converter randomly unlocking

96 350 4x4 auto. bone stock
three times today i was going down the highway, round 70 on a slight uphill. in the rain, lights on. not touching any other controls the converter unlocks for a few secs and re locks. i had an issue in the past when i put in led tails that i would put the turn signal on and it would unlock but i thought i solved that. i dont know if it would be related but occasionally the truck will rev up to about 900 rpms then jerk forward.
any insight would be appreciated
thanks guys

bbump it did it again tonight. anybody?

I seem to remember someone having that issue and it was a fubar trailer connector receptical. I only vaugely recall that though.

i could have a look, i had an issue with led tail lights and the turn signal unlocking ti but i thought i had that straightened out. maybe its related?

thats weird having to do with electricals.. overdrive flashing?

nope. nothing. its just a momentary thing. unlock then re lock. maybe a second or two tops

bump. i checked all the connections and they look good. im going to go ahead and change the fliud since ive never done it. and for all i know its the original atf. so im planning on doing that tomorrow or tuesday whenever i get time. and tips or hints?
also my tc should have a drain plug right?
thanks guys!

I think yours will have the drain plug. I think the convertor lock wire is purple with a yellow tracer if you want to monitor it to see if the PCM is commanding the unlock.

Another thought is your brake pedal return spring weak causing the brake lights to come on once in a while.

thanks!
how would i do that? tap in an led?

Yes the PCM supplies the ground on that wire to lock the convertor.

so i would need a power wire to the light then ground it to the wire to the pcm?
sounds like a good addition to the project

i seem to have dat same issue it started its done it before but i would mess with the lever and get it working but now it seem like its starts out in 3rd or just slips alot in 1st. when i shift manualy its fine but the converter aint locking. i had trailer brake issues before any suggestions???

sounds to me you have bigger issues than i do. might want to start saving for a rebuild

What I have for set up is a temp one I can put in or take out of the the truck. I it plugs into the cigarette lighter plug for power and the other end connects to the wire I mention. I have used it in the past when we were tuning.

i like that idea but i think im going to do a permanent, or atleast semi permanent one. the fluid change was a success the pan didnt have any sludge or build up. the magnet had just a light coating of very fine particles. but the fluid was pretty dark. almost brown.

it has yet to unlock for no unknown reason. but on acceleration it will partially lock, unlock then lock. but the pcm is telling it to do that. any reason for that?

Is your partial lock, un lock, re lock on the 3-4 shift? It will lock at the top of 3rd, then unlock as it shifts to 4th, then relock as it is in 4th.

I agree with the PCM might command an unlock on certain shifts.

May not have anything to do with this particular issue, but about 1 month before my trans completely blew, i was having this issue while cruising down the highway at 75mph or so. It would be fine, then unlock, then lock, then unlock. It was kind of random too.

on acceleration i will be in 3rd around 35 it will partially lock, then unlock. then at 40-43 it will lock then shift into 4th as usual. this is usually on a moderately hard acceleration like getting on the highway 1/2 to 3/4 throttle

it has not randomly unlocked on the highway since the fluid change though