My red '98 4wd T-100 is still a real "looker", with a modified/SC 5VZFE and the automatic trans. I am the original owner. I do all work myself, unless it's over my head, or I can't endure the down-time. It's my DD.
After about 149K miles, the flex plate cracked and I needed to replace it. I also had a mild torque converter whine, so I sent the converter to IPT for a total rebuild, since they did the VB
and are excellent with transmission work of ALL types.
The shade tree mechanic that did the trans R/R for me was a "friend of a friend" that manages an AAMCO, (but was not ASE/Toyota certified). I was told he was good and meticulous. I was lied to.
Anyway - when the converter came back and the re-install work progressed, I came to regret using this guy at all. When he called me to come get it, I went immediately, even though it became obvious to me that he hadn't even test drove it after the work!
I REFUSE to take it back to him - even though the issues I am now reporting "came to be" only after his "work" on the vehicle was performed.
After I got it back, there were 2 major issues. The minor ones, (such as line pressure cable and shift linkage adjustments) I did myself - and they got the truck into good running shape. BUT...even though the basic peformance of the truck seems great, I get (2) indicators saying otherwise.
On occasion, when I park it - The "A/T P" dash light comes on. Yet it seems that the park pawl is engaged properly - as it should be. I never saw this light before - didn't even know of such. This happens rarely, but it does happen.
Much more often, I also get a MIL (CEL) storing a p1700 code. This happens about 1 time per drive to/from work - which is about 20 miles each way.
I inspected the wiring from the ECM to the #2 speed sensor - and I also replaced the sensor, but it made no difference. I have the Toyota full set of FSM books for the truck and have tried tracing the circuits out repeatedly without reaching the true solution.
I use either my "tuning laptop" or my "Ultragauge" connected to the OBD II port to reset the MIL, but this routine is a real PITA. In FACT - I have NEVER had any such issues with the truck - especially not MIL codes, or dash lights - before I got it back from this trans R/R.
It runs, shifts, & drives fine. But I am out of ideas. I even swallowed ALL pride and took it to my local stealership, (who kept it all day, wrote it up as "NPF", and charged me $105).
Easy answers include either "it's a bad "ECM"" or "intermittent wire harness". Please: save your time and trouble, if either of those are your ideas.
I would rather hear from someone who "KNOWS" - from a similar experience, (since I can "guess" pretty good myself if I wanted to make a game out of it).