Do you still use the TH350C vacuum switch?
Does anyone have a drawing of the non-computer 700R4 setup?

I'm still confused by this lockup connector 3rd prong.
Measured it to be connected to a temperature sender in the transmission, this is also mentioned at the Bowtie site. (Cooling section)

After all this talk here about trans temperature I planned to hook this up to a gauge.

But looking at the 1987 Corvette drawing it's shown that the 3rd wire is a 4th gear signal switch in the 700R4....?....

 

IF your trany is same as the '87 vette shown...connect pin D to pin B and forget about it,....it will lock ONLY in 4th gear....
now many trannies have also parallel switches that are activated by 2 and 3rd gear also....and can lock up in second and 3rd gears too....that can be herky-jerkey to drive,...so I"d disconnect that function by simply cutting the wire inside the tranny pan, if necessary....
you see one of the functions was for the computer to for sure know when 4th was activated, so to for sure lockup....but computer had option to lockup at any time, according to the chip....

that's why the thing was wired that way in '87 vette....maybe other cars too....

GENE

 

Thanks Gene!

I get your point by connecting B to D to have only 4th gear lockup.

But what I found was that my trans is like this:


The model number tells that I have an 1987 transmission.
I was wrong about the date of the drawing, its from 10-87 which I guess means that it's for the 1988 corvette.
Maybe there was a change from 87 to 88.
As seen the 3rd prong (B) is connected to a temp sensor in the 700R4. This is also mentioned at the Bowtie site, at http://www.700r4.info/Conversions/68...6881vetp9.html
The 4th prong is not used.

My 1980 had a vacuum switch in series with the brake switch. See below. Should this be shorted with the 700r4?
Then I just connect the existing lockup wire to prong A and ground prong D.

 

Hmm, just found some new info at Bowtie:

http://www.700r4.info/tech/WhitePaper/PDF/GM_Switch.pdf

Now I'm really confused.
The drawing indicates that:
Pin A is connected to the solenoid through the 4th gear switch.
Pin D goes directly to the solenoid.
Solenoid is internally grounded.

I tried to measure between pin D and trans case and it's open. Should have been below 100ohm if Bowtie drawing is correct.

At least the Bowtie drawing is different from the GM drawing.

 

 

I wouldn't want my converter to lock only in 4th, you'd be at a 20-30 horsepower loss in a drag race. I have mine lockup in the top of second where everybody has told me it should be. You may also want to think about putting in a manual switch, like GKull.

 

I disconnected the vacuum switch/wire that runs to the trans from the firewall and chose to use the wiring configuration included from bowtie. The trans locks up fine in third and fourth. I've noted some lock-up in 3rd when I had yet to hit 4th gear (down-shifted to third when trans had yet to hit 4th and got disengage). Lockup disengages at touch of brake pedal.

I run the wires from trans up through the shifter cable hole and then to underside of dash where I attach to brake release switch, an accessory power source and then ground on the steering brace. Works fine.

 

Ingar, thing is, without knowing exactly what your tranny has internally and which pins it's going to,....It's hard to help.....
I have no idea what the 'stock' configuration was, much less what modifications were done....
but in general Pin A goes through a brake switch to +12 source...and pin D is the negative grounded end of the solenoid...now that being said...it can go through the internal switches to tranny case ground, through the computer with other imputs to the computer off pins B and or C or just plain hooked up internal to tranny without any computer controll at all....
and on top of that, yes 4th hear most allways locks up, but that is not all
sometimes there is a switch on the 2-3 valve that can lock it up in those gears also....and that is internal to tranny on end of valve body next to the 4th gear switch....so without dropping the pan, and tracing wires, it's hard to tell what's what...but I suspect if you just try using A pin for +12 and D pin for grounding somehow...computer, switch, etc...you will find the unit sasisfactory.....
I have all the gear switches....2-3-4 in mine, plus a grounding switch on my '7730 computer OR direct ground...meaning that the computer can lock it up at 50 mph per the chip...OR I can get it to lockup at any speed, soon as it's in 2-3-4 gears......nice chirp and bump in the butt upon shifting...but I"m told that is hard on the TCC clutches....mine's been fine for 4 years now though...

GENE

 

Gene:
I thought all 700r4 were wired the same from GM and that there was an error in one or more of the drawings.
But I now realize that the internal wiring might be different to various cars, my trans came from a 87 Caprice.
Also, Bowtie say that they wire their 700r4 which I guess explain the drawing at their site.

Anyway, I'm going to install TPI this winter and would like to wire my trans for this before I fill it with oil....

TedH: Since you have a 1980, why didn't you just use the TH350C lockup cable?

I have a bottom view of my trans with comments at http://iotech.no/corvette/div/700r4bottom.jpg (to large to post..)
I would be glad if someone can verify that the switch in my 700r4 is for 4th gear. Then I can just rewire my trans for TPI.

 

when i got my 700r4 from bowtie i was advised that since i had no computer controll,that they "gutted" the tranny so lock-up would only occur in 4th gear. when i got mine from bowtie they only advised to have all wiring issues resolved before calling for the test of the tranny.they also did not sell wiring harnesses or kits at that time. so i ordered a TCI kit from Jeg's,it came with a vacuum lock-up switch,wiring harness,pressure switch and instructions. i mounted the vacuum switch and Bosch brake relay(from bowtie) on the firewall in front of the driver,to the side of the power brake booster. i also wired in a 5 amp blade fuse device for protection. when i initially hooked it up, i'd blow the 5a fuse when lock-up occurred. i found that bowtie had wired the tranny one way and TCI needed it wired another way. so i dropped the pan and made the changes according to the TCI diagram,took about 5 minutes. put a new fuse in and it's has worked fine ever since.

 

Thanks Gary! That confirms the Bowtie transmissions are rewired.

I've added some drawings of possible hookups at the 700r4 page I'm working on. At my page under technical.

 

Ingar,I hate to have to drop out on you here, but it's been 4 years since I did my install, your pix there is same as I remember my tranny, but that blue sensor was another switch, as mine locks in 2-3-4 I had thought wiring it permantly to +12 without any brake/other switches in there would be fine, as when stopping the tranny would downshift to first at some point and thereby release the lockup,....but it did not work that way...dunno why....so I put my own relay in my brake light circuit...and that opens the contacts when brakes are aplied....so the grounding is done by the computer OR, directly, console switch selected by my desires at moment....smooth computer operatiion....or herky jerky stickshift feeling....
of couse if I want to bark gears, the non-computer position is used....

GENE

 

Thanks again Gene!
I think I will use the setup below. That makes it possible to change the functionality without open the transmission. I can rewire it externally when I install TPI and full computer control.
I will install a switch like you describe to see how it behaves when locking up in all gears.....

Drawing is based on all 4 pins present at the connector.
Unfortunately I will loose my temperature sender since my connector doesn't have the C pin.



[Modified by Ingar, Norway, 11:47 AM 12/14/2001]

 

Ingar, your tranny MAY lock up in 1st gear, stalling the engine with your arrangement....try it....but the ground side of the internal gear/lock switches needs connected to the manual switch or the computer output, which also grounds when commanded....that would make it an additive thing.....2-3-4 what ever gear if you have the switches, brake relay in +12 closed, and then ground selected by either manual switch which needs 2-3-4 internal switch to be closed, or the computer grounding...same thing...

so to lock, it needs at least one internal switch closed, plus either computer or manual switch, plus of course brake light relay....

simple really when you think about it, but a nasty mess to change internal wiring....so be sure of internals before pan in place.....

GENE

 

Gene, I must connect it internally as shown on the drawing to allow for adapting it to TPI later without internal rewiring.
The functionality with this setup is really the same as shown on that Bowtie drawing I referred to.

When you say 2-3-4 switches, do you mean separate switches for all these gears or a common pressure switch indicating one of them to be active?

 

Ingar, AS I RECALL, the 4th gear switch was by itself....the 2-3 gear switch was one unit mounted on the 2-3 shift valve section of the body....
just like the 4th gear switch....now just how that worked mechanically, I don't know....as I would assume that valve would change positions and flip the switch....but it closed the switch in 2&3 gears...and must be able to open it between shifts, I presume....I"m not sure....

anyway, as long as you lockup in 4th at 50mph or so, your' fine....

 

Went the painless route and followed BowTie directions for their (BowTie) harness.