Torque converter locks up at 30 MPH peed sensor? TPS?
 

So I've got a built trans with Billet torque converter. The torque converter is locking up at 30 MPH, I replaced the lock up solenoid but its still doing. Could it be like a Speed sensor? or the TPS? Should I look into doing a torque converter lock up switch or a POT?

I would do the switch, and don't just tap into the lockup wire, cut it. That way it will lock when you want, and can't when you don't want.

I drove it quite a bit on Monday and after a while it started locking then when you ease off the gas a hair it would unlock and then when you get back into the gas it would lock again.

That's the normal function, one of the main reasons people install lockup switches is for engine braking because Dodge didn't think it was necessary... in spite of the circa 1989 Plymouth Voyager braking system they put in it.
It's been so many years since I've let the PCM control anything that I forget what the normal speed was for the PCM to lockup in 3rd and OD, but I do know that when you build a trans and start cranking up line pressure/etc it will affect it, because the PCM is stupid and doesn't know that things have changed.

i think I’m going to bypass the tps with a POT and also put in a lock up switch wired up like a high beam switch

Mine is wired through a floor mounted dimmer switch, if you're going to use it a lot it's the only way to go.

my truck is my second vehicle. It’s used pretty much exclusively for towing my dragbike trailer across the southeast for racing so I’m figuring mount it like a dimmer switch and be done with it

so just to clarify, basically I just need to cut the wire going to the lock up clutch, wire it to the dimmer switch and wire the other dimmer terminal to ground and just tape off the end of the wire coming out of the pcm?

IIRC, it was essentially adding a switch to the wire. I believe there was three poles on the switch, an in, an out, and a ground. I could be wrong though, because I also had a jumper through a rocker switch that allowed me to bring the PCM back in as Dodge intended if somebody was going to be driving who isn't familiar with it. I really don't remember how I did that. The whole thing was also on a Hobb switch that operated off drive pressure from the trans, so it would automatically unlock under a certain speed so nothing grenades in a panic stop. It all seem to be a good idea at the time, now it just seems too complicated to remember. But I'm pretty sure I cut the wire at the PCM, ran an extension inside to the dimmer switch, back up to the other side of the cut wire, a short leg off the switch to ground it in the cab somewhere, and if I had it to do again I wouldn't bother with all the rest.

I don’t have my proper drafting equipment so verify this with me please,
https://cimg4.ibsrv.net/gimg/www.die...688ac5fa8a.jpg

Upon pulling up the carpet and looking at the switch again (which contrary to my memory, is a two pole) yes, that all looks accurate. I suspect the reason I thought that I used both ends of the cut wire at the PCM is because of the "average Joe" toggle, but I'm not ripping apart the harness to confirm that. It's the only thing that makes sense.

Well, I knocked it out today, I wired in an average joe switch, wired a dimmer switch to ground and also wired in a red LED to the transmission leg on the dimmer to signal when the torque converter is locked up

How did the LED work out? I was going to do that, but somebody told me it wouldn't work how I expected. Namely, that the light would only be on when it was unlocked, not when it was locked. I think. I don't remember, it was a long time ago and I never tried it. Now I sort of wish I had, since the OD off light in my cluster stopped working (not the bulb). Oh well. I went from driving the truck over a thousand miles a week to less than a thousand a year, so I can't really be troubled to care too much about the little things anymore...

I’m testing it out today, so I’ll let you know. I just spliced the LED into the same leg as the wire going to the torque converter. The way I understand it, when it’s not grounded the torque converter Is unlocked but when you hit the dimmer and apply a ground it locks so when it applies that ground it also applies a ground to my LED allowing it to light

tested the truck out yesterday by taking my boat to the lake. I regret not doing this lockup switch sooner! The LED works great and illuminates when the TC is locked and goes off when it’s unlocked.

Nice! You have motivated me to actually do something with this truck again. I'm probably going to wish I'd done the LED years ago.

It was very nice to have a little reminder. I had to lock it down when a car stopped in front of me and that LED helped remind me to unlock it. Next step is the TPS delete with POT. Thanks for all the help Jbear!

Glad it worked out