07 5.7L Tundra Transmission Woes

Afternoon all,

Well, welcome to backyard maintenance. Several weeks ago, a Safety Neutral Switch (SNS) code ended up being thrown up on the dash. Being the proactive guy I am, I ordered a new switch and started a host of problems that are still haunting me.

First off, the shift linkage on the 07 Tundra passes through the entire transmission, engaging each gear from the shifter. On the end of that rod, past the SNS, lives a threaded bolt. With very little pressure, it sheared off with about 1/4 inch to spare. The SNS was just as much as a nightmare, with the aluminum guts of the switch being seized to the transmission shaft, having to be cut off with a sawzul, as a disc grinder and the aluminum would bind up. After replacing the SNS, connecting everything back up and starting the truck, the codes remained.

Downloading the electrical diagram, I started chasing wires. Thinking it was a broken connection, I was still getting 12v at the switch when it was in Park. It wasn't until I had nearly torn the entire truck apart chasing wires did I realize the SNS has two power sources, one in Accessory and one when the truck is on. Low and behold, the 10 amp BK/UP LP was burnt out. Replaced, and running! Sort of.

Now, what to do about the snapped bolt. A mechanic buddy suggested JB Weld, make sure everything is working and if it holds, beauty. If not, weld it, since pulling the entire transmission to replace the shift rod wasn't going to be an easy option. JB weld, 24 hours, adjust the linkage, actually running!

Now for a test drive.

Threw the dogs and the kid in the truck and headed for the river, but as soon as we left the driveway, the transmission started to lag. Intermittent power, enough to power partially up hills, partial engagement, etc. I thought it has something to do with the JB weld, which was partially right. Got to the river, less than 10 mins, and things weren't progressing well.

When we got to the river things really started acting up. The linkage was sloppy and wasn't getting into Park or Drive, so I had to manually pop it into park from under the truck. Same for Drive when we wanted to leave. Found out later that the JB weld, between the transmission heat and the exhaust, melted (softened) to the point the bracket would wiggle back and forth, so it wouldn't fully engage either Park or Drive.

Under the truck, pushed into Drive, started out of the parking lot, and the transmission issues started getting worse. Little to no power, even though the truck would seem to engage, it wouldn't gain any speed. Codes started getting thrown on the dash, so I parked and got a tow back to the house in Neutral.

Under the truck again, thinking that it was just the SNS linkage giving me grief, welded it up for good, started the truck, still no power in Drive.

Checked the transmission fluid, very dirty and burnt smelling. Time for a complete transfer. 12 + Liters later, fluid check at temp and... still nothing.

Started looking at the codes again. P2714 Pressure Control Solenoid "D" Performance Or Stuck Off and P0751 Shift Solenoid "A" Performance Or Stuck Off. Check the forums: filter, bad oil, bad solenoid, or transmission issues (along with a host of others).

Drop the pan (snap 6 bolts as well), some beyond small chunks and shavings in the pan and on the magnet. Enough that they feel like small sand in between your fingers. While I was there, I pulled all the solenoids and checked power/continuity. All were functioning and had good resistance.

Thoughts? Filter could be replaced, but with the shavings/grit, something is probably up in the transmission. What get's me is that it was functioning 100% fine prior to the SNS/fuse issue. Only thing that has really changed was the ground wire I replaced from the transmission to the frame. Any particular reason it would start acting up all of a sudden now? Am I missing something or is this just bad timing and not related to the SNS at all. I have a hard time believing that the transmission could be sitting for a month while I was working on the SNS and all of a sudden it dies....

Advice would be gratefully accepted at this point.

Thank you,
Wolff

 

There are a few. Still trying to diagnose if it's truly the transmission or something else. Went through the pan and cleaned out the filings. They aren't what I would expect, they are metal but black and chucky. I would expect that after cleaning they would be bright metal? Rest of the filings are what you would expect from a not well maintained transmission...