Lock up converter question

[Syleng1]

vehicle: 1986 Dodge short passenger Van- carburetor 318/904 8-1/4 rear.
All stock. Factory ignition is that lean burn looking, Over priced, prone to failure ignition computer.

Build up: I’m calling it a A904 but it is actually called a a998 I believe. It appears to be lock up converter and has a single black plug on the rear of the driver’s side pan lip facing forward.
I don’t have a PK# yet. It is very oily and dirty and needs a power wash.

I know little about this converter if it actually is a lock up. I’ve driven this van only a few times around the block due to lack of registration.
Question: from what I’ve read- it is a hydraulically controlled lock up. BUT if you apply 12vdc to the solenoid, it opens the solenoid and dumps the pressure to the converter clutch. Main reason would be for towing or heavy load. Is this correct?
Is this how the 80’s style lock ups work?

My goal is to swap out the computer with a 4/5 pin ecu like we all know and love (and distributor) but because that computer controls the converter - I need a way to shut down the lock up when hauling or towing. It seems simple enough, right?
Thanks for the help-
Syleng1

 

[Darter6]

I have no correct answer for you.
Try looking up Mopar Action Magazine archives on line.
I remember several articles about locking converters, how they work and how to disable them.

 

[Syleng1]

So I checked and the trans number is PK 4348715. 318 A999 “PTU”
No idea what that means.

 

[Syleng1]

I have no correct answer for you.
Try looking up Mopar Action Magazine archives on line.
I remember several articles about locking converters, how they work and how to disable them.

Thanks but I’m not looking how to disable, but to understand if I know how they work and can keep it (lock up) without computer control. Most hot rod type info is how to disable the lock up which the more I learn is a horrible idea for a plain Jane passenger type vehicle.

 

[Professor Fate]

I forget where it is- it's been a while; but either on the inside of the glove box door or on the driver's door jamb there will be a sticker listing the powertrain numbers, and will show what trans it is. Around that time they changed the designation from A999 to 32RH, so it could have either one listed.
The lockup can be controlled with just a toggle switch supplying 12v to the connector; use an illuminated switch so you know if the lockup is active or not at a glance.

 

[rbkt65]

Ptu is part throttle unlock. That means if you accel a little, it will unlock the lockup part. Might try a toggle switch but keep in mind. U will have to remember to unlock it when coming to a stop.

 

[Professor Fate]

You've got to remember that the trans hydraulically engages/disengages the lockup- the connector and solenoid is only there to defeat the lockup for towing/hauling, unlike later OD transmissions that utilize full computer control.

 

[Syleng1]

You've got to remember that the trans hydraulically engages/disengages the lockup- the connector and solenoid is only there to defeat the lockup for towing/hauling, unlike later OD transmissions that utilize full computer control.

Thank you Professor. That was what I was looking for. Just confirming that the solenoid dumps converter pressure for hauling/ towing.
Syleng1