2007 Tundra Tranny slipping

Good day everyone. Have a question and hopes that someone had the same experience and solved the problem.

I have a 2007 Toyota Tundra 4x4 with 5.7L iForce, 6 speed auto. I just bought the truck and got it on the road as a daily driver. I have noticed it is shifting really weird.
For example, sometimes when I put it in drive, the D doesn’t light up on the dash and when that happens, the low4 light on the dash flashes. Once I play with the shifter until the d lights up, then, everything seems fine.
But what happens all the time is when driving, the truck shifts gears very late at high revs if I give it to much gas. If I give it very little gas, it seems to shift fine. Also when driving, if I give it some extra gas pedal, it seems to go in low gear way to fast and high revs like I am going street racing. Lol.

Any advice would be amazing. Thanks a million in advanced.

 

How many miles are on the truck? Have you service the transmission?

 

Has the fluid ever been changed? I would start with that ....you'd be amazed at the difference fresh, good fluid can make.

 

Truck has about 175,000 miles on it. And the truck had papers of a tranny flush at the Toyota dealership 3 years ago.

 

I'd do a drain & fill (not a flush), and maybe throw a bottle of Sea Foam in it.

 

By doing a drain and fill, do it yourself so you know it has been done. This is definitely one of those services that is frequently billed but not actually done.

 

I would side with drain and fill... my transmission has been acting funny, with no real regular maintenance, until now... when I have started thw draining and filling maintenance...

 

I would check the slack on the PNRD switch an see if its needs adjustment. Since its not registering the D light unless the shifters played with. Also doing a test and inspection of its functions would help shore up any doubts an go down the line from there.

a half unrelated issue I had happen was when my led tail lights were going out it pop a fuse stopping the indicator from working witch if I recall gave some issues with driving.

also as always make sure battery terminals are clean and tight.

could be a wiring issue or ECM give me a moment to dump info in 2nd message.

 

These three areas above are all related they are controlled by the ECM but the ECM also needs info from them.



this process above will help rule out worn clutch's or low line pressure that would be a mechanical issue for cause of slipping






all these ones above are info and testing on the Park/Neutral switch. Witch could cause the known issue with the D indicator light not coming on unless the shifters fiddled with.
the 4lo light flashing is a warning for a issue with this said circuit witch house's a lot things besides PN switch.




all of the above is ECM and ECM testing witch can also be a cause for this issue.

I tired my best off the info given to gather this info with out dumping hundreds of pages. a few things can help me provide more accurate info like witch version of the 5.7L and console shift or column shift. thanks
hope this information helps and allows you to get to the bottom of this.