4l80e failing after going on overdrive

[jfge8618]

I got a 2002 sierra 6.0 with the 4l80e, the truck runs good until it catches the overdrive after slowing down the truck seems its not dropping gears. if I get to a full stop it wants to stall. The other thing is that reverse barely catches after and slips quite a bit after it goes on O/D. But I does not do it if it does not goes into O/D

I have replaced the filter and did a flush of the sistem.
The only thing I've noticed is a leaking plug on the connector part and I'm in the process of sealing with rtv as I've read here.

Any other ideas?

 

[NickTransmissions]

I got a 2002 sierra 6.0 with the 4l80e, the truck runs good until it catches the overdrive after slowing down the truck seems its not dropping gears. if I get to a full stop it wants to stall. The other thing is that reverse barely catches after and slips quite a bit after it goes on O/D. But I does not do it if it does not goes into O/D

I have replaced the filter and did a flush of the sistem.
The only thing I've noticed is a leaking plug on the connector part and I'm in the process of sealing with rtv as I've read here.

Any other ideas?

Your transmission harness needs to be replaced - id also continuity test all of your solenoids (see my video here for procedural details).

It sounds like your converter clutch is not coming off when it should. It can also be an engine-related issue.

Do you have a bidirectional scan tool that can render live engine and transmission data while you're driving?

 

[jfge8618]

Your transmission harness needs to be replaced - id also continuity test all of your solenoids (see my video here for procedural details).

It sounds like your converter clutch is not coming off when it should. It can also be an engine-related issue.

Do you have a bidirectional scan tool that can render live engine and transmission data while you're driving?

Hey there, I went ahead and ordered a harness, I have the valvebody off I'm in the process of testing the selenoids and tcc valve I'll be rigging a pump to do a vacuum test.
All of them clic once jumping them on 12v but the epc selenoid I noticed it gets warm ver quickly and also noticed on the casing bluish tin to im thinking its overheating.

I don't seem o have an ohmmeter any more so I'll buy another one tomorrow to check.

And sadly I only have a bluedriver as a scanner.

But the code it gave me was a P0730

Ps I was literally looking in you YouTube just before I saw you reply it's great to have guys like you that take the time to explain In detail.

 

[NickTransmissions]

Hey there, I went ahead and ordered a harness, I have the valvebody off I'm in the process of testing the selenoids and tcc valve I'll be rigging a pump to do a vacuum test.
All of them clic once jumping them on 12v but the epc selenoid I noticed it gets warm ver quickly and also noticed on the casing bluish tin to im thinking its overheating.

I don't seem o have an ohmmeter any more so I'll buy another one tomorrow to check.

And sadly I only have a bluedriver as a scanner.

But the code it gave me was a P0730

Ps I was literally looking in you YouTube just before I saw you reply it's great to have guys like you that take the time to explain In detail.

Cool, man - thank you for the views. Sounds like the EPC may be at issue - once you have your DVOM to test it, you'll likely know for sure. The harness is a source of frequent issues on the 4L80Es so replacing is always a good move, regardless.

Let us know what you find out once you test everything.

 

[jfge8618]

Cool, man - thank you for the views. Sounds like the EPC may be at issue - once you have your DVOM to test it, you'll likely know for sure. The harness is a source of frequent issues on the 4L80Es so replacing is always a good move, regardless.

Let us know what you find out once you test everything.

Well I did test all selenoids and all of the tested ok.
I also tested the pressure switch and I'm getting higher ohms reading on PRND43 switch between 8 to 20 and rest of the positions read between 3 and 5 at max

So I'm guessing I'll be replacing that too...
And I have not had chance to vacuum test the valvebody.

 

[jfge8618]

Finally I got to check the valve body and came to find out it didn't have any gaskets neither the upper lower or the acumulator.

I went ahead and cleaned the entire thing and checked all o-rings and filters etc seem in really good condition.

I managed to get a set of gaskets ill put those in with the orings, the pressure switch and the harness and see what happens.


Why would who ever built the trans not use those gaskets?

Ps I just bought this truck and as I take it apart I noticed the trans was rebuilt recently. but now I'm scared lol

 

[NickTransmissions]

Why would who ever built the trans not use those gaskets?

Sounds like retards were into it before you got it...It's unbelieveable but every once in a while ill see one come in with no gaskets, lol.

Yea, let us know how it turns out.

 

[jfge8618]

Well I did all of this and it seems the damage is done still getting the same symptoms it does change gears smother tho. But I think the torque converter is fried.

 

[NickTransmissions]

Well I did all of this and it seems the damage is done still getting the same symptoms it does change gears smother tho. But I think the torque converter is fried.

Sucks, sorry to hear that...Id yank it out for overhaul and TC replacement. You can do some choice, cost effective upgrades when going back together with it.

 

[jfge8618]

Sucks, sorry to hear that...Id yank it out for overhaul and TC replacement. You can do some choice, cost effective upgrades when going back together with it.

Well I'm all ears lol. It's gonna be a couple of weeks when I get to it plus I'll have to order stuff form the US, I'm living on mexico at the moment and parts are some what scarce or way to expensive where I'm located.
So yeah I'm all ears for recommendations.