Update: Shifting problem (2 Viewers)

[Malleus]

2000 LX470 (295k miles) with a shifting problem. First gear winds up to the redline, unless you let off the gas, then it shifts from second to O/D normally. Before I go through the entire xmsn troubleshooting list, I'd appreciate any thoughts from anyone who has had this problem and solved it.

 

[smartparts]

2004 Transmission Issues

So driving home on the highway at about 65 mph and all of a sudden it started to decelerate and the rpms went up, as if the transmission was in neutral. Coasted to the shoulder immediately and put it in park. VSC lights and CEL were illuminated. Grabbed my scanner and got codes P0986, P0974...

forum.ih8mud.com

Currently working through it. Still havent figured it out. What codes do you have?

 

[Randokuruza04]

Yes, I got a full transmission flush/ change on one of mine and its been fine since

 

[Malleus]

2004 Transmission Issues

So driving home on the highway at about 65 mph and all of a sudden it started to decelerate and the rpms went up, as if the transmission was in neutral. Coasted to the shoulder immediately and put it in park. VSC lights and CEL were illuminated. Grabbed my scanner and got codes P0986, P0974...

forum.ih8mud.com

Currently working through it. Still havent figured it out. What codes do you have?

No codes

 

[gatormark91]

The lockup torque converter clutch gets dirty from old trans fluid with expired cleaners and shear additives. Odd behavior like this is usually seen at about 35-40 mph. Do a FULL fluid exchange (NOT a power flush, not 3-4 quart pan drain/fill) and I'd expect that behavior to go away in less than a week of driving. But before you do anything make sure the fluid is filled to the proper level.

Not guaranteeing this is the problem, but it's the most common and likely culprit.

 

[ramangain]

Agree with above ...

1. Ensure fluid level is at the correct level, measuring the correct way.
2. Do a search for user 2001LC and his long thread that has multiple pages. One of the pages has step by step instructions for doing a full tranny fluid exchange for the 4spd trannys. I found that the cheapest source for the Mobil1 ATF was Walmart online. Tools needed are basic and not specialty, and except the long wait for the tranny fluid to drain from the pan, should take a couple of hours.

 

[AlpineAccess]

An exchange can be done quickly, but if your fluid is truly bad enough to cause torque converter to lock up like this you're going to want to drop the pan and ensure the pickup screen is clean as well.

 

[gatormark91]

An exchange can be done quickly, but if your fluid is truly bad enough to cause torque converter to lock up like this you're going to want to drop the pan and ensure the pickup screen is clean as well.

I dropped my pan and cleaned it out at the same time I did the flush.

 

[AlpineAccess]

I dropped my pan and cleaned it out at the same time I did the flush.

This was directed at OP. But looking back at your post now I see you didn't mention it so that's good info.

 

[nukegoat]

2000 LX470 (295k miles) with a shifting problem. First gear winds up to the redline, unless you let off the gas, then it shifts from second to O/D normally. Before I go through the entire xmsn troubleshooting list, I'd appreciate any thoughts from anyone who has had this problem and solved it.

Sounds like pressure sensors or solenoids TBH

 

[Malleus]

Sounds like pressure sensors or solenoids TBH

That was my initial thought too. Not ever having opened one of these, I thought it would be worth asking for second (or more) opinions.

 

[smartparts]

Sounds like pressure sensors or solenoids TBH

Wouldn't this throw a code?

 

[Malleus]

Wouldn't this throw a code?

I guess that depends on what the sensor saw and what range is slipped in. I would think so, but it's possible it's within tolerance and just outside of operating range at the same time. The only way to know for sure is to open the case and check the signal on the sensor. I was hoping that would be a last resort measure.

 

[ramangain]

Was this an issue before the last tranny fluid service?

 

[Malleus]

Just bought the truck, so that's a big unkown...

 

[Malleus]

Agree with above ...

1. Ensure fluid level is at the correct level, measuring the correct way.
2. Do a search for user 2001LC and his long thread that has multiple pages. One of the pages has step by step instructions for doing a full tranny fluid exchange for the 4spd trannys. I found that the cheapest source for the Mobil1 ATF was Walmart online. Tools needed are basic and not specialty, and except the long wait for the tranny fluid to drain from the pan, should take a couple of hours.

Found him, and his many threads. That was the best use of three hours of my life recently. Many thanks to you and to @2001LC.

 

[smartparts]

Any update on yours?

 

[Malleus]

Still on the back burner; trying to finish a garage expansion this weekend. It's on the plan for next week.

 

[Malleus]

Completed the flush yesterday. It wasn't black, but it wasn't far off. The last quart or two was really nasty, with obvious suspended particulates. I let the pan drain for a full week (weather related delays here) and got 5 full quarts out, which made me happy; that was five quarts I didn't mix the new ATF with. One odd thing: when the 12th quart went in, the dipstick showed about 3/4 of a quart high, when hot. I drained a full quart out today, and now the dipstick shows a full quart low when hot. Road test made both before and after draining a quart from the refill. No difference in the results between the two road tests.

Shifting, when it happens, is as good as I remember it being when my (previous) 100 was new. The problem is now the first and second gears seem to be slipping under load at about 3000 rpm, while the transmission is climbing through the gears from a stop, or slow roll. The failure only happens at 3000 rpm and seems like the rear wheels are locking, or dragging at least. This is definitely not an axle problem, it's related to the transmission shifting.

If I accelerate slowly, (like driving Miss Daisy slowly) and hold the acceleration to near zero at the end of the first and second gear shift points, it does shift, at about 2600 rpm. When I use the 2nd start bypass function, I get the same result with 2nd gear as with 1st.

Next to try is the shift solenoids. Since I'll have it open, I'm replacing them all, even though the drive and overdrive gears don't seem to be affected. At least, not yet.

I fully expect to have to rebuild this over the winter, so I'm on the hunt for a donor transmission I can use for the 2000 LX470 and my two 1995 80s. These will be down the road projects, maybe 2022, but I'd like to have a spare installed while I'm working on the OEM unit.

 

[looking4lc]

Completed the flush yesterday. It wasn't black, but it wasn't far off. The last quart or two was really nasty, with obvious suspended particulates. I let the pan drain for a full week (weather related delays here) and got 5 full quarts out, which made me happy; that was five quarts I didn't mix the new ATF with. One odd thing: when the 12th quart went in, the dipstick showed about 3/4 of a quart high, when hot. I drained a full quart out today, and now the dipstick shows a full quart low when hot. Road test made both before and after draining a quart from the refill. No difference in the results between the two road tests.

Shifting, when it happens, is as good as I remember it being when my (previous) 100 was new. The problem is now the first and second gears seem to be slipping under load at about 3000 rpm, while the transmission is climbing through the gears from a stop, or slow roll. The failure only happens at 3000 rpm and seems like the rear wheels are locking, or dragging at least. This is definitely not an axle problem, it's related to the transmission shifting.

If I accelerate slowly, (like driving Miss Daisy slowly) and hold the acceleration to near zero at the end of the first and second gear shift points, it does shift, at about 2600 rpm. When I use the 2nd start bypass function, I get the same result with 2nd gear as with 1st.

Next to try is the shift solenoids. Since I'll have it open, I'm replacing them all, even though the drive and overdrive gears don't seem to be affected. At least, not yet.

I fully expect to have to rebuild this over the winter, so I'm on the hunt for a donor transmission I can use for the 2000 LX470 and my two 1995 80s. These will be down the road projects, maybe 2022, but I'd like to have a spare installed while I'm working on the OEM unit.

I suggest you to clean all solenoids ( 7 of them I believe) with ONLY electrical cleaner then slow air pressure before you replace them, btw they are not cheap, I had success story with cleaning them from gunks.