.

what I’m thinking is that the new transmission (junkyard) had moisture etc. on the inside and by refilling it and moving again a bunch of debris is in the filter starving the transmission of fluid.

Before I go about getting another transmission or rebuilding this one, I’m thinking change the filter and flush transmission and go from there.

any input would be helpful

I did swap torque converters so it is using the original converter not junkyard, dropped pan there was a little moisture so I sprayed down with brake cleaner, replaced filter and gasket and refilled

 

You can try a flush and filter change but I doubt it will do anything. Just do the flush first and then change the filter.

Why did you swap in a different transmission? If you're going the rebuild route, you might be better off rebuilding the original. Basic kits (steels, frictions, seals and bands) are relatively affordable. I would add solenoids, wiring harness, bushings and the pump as well.

Finding a local rebuilder would be the most trouble free route.

 

I swapped transmission because no reverse. Previous owner replaced all the solenoids and flushed and still no reverse. The car came with a extra transmission from a junkyard with 124k on it my car is at 291k.

I swapped torque converters because there was surface rust on the junkyard converter the made line up with flex plate harder than need to be so I swapped out.

I intended on taking pics but I was covered in burnt atf and didn’t want to get on my phone.

 

Does the car want to move forward very slowly even when you set the AT neutral?
If so, I can give you an idea to find the root cause of your problem.

 

Honestly not sure, it will be a few days before I go back to the car. I am retired military and I rented a lift on the base (where the car currently is) definitely worth the 54$ daily rental,but they are closed Sunday and Monday so Wednesday or Thursday.

The new trans had very little shavings on the magnets, fluid wasn’t the best but not super burnt.
I did break the connector to the output speed sensor but I got a new one soldered and heat shrink. When I pulled the converter was clean and dry behind no leaks or anything.I put my torque converter on too be safe the junkyard one had some lite surface rust from siting in the garage and I know that the fluid was good in mine.Only things that gave resistance was a broken exhaust stud and having to tweak the dipstick tube on the as it was 1/4in off no kinks in the bend.

After I pushed it out the stall into the parking lot I decided to start it up and try.I got drive, moved 6in then put in reverse and I could hear it engage but it was like I had a clutch right on the engagement point would barely move.

This is my first automatic car all other have been manual but my hips are destroyed and clutches are no longer enjoyable so I’m not that educated or experienced it’s voodoo magic as far as I know

 

What I worry about is that the solenoid S1 is not driven caused by the failed solenoid driver or the failed harness/connector.

See the table below which explains the relationship between solenoids and gears. When S1 is not driven and it is always off, the reverse gear is not engaged and the car wants to move forward as if 4th gear is selected.

 

The old transmission had the solenoids replaced and I still have it so if I need some I got that covered.

As for the driver, I’m assuming it’s an internal part of the ecu? Would I be able to test with a multimeter?like unplugging one of the sensors and checking at the plug or at the ecu? I am almost certain that the ecu could use a rebuild but I have never looked, perhaps I’ll pull it open and see. I will take pictures this time as I shouldn’t be covered i crap lol

I also found a few leaks, the valve covers both but drivers side is the worst,and the boot on the passenger side of the p/s rack has a tear and fluid inside so I need to either rebuild or replace it but I want to do pump at the same time as I can verify it seaping not quite leaking yet out of reservoir.

I haven’t had the car long but want to get it right, the previous owner/owners were not the kindest to it but the potential is there and I’ve wanted one since I was 13yrs old so I’m not scared of a little work but there is a lot I don’t know especially when it comes to the transmission.

Again thanks for the reply I feel like I got a 50/50 chance that I won’t have to pull the transmission and figure out a replacement or rebuild

 

Yes, AT's solenoid drivers are all inside of the ECU. The solenoid S1 is driven via the pin number 4 of the 8 pin connector below. It is located at the side of the AT unit. The confirmation of the driver is simply done hooking up a clamp DC meter to the pin 4 line. The current should be around 0.85A when you shift to the reverse position.

 

Didn’t get to do much as the weather has been terrible every time I get time so I pulled the ecu and am looking to get the capacitors replaced as well as a general check of the ecu.

I did talk to the guy who runs the facility where my car is at and was telling him the tests I want to do (checking voltage at connector) on the transmission. I am not allowed to have anyone in the car on the lift.
They are drive-on lifts, not the swing arm or 4 point lifts.

So my question is can I check voltage at the connector with keys turned to the on position but the engine not running? I’ll have the wheels blocked so it can’t move of course

 

I am talking to ls cowboy about my ecu and shared where I am at, my question is he has a good ecu for my year, should I have him build on of those seeing as my driver may be the issue? I would hate to have the caps replaced just to have a bad driver. I can upload the pictures I sent him( nothing obvious regarding damage), all original from 1992 and is the correct part #.

 

So I replaced the ecu with one refurbished by ls cowboy and the car worked perfectly while on a short test drive. Went from drive to reverse at least 10x no issues.

I shut the car off for approx 10min too lock my other car and grab my phone and drive it home.
this time when I started it did nothing, I mean nothing in any gear.no unusual noises, nothing

So my logic is as fallows:
since I have two transmissions I’m going to find a shop to do a rebuild on my original transmission and pretty much abandon the one in the car now.I think the new fluid killed it .

Makes me wonder if I would’ve done the ecu first I might have dodged all this but it is what it is at this point.

Thanks everyone who contributed as I 100% believe the ecu was the root cause and I just made new problems for my self, Multiple lessons learned