ltblue79

So Im finally close to finishing my 5 month long rebuild and Ive run into another problem. This time I cant remember how to hook up the lock-up. I thought I read somewhere that I can just wire in a toggle switch to one of the power wires to lock and lock and ill be good to go. But theres 2 and I cant remember which one and cant find where I read that. So can someone point me in the right direction please or just tell me how they have done it. Thanks!

'75

My trans had a normally closed 4th gear pressure switch so I wired it like this. A normally open switch would have simplified it.
Key off


Driving not in fourth, not locked.


Driving in fourth, tcc locked.

cgc

I have the same transmission with only an external toggle sw. I have a wiring Diag. but not with me. I didn't t use the brake sw or LED as above. If you forget to unlock the car will remind you. If you are interested I will try to post it.

I was running a TH400 with 3.70 and changed to the 200 4r. What a difference. You will love it.

cgc

I found this post by forum member damoroso:

"If you want to delay the lock up of your torque converter you can wire it to a switch so you can choose when it locks up. All you have to do is interupt the 12v supply you have to the lock up selenoid. All you have to do is make sure the black wire is to ground (could be the 4th gear pressure switch, or a direct ground) and the red wire has 12v from the switch. Then you can select when you want to use the lock up. I use it in third depending on traffic, roads, etc., and in 4th again based on the situation. Works for me...."

ltblue79

how do you tell if its an open or closed pressure switch?

77vetteluva

You have to remove the trans pan. The fourth gear pressure switch is installed in the valve body. If you have one with one terminal check for continuity from the terminal to ground. If it has two terminals check for continuity from terminal to terminal. A normally closed switch will read 0 ohms and a normally open will read infinite ohms. When the trans shifts into 4th it will switch.

You need to know this first to determine which way to wire the lock-up circuit.

I have a NO 4th gear pressure switch. I have it wired so that I can:
1. switch it locked full time in any gear.
2. switch it off so that it can't be locked in any gear, or
3. switch it so that it locks only in 4th and when a manifold vacuum switch closes.

The manifold vacuum switch is adjustable so that it closes under the engine conditions you choose.

This is available from TCI transmissions as a kit and includes the pressure switch and schematics. $100
http://www.tciauto.com/tc/200-4r-700...iring-kit.html

spikebot 81

IMO the best lockup design is a 1 wire setup. My 81 was equiped with a th350c lockup system. Currently have a 2004r with full presure valve body. Power runs through a the stock brake pedal switch to the trans connector. Pick up a normally open 4th gear presure switch, install hot wire to one side of switch and other side to tcc lockup soleniod and 2nd wire from soleniod to ground. My system only locks up in 4th gear. When the brake is applied the circut is broken and tcc is disengaged. No need for toggle switch in the car. I only shift to 4th when on the freeway so this system is perfect for my driving style.

77vetteluva

I had a setup like that at first but in some driving conditions the shift to 4th felt like it bogged. The vacuum switch eliminated that. Seldom do I use the toggle switches. Only in unusual driving conditions like rubber neck traffic from 0-55 and back over and over I can shut off the locking circuit. If I am a steady slower speed I can lock it in third if I want. Both situations are not common but it is convenient to have the option.

ltblue79

thanks alot for the help! this is how mine is currently wired up

77vetteluva

ltblue79: Did you ohm out the switch? I don't want to assume you do or don't know. But in your pic the solenoid valve is to the left and the 4th ps is bottom center. Remove the wire before checking continuity because you could get a false reading through another part of the circuit. Do you know how you want to control the lock-up?

ltblue79

I didnt get a chance to ohm it yet. pulling the pan off and snapping a pic was about as much time as I had yesterday. The honey do list was quite long. lol I do have to pull the switch out of the tranny to test it correct? Sorry for so many stupid questions but Ive never done more to a tranny than change fluid and filter. So I really know nothing of what parts are what. I would like to have it wired so that it locks and unlocks by itself in 4th but I want to be able to over ride if necessary.

ltblue79

So I put an ohm meter to it. It kept jumping around a bit but it never read over .5 ohm. I tried it from the terminal to the tranny, terminal to frame, and terminal to the body of the ps. All came up with no more than .5 ohm. So what do I have?

77vetteluva

Technically a switch is 0 or infinite but in your case .5 we will call 0 since there is continuity. I assume you are using a digital meter. That would explain the jumping around. So what the results say is that you have a normally closed switch that will open in 4th gear. This type of switch requires at least a relay (like in '75's schematic) or a computer. Ultimately we want to close a the circuit that operates the solenoid valve. A 4th gear PS that closes in 4th make the circuit simpler. Either way, IMO you should replace the NC PS with a NO PS switch, install an over ride switch to shut off LTC circuit, and what ever other control switches you want to make the TC-lock more driver friendly.

A torque converter is the link between your engine and transmission like a clutch. At lower rpms it has a lot of slip. When the rpms go up the slip decreases but not 100%. When the converter locks the slip is gone completely as if a clutch were fully engaged. Imagine in a standard trans shifting gears or braking without using the clutch. That is why you may want a vacuum switch and/or a brake pedal switch.

ltblue79

ya it is a digital meter. so I will try and get a open ps.

ltblue79

So 130 miles later I managed to find a open switch. Now my question is. what is the best way to wire it up?

'75

If you get a brake light switch for an 82 it will have a set of contacts that are normally closed. Mine is made in usa by Standard part no SLS66. Just run power from the accessory tap on the fuse panel to the new brake light switch, then to a shut off switch if you wish, then to the tcc solenoid. The other lead from the tcc solenoid can go to the new n.o. pressure switch. If the new no pressure switch has 2 terminals, just ground the 2nd one to the trans.

ltblue79

If I take the red wire from the solenoid valve and hook it to one of the 2 posts on my new op ps and then run the other remaining wire from the ps out of the tranny to a positive wire with a toggle switch that should work correct?

77vetteluva

Assuming the other SV wire runs to ground, then yes. Your torque converter would lock whenever the trans shift into 4th. IMO the driveability is more comfortable with other things controlling lock up as well as the 4th PS. Here is the schematic of mine. One of many ways it can be done. Others may have some suggestions that work well also.
-Rick

ltblue79

Thanks 77vetteluva! I had found this on the turbo buick site.

And that is what I did. Pretty much same as yours except for the vacuum switch which I can add later. Once I find a suitable one from a junkyard.