Th350 behind 4.8ls

[Ricko1966]

It's usually that part. It especially blows my mind when it's an old guy like my dad that'll finally get over the fear of EFI but a computer controlled trans is a leap too far lol

I've been working off and on to try to figure out how to make a stand alone harness,and control a 4l60e with a factory computer. Want to fill me in?

 

[Ricko1966]

This guy hasn't even driven this truck yet. He doesn't understand how a turbo 350 operates,and everybody's already on the bandwagon for him to spend another 4000 to 6000 on a transmission change. Maybe this truck will never be driven on the highway or the advantage isn't worth the price. Maybe he's already spent every dime he can buying this truck and just needs help to get what he bought working.

 

[TotalyHucked]

I've been working off and on to try to figure out how to make a stand alone harness,and control a 4l60e with a factory computer. Want to fill me in?

Nope, my wiring skills leave alot to be desired. I just order the harness I need, BP Automotive will get my business for the next one

 

[Ricko1966]

I'll make it happen on my own NBD the wiring is the easy part it's all the other brain work figuring out what needs to happen to the ecm,what all sensors are mandatory etc. That's why I was adapting a Isuzu TPS to be a remote TPS. Not everyone has the same skill set,and budget for their project. So they run what is in their skill set, and/or what they can afford. Or even just what they need for what they are doing. Someone who's going to drive a truck 500 miles a year doesn't need an overdrive realistically.

 

[legopnuematic]

I've been working off and on to try to figure out how to make a stand alone harness,and control a 4l60e with a factory computer. Want to fill me in?

This wiki page on Sloppy Mechanics might be of value to you if you haven’t come across it already, the write up is focused on an 80E, but sounds like can be done with a 60E
Stand alone transmission controller

 

[AuroraGirl]

I've been working off and on to try to figure out how to make a stand alone harness,and control a 4l60e with a factory computer. Want to fill me in?

depends on the year 4l60e
If youre using an LS 4l60e there are like 3 distinct generations

There is the early, the input shaft sensor and changed solenoids i think in the early 2000s

Then there is late 2000s to 2013 or whenever for the 4.3 trucks, the trans went internal mode switch and actually was greatly reduced in complexity through various consolidations

 

[dirtscoots]

This guy hasn't even driven this truck yet. He doesn't understand how a turbo 350 operates,and everybody's already on the bandwagon for him to spend another 4000 to 6000 on a transmission change. Maybe this truck will never be driven on the highway or the advantage isn't worth the price. Maybe he's already spent every dime he can buying this truck and just needs help to get what he bought working.

Nailed it. I appreciate all the information that has come out in this thread. Personally I just want to be able to drive this thing. I do have another th350 sitting next to my k5 that I could try different parts off of. I was thinking trying to swap the torque converter. I’m not smart enough to dabble in internal parts.

 

[Ricko1966]

Nailed it. I appreciate all the information that has come out in this thread. Personally I just want to be able to drive this thing. I do have another th350 sitting next to my k5 that I could try different parts off of. I was thinking trying to swap the torque converter. I’m not smart enough to dabble in internal parts.

Okay,does it have enough transmission fluid,for sure? It is not a torque converter problem.Maybe a valve body problem. We should tag Nick @NickTransmissions on this one.

 

[Ricko1966]

Nope, my wiring skills leave alot to be desired. I just order the harness I need, BP Automotive will get my business for the next one

Actually I worded that wrong,not struggling with the harness,that's the easy part. The hard part to me is what needs to happen with the ECM

 

[NickTransmissions]

Nailed it. I appreciate all the information that has come out in this thread. Personally I just want to be able to drive this thing. I do have another th350 sitting next to my k5 that I could try different parts off of. I was thinking trying to swap the torque converter. I’m not smart enough to dabble in internal parts.

Are you still having problems w/your TH350? If so, are the symptoms more or less the same as reflected in your first post (takes ~3000 RPM to get it moving when in Drive)?

If so, have you checked vacuum at the modulator? What was the reading?

 

[dirtscoots]

Yes fluid is topped off. I have not checked the vacuum I’ll have to look up how to go about that. Thank you for the tip! I do have another th350 I could try to swap vacuum modulators as well.

 

[CountKrunk]

The 350 is a vacuum controlled transmission.

One of my vac hoses broke and the result was it wouldn't shift out of 1st gear.

Def make sure all your vacuum points are working right still.

 

[dirtscoots]

Would the speed cable hole being open make it not hold vacuum? I have a plug ordered for that.

 

[NickTransmissions]

Would the speed cable hole being open make it not hold vacuum? I have a plug ordered for that.

No.

Also, please quote my post if you would like me to respond. I dont get notifications which is intentional.

Let us know what your modulator vacuum signal is. If it's at least 13Hg and modulator itself is functional, mod valve not stuck then the problem is inside the trans

 

[AuroraGirl]

You must be registered for see images attach

Would the speed cable hole being open make it not hold vacuum? I have a plug ordered for that.

This is the bottom of a TH350 ,, the modulator visible is the original modulator. if the modulator looks like that, you should get a new one simply because of age in my opinion. the hose to it needs to be short from a metal hardline that has a hose on the end by the intake manifold, that connects behind the carburetor to the intake with a small hose. the line sometimes rusts so keep an eye out for that.

You must be registered for see images attach

if the modulator is like this (much smaller than the big can in the previous photo) then its not that old and id say dont replace it without having a verified reason to do so