Early 700R4 Converter Lockup Method

[getmillican]

I'm asking because I can't find an existing thread that answers this. I have a mostly stock '84 Jimmy. While converting to a TBI, most of the emission equipment, vacuum hoses, switches were removed. I want to be sure the torque converter is locking up correctly. I can’t find anything about the method or wiring on the TCC for this vehicle. Is there a vacuum switch somewhere that should be connected? The wiring exists that is plugged into the transmission, but once the wires entire the harness, I can’t follow them. I would prefer that the transmission operate in the way it was intended to.

 

[DeviousK5]

Your 84 from the factory would already have come with a 700-r4 in it .
Lockup occurs in 3rd(unless by chance womeone eliminated it) and 4th gear. If unsure if it is working get on down the road at about 50mph in 4th gear, lightly apply the brakes (just enough that the lights are on without actually slowing the vehicle down) if you feel that slight change in rpm
it is in fact working. If it is not working the first step is to make sure you have 12v at the connector on the side of trans. See whats goin on with it and post back, it'll be much easier to go from there.

Hope it helps and sorry if i've just told you some sh*t that you already know.

Edit: 12volts at the trans connector, with key on engine off

 

[4X4HIGH]

The early 700R4's used a vacuum switch mounted on the firewall. I don't know much about them but there are others on here that do and i'm sure they will chime in once they see this post.

 

[getmillican]

The transmission is being rebuilt right now, so it won't be until next weekend or the one after before I can try it out. There is so much vacuum stuff under the hoods of these vehicles and I am thinking that I could have removed this switch without noticing the effects. I just want to make sure that this transmission lives a long and healthy life. While it's not the hardest thing, getting them in and out is not a walk in the park and I would rather not do it again any time soon. A 30" long, 3/8" drive extension helped a lot. $12 for a three pack at Northern. 18", 24" & 30" So let me get this straight; we can all agree that all years ('82 and up) all used some kind of vacuum switch to disengage the lockup with low engine vacuum (high engine load) and a brake switch? These two circuits (brake and vacuum switch) are only wired to interupt the signal going into the 4 prong connecter (only three are used)? +, - and signal This would be so much easier with a factory wiring diagram. Does anyone know a source for that?

 

[4X4HIGH]

I'm not sure when it was changed but the later 700R4's DO NOT use the vacuum switch. My 89 trans only uses 1 wire in the 4 square connector but some use 2 or 3 wires depending on which layout GM used in your particular trans. The solenoids in the valve body are different based upon how many wires are used.