I have the 6.2 that I put in my 1990 Blazer running. I
used the gas 700R4. How do I make the torque
convertor lockup? Is the lockup handled by the
engine ECU? If so, I assume mine will not be
locking up right now. I left the stock ECU in place and
just hooked up the glow plug controller, oil sender,
water sender, etc. My speedometer is working. It has
the electronic sender on the TC. Is this an indication
that the engine ECU is working? How can I tell if my
TQ is locking up? If it is not, how should I wire it to do
so?

Easiest way is have a tranny shop install the fully hydraulic tc control in it.

That is what I done with mine.Works great, depending on governer
weights/springs it will lock around 45mph with moderate throttle
pressure.

You can probably do it yourself, just not sure where you are to get the parts needed, it is not all that hard.

Brian alley.

Since posting yesterday I read that the TCC will
automatically lock at the appropriate time if the tranny
has a 12v signal from the ignition switch. I traced a
purple/white wire and a blue wire to the tranny. Does
anyone know which one should get the 12v+?

Briabn

There is a little more to it than that. Yes, Ifg you run a wire to the
tranny it can make it lock, but depends on how it is wired internally.
Some 700's were wired for 2,3 and od lockup, some for 3 and od, some
for od only. depends on the valve body setup inside. You could remove
everything except the od switch and wire from 12v to that and then the
solenoid, but the fully hydrauilic conversion works tons better.

Brian.

On Saturday I wired the TCC solenoid ground lead
(tan/black wire IIRC) to permanent ground and put a
switch in the pink/black hot to the brake switch. My
wife has therefor been manually (or womanually)
operating the toggle switch I installed to lock up the
TCC. I also added a light to indicate when the TCC is
locked up. Would the third pin (the one right next to
the tranny case, blue wire coming from it IIRC) be the
one to the od switch or is the od switch something
external to the trans? It sounds like you are saying
that there is a switch in the tranny that activates this
pin when it is in od. If so, wouldn't this switch work
off of ground, not positive 12v? If it does ground
wouldn't I want to wire the TCC solenoid ground pin
so that it is grounded by this od switch pin and then
the tranny would lockup in od only. I hope I am not
sounding disagreeable. I really am just trying to
understand what you are saying. It sounds like you
know the answer to my question.

there are so many variations it is ridiculous. The switches have two
pins on them, and make contact when they recieve pressure from the
vavle body. Therer are switches on 2nd,3rd and od on most 700's.

You can do away with the 2 and 3rd switches, but really need to lockup
in od, to keep heat down. trannie guys will say it will burn up right
away, but i run mine with no towing for a year with no lockup.

I now run only the hydraulic controlled conversion, and put that in all
of them I build. Works great, you would swear when my convertor locks
it has shifted another gear it comes on quick and hard.

I would find a competent trans guy and get him to do the swap for you.

that or buy a build book and learn yourself. While you are in there
pull the accumulators out, throw away and block ports to them, they are
a major weak point, leak and cause slippage.

Brian.

The tranny in this truck is a Mr. Goodwrench
replacement done by a shop. I assume it is the
correct year tranny for a 1990 K5 TBI 350. The plug
from the wiring harness does not appear to be
patched and it fits on the tranny wiring plug like it is
supposed to. The wire colors are purple, blue and
tan/black. Since there are only three pins, and I'm
pretty sure purple is TCC solenoid hot and tan/black
is TCC solenoid ground, I can't see how I could have
room for a 2nd or 3rd switch. Would it be reasonable
to assume that the 3rd pin is the od switch and that it
grounds when I am in od? If I leave on my dyi dash
mounted switch which gives hot to the purple (via the
brake normally closed switch) I can tell that the TCC
is locked up all the time. Thanks again for your help.

Brian

look along the pan rail, there should be somje number letter codes, I
can look you up a diagram by that. It should be right, unless when it
was replaced someone monkeyed around with it, which is common.

Brian.