AT Transmission Problems

Hey transmission gurus!

2001 SR5 4.7L 4x4.

Anyone have any idea why my truck only moves forward in all gears. I can put it into any gear and rev up to about 1800 RPMs and it will move forward. Park takes about 200 RPMs. I just put a new torque converter in it and cleaned all the old metal and needle bearings I found in the oil pan and valve body. Quick rundown of the problem and what I have done.

It started while I was at a red light. I gave it some gas to go and it died. Put it in park, started back up, put in gear and it died. It would idle just fine in P and N, but die when I put it in any other gear unless I gave it a lot of gas. And, the AT Oil Temp light would come on. Then it would drive just fine until I slowed down. So did some research and most things led me to the TC. First checked the solenoid and it actuated just fine. So I replaced the torque converter. Once that was done. Started it up, put it in gear and it did not die. That's when it started with only going forward in any gear. At this point it would move forward without applying any gas.

Pulled the valve body back out and cleaned it again. Only found metal in the Lockup Valve. Replaced the separator gaskets. Installed it back and now it still only moves forward, but only when I get it up to about 1800 RPMs. I am not getting any codes. Any ideas would be greatly appreciated.

I think all the metal and needle bearings are from a previous TC replacement. The one I removed was fine. I know this because I cut it in half to see. All bearings were intact. I think someone replaced it and didn't clean out all the old metal.

 

With that much debris in your transmission it needs to be rebuilt and you need to replace the radiator and transmission cooler. There is probably debris in those also and not a good way to clean them and not worth the chance of contaminating a new transmission.

 

BCRStealth

What you are describing is exactly what is happening to my 03 tundra 4x2, but the circumstances are different. My transmission was shifting through all gears alright, but was slipping a bit from 1st-2nd, otherwise was working fine. I found the transmission output seal was faulty and leaking fluid all over the underside of the truck, so i replaced it and pulled the pan to do a drain/fill and replace filter. No metal in the pan but fluid was a little dirty so i removed the valve body to clean it and clean the solenoids just to make sure they weren't the cause of the slip. The gasket on the valve body must have been original with 330,000 miles and it just disintegrated, so i ordered new gaskets and disassembled and cleaned the entire valve body. I put it all back together as dissassembled, refilled with 4-5 quarts of fluid, started the truck up and I realized it had started as if it was in drive with resistance on the motor. The tach jumps on start but falls immediately instead of gradually and the truck jerks forward slightly. When shifting to reverse, nothing happens. It stays in drive. Neutral does the same thing, just stays moving forward.

I decided to drive it a bit to see if it would still shift. It seems to upshift just fine, much better in fact than before, but violently downshifts and feels like the transmission is trying to brake the vehicle hard. I decided I must have broken something in the valve body or at least reassembled it incorrectly, so I went to a junkyard and pulled another valve body from a 01 sequoia with the same casting number 8938. I installed it straight into the transmission, refilled pan, and started up with no change in the issue. It still starts like its in drive and will only move forward with no reverse or neutral. I know it has to be an issue with the valve body, or something with the sensors or ECU as the transmission itself functioned before the cleaning and valve body removal. I have searched the internet looking if anyone else has experienced these symptoms before and have only come across your post and another on answers.com where someone had their tranny rebuilt and experienced the same issues even after it was taken back apart, reinspected with no issues, and reassembled with no resolution. This is why I'm thinking it could be something electrical.

 

Just an update:

This probably won't help anything but who knows. I took the transmission pan off the truck again just to have a look and I realized that I had completely forgotten to connect the shift link pin on the linkage in the groove in the back of the manual valve or shift valve. The valve was sitting in front of the link pin, so when I was shifting gears, only the shift link was moving and the valve was doing nothing. Took off the VB, ran the manual valve out a bit and set the link pin between the two little grooves on the back of the valve. I put it all back together, started up the truck, and all gears are working again!

I noticed after I posted my first reply that you said you have to rev to 1800 rpms to get it to do anything, so our situations are quite different but I figured its possible my post might help someone

 

@SPSHE Nice! I breathed a sigh of relief for you..

 

SPSHE,
Thank you so much for your write up as that fixed my problem with no reverse and no neutral. Fantastic!