700r4 lockup question

[silversnail86]

Ok, I have an 86 c10 that originally had a 305 "ecu" motor. It now has a carbed 350 seems to drive ok but this is only second automagic I've ever owned.
I was cleaning up some wiring today and found a little vacuum controlled box that has 2 vacuum ports and 2 wires 1 blue and 1 yellow. yellow is coming up from the trans lockup dealybob on the back drivers side of the trans above the pan. I guess my question is How would I know if someone went with a non lockup convertor or installed a lockup kit or if it's just plain not hooked up? There are also 2 different electronic/vacuum deals on the firewall that are not hooked up they each have only one vacuum line. Thanks for any help!!

[silversnail86]

After another hour of research i found out that what i am looking at are 1 firewall mounted "tip in" switch for the old electronic carb or whatever it was, 1 firewall mounted switch is part of the lockup control this is next to the brake booster, and the dual vacuum switch I am guessing is also carb stuff cuz the wires go together with the tip in switch. Only thing i need to know now is whether or not to give the lock up swith full manifold vacuum or not my guess is yes???

[crazeetxn]

Don't quote me, but lockups on the 700r4 are electronically controlled. There's not a vacuum modulator on them (least not on mine). With the wiring, there's usually only one wire that goes to the tranny with 12v that will shut off when you apply the brake so it doesn't stall out on you.

[silversnail86]

Well the lt. blue wire that comes out of the brakes for the lockup goes into this vacuum switch. From what I understand it's there for low vacuum shut off for the lockup. So when you give it some gas (not enough for a downshift but enough to drop vacuum) it unlocks.

[silversnail86]

OK so I hooked up a vacuum line to that vacuum switch and now my convertor unlocks when vac drops but I now realize that my torque convertor has been locked the entire time I've owned it plus a long time before that. Would a locked convertor hurt things or itself? The brake switch was working.

[gchemist]

You can ditch the ESC box. Change the distributor to a non ESC. Or bypass it. Read this: http://www.73-87.com/7387garage/drivetrain/escrepl.htm

I removed the entire ESC system when install my ZZ4.

[silversnail86]

The esc is in the truck but all disconnected. But that has nothing to do with anything I'm talking about.

[crazeetxn]

Have you checked out www.bowtieoverdrives.com ? They have alot of good info on
700R4s.

[silversnail86]

They do have alot of great info but not what I'm looking for. Now the issue I am having is that the tcc is locked in all gears until I either hit the brakes or give it a fair amount of throttle so I am just going to wire a switch to my brake/tc wire and turn it on and off that way... I think

[crazeetxn]

Look at their lockup kits. Simple install or replace and it comes with everything you need to wire it up right. Even have a toggle option for towing.

[silversnail86]

My truck came with a 700r4 so it has all that stuff right o[U]t of the factory and if I could figure out why the convertor is locked until I force it off with the brake or low vacuum I would use all that factory stuff. All I have to do is place a switch in the already existing wiring between the lt. blue wire and lt green wire on the back of the vac. switch. I just disconnected the wires on the vac. switch for now.(No power in no power out) I wish people would learn that vacuum and computer controls aren't a bad thing. I should say that my 86s particular computer sucks so bad that gm says to get rid of it just so no one else has to.

[beamn7]

You converter has not been locked the entire time you've owned it.... It has to unlock when you come to a stop otherwise it would die just like driving a stick and coming to a stop without stepping on the clutch...
Most of these were set up to apply in 2nd gear, some 3rd.
They are made to unlock everytime you step on the brake pedal or low vaccum.
700's can overheat in 4th gear from running around with it unlocked
Sounds to me that the way you have described it = its working properly

[84_chevy]

my truck wants to stall out every time I shift it into gear. Could I have some of the same issues you guys are discussing here?

[beamn7]

Originally Posted by 84_chevy

my truck wants to stall out every time I shift it into gear. Could I have some of the same issues you guys are discussing here?

Yes, very possible. Disonnect the electrical connector on the drivers side of the trans (4 pin connector) and see what happens. If it stays running, you know it is an electrical issue, if not, it could be a stuck TCC solenoid or converter clutch stuck on. Another option is you could jack the rear wheels off the ground and see if it still does it. (dont step on the brake when you put it in gear, just get the wheels going right away)

Could also be unrelated to trans but worth checking into....

[gramps77]

Originally Posted by 84_chevy

my truck wants to stall out every time I shift it into gear. Could I have some of the same issues you guys are discussing here?

There are 2 wires that CAN come out of the connector at the trans. a blue and a red. Make sure someone didnt accidently wire in the blue wire instead of the red. The blue is for hooking up a switch if you want to manually lock the converter. The red goes through the brake switch and is energized when the brake switch is not acctuated.

[silversnail86]

I did say that the brake switch was working. After I hooked up the vacuum the system was working correctly except when cruising in third at 35mph it wanted to lock and unlock so a switch on the dash was my solution. Can anyone say for sure whether on not running with it locked Most of time if it hurt the TCC? I can now tell an obvious difference in all gears. I need a limited slip of some sort now!!

[beamn7]

I wired a normally open pressure switch inline on the ground circuit for the TCC solenoid and screwed it into the 4th gear pressure tap on the valve body therefore allowing for a 4th gear only TCC lockup and still running the power feed through the brake switch.
I don't like them coming on and off alot while driving, puts alot of pressure against the thrust bearing in the engine and pinging due to high compression in my case. The switches are readily available still from GM or there are a few kits you can install.
You can install the switch externally if you have a pre 87 (if I recall) or internally if not....

Here's a few:
http://www.google.com/#hl=en&cp=7&gs...w=1010&bih=531