700r4 lock-up

[Ricko1966]

Well Damnit for some reason I thought you had an 85 I found a schematic for an 85. Is you're truck a carbureted 49 state car? If so I'd use this as schematic as a reference anyway.

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[BJedi76]

Sooo…

is this an ECM or a TCC?

knowing this will help decide how I have to approach this.

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[BJedi76]

I followed instructions to bypass an ESC.

The wire colors matched, so I didn’t even think about it. I’m guessing I was wrong and it’s an ECM.

it starts and runs fine. It even revs. It has no issue in first gear, But after it shifts I can’t drive the truck at more than 10% throttle or it loses all power.

as soon as I back off to about 10% throttle I get all the power back and the truck continues to drive, without issues.

If I keep it at less than 10% throttle, Eventually I can get up to 55-ish, but at any point if I push the throttle further than about 10%, all power goes away & as soon as i back off the throttle, all power comes back.

 

[Ricko1966]

Sooo…

is this an ECM or a TCC?

knowing this will help decide how I have to approach this.

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That's the ESC controller.

 

[BJedi76]

Sorry…

I meant ESC, not TCC.

 

[BJedi76]

So does that mean I do not have an ECM?

this box is mounted up under my dash behind the glove box.

If I do not have an ECM, why does my truck lose all power upon shifting.

 

[BJedi76]

If I do not have an ECM, does the ESC have “ANYTHING” to do with shifting?

 

[Ricko1966]

This is 100 percent gut feeling and just a guess, but humor me. Make a mark on the manifold and distributor base so you can put things back if you have too.Now loosen the distributor hold down and twist the distributor body itself 1/2 inch counter clockwise, lock the distributor down and take a test drive. Is it better ? Twist it a little more, post your results. I'm theorizing you have your initial timing wayyy to low when it shifts, and you lose all the centrifugal and you step into the throttle and lose all your vacuum advance your timing is so slow it won't run.

 

[AuroraGirl]

This is 100 percent gut feeling and and just a guess, but humor me. Make a mark on the manifold and distributor base so you can put things back if you have too.Now loisen the distributor hold down and twist the distributor body itself 1/2 inch counter clockwise, lock the distributor down and take a test drive. Is it better ? Twist it a little more, post your results. I'm theorizing you have your initial timing wayyy to low when it shifts and you lose all the centrifugal and you step into the throttle and lose all your vacuum advance your timing is so slow it won't run.

Are you sure it’s not an ecm.. I have a 1990 ecm in my scrap pile that looks just like that... OP can I see your computer side ways to see the terminal? If you open the screws on one side do you open up to reveal a narrow chip with a blue cover that is pushed into the contacts?

 

[AuroraGirl]

Gm transmissions didn’t use electronic controls until the early 90s but they definitely could have electronic components such as something that interacts with a vacuum switch for lockup on a tcc

 

[BJedi76]

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[AuroraGirl]

Nvm that’s a lot smaller than I thought same general shape as what I thought. Ur good esc.

 

[BJedi76]

I ordered the Painless 700r4 kit.

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[BJedi76]

There were other, less expensive, kits, but they seemed to be more about bypassing than replacing.

… and several of the other kits had a manual switch, which I don’t want.

for some reason, I couldn’t buy direct from Painless and had to go through Summit.

 

[BJedi76]

Why does this kit come with an external pressure switch?

Can I not get the internal pressure switch(es). I haven’t even looked, yet.

I assume that’s with the little silver canister that screws into the transmission, is for.

what is the point of bypassing things that are already there?

Did I buy the wrong kit?
I (apparently wrongly) assumed that this kit was simply, modern replacement parts.

everything in the kit seems to simply replace things that I already have, except that little silver pressure canister.

Anyone care to explain this to my dumb ass..?