What's new
CK5
Register an account today to become a member! Once signed in, you'll be able to participate on this site by adding your own topics and posts, as well as connect with other members.

4L80E dropping into limp mode

TerryD

TerryD

Mildly demented...
 Premium
Joined
Jul 27, 2008
Posts
5,842
Reaction score
4,174
Location
Covington, Va
My 2000 K2500 5.7L/4L80E truck keeps dropping into what I assume is a limp mode. It stops locking up the TCC, no engine braking and you have to be going over 60mph to get into 4th.

No CEL, no obvious issues. No repeatability that I can see.
 
Plugged filter?
Get a good diagnostic scanner on it as it happens and check the trans fluid temp maybe.
I was thinking they won't go into lockup unless it IS in 4th. That may only be the 4l60.. not sure.
 
The 4L80 in my truck locks the converter in 3rd.

I'm going to try a drain and fill, followed shortly by a filter change so it's not such a shock to the system.

Does anyone know the TCC slip threshold? I'm seeing over 200rpm differential on my cheapo scanner under heavy load in 4th. Wondering if that's the issue. May be time for a TCC solenoid.
 
  • Like
Reactions: HBD
200 rpm slip is not good. The converter lining itself may be failing. It can also be the whole circuit for the TCC. The TCC valve itself is known to wear in the VB. Sonnax and trans go make repair valves for this. Some require tooling to resolve. If it’s seeing that much slip it will stop commanding lockup.
 
The hydraulic circuit allows lockup in 3rd or 4th, depending on the program.

I didn't see a tolerance in my ATSG book, when fully locked it shouldn't slip at all, it's only programmed to slip into lock to not be harsh, but once locked it should not slip.
 
I towed the empty trailer out to breakfast this morning. TCC slip numbers were very low. Under 20 for most of the drive. It looks like it is likely the TCC valve causing the issue under heavy load.

I'm gonna do a drain and fill to clean the pan, then order that Trans-Go valve and do a new fluid and filter change when I do the valve.
 
TerryD said:
I towed the empty trailer out to breakfast this morning. TCC slip numbers were very low. Under 20 for most of the drive. It looks like it is likely the TCC valve causing the issue under heavy load.

I'm gonna do a drain and fill to clean the pan, then order that Trans-Go valve and do a new fluid and filter change when I do the valve.
Click to expand...
You have to remove the valve body, in order to do that TCC valve bore job. You might as well replace everything like shift solenoids and internal harness. As far as the Trans Go shift kit I am not the biggest fan of that. The Trans Go shift kit comes with some small valve body filters and o-ringed end caps that are good to use. The small screen filters one is cone shaped and the other goes inside the shift spool valve.
 
Not a bad vb to drop. Get some vb separator plate gaskets as well. I would do the on/off mods with the valve as well and the hd spring in the kit.
 
1-ton said:
You have to remove the valve body, in order to do that TCC valve bore job. You might as well replace everything like shift solenoids and internal harness. As far as the Trans Go shift kit I am not the biggest fan of that. The Trans Go shift kit comes with some small valve body filters and o-ringed end caps that are good to use. The small screen filters one is cone shaped and the other goes inside the shift spool valve.
Click to expand...
Do you have to remove it if you're not doing the full lockup mod that requires drilling the holes?
 
TerryD said:
Do you have to remove it if you're not doing the full lockup mod that requires drilling the holes?
Click to expand...
I was thinking you where going to do the actuator feed limit valve kit, which is the most known problem the 4L80E trans have. With that TCC valve kit I am not sure if you need to remove the valve body. If you do remove the valve body when you remove the separator plate some check balls are going to fall out.
 
Last edited:
1-ton said:
I was thinking you where going to do the actuator feed limit valve kit, which is the most known problem the 4L80E trans have. With that TCC valve kit I am not sure if you need to remove the valve body. If you do remove the valve body when you remove the separator plate some check balls are going to fall out.
Click to expand...
Can you explain that kit? Is it something I need to look at?

I'm considering the reprogramming kit. Been a while since I've been in a valve body but I think I can still figure it out.
 
TerryD said:
Can you explain that kit? Is it something I need to look at?

I'm considering the reprogramming kit. Been a while since I've been in a valve body but I think I can still figure it out.
Click to expand...
The feed limiter valve bore is known for wearing out on 4L80E transmissions. It is a common problem. If your transmission has ever been rebuilt by any shop, or replaced by any remanufactured trans the feed limiter kit has very likely already been installed because it is a common practice by all rebuilders to fix that. Since your transmission is from a truck that is 23 years old, and has a lot of miles on it then it has probably been rebuilt at some time...hard to say. I would stay away from the Trans Go shift kit. It has some cool stuff in it, but some of it sucks like the 3-layer separation plate, and especialy the spring loaded pressure relief deal. If you do remove the valve body you may want to look into some plastic check balls from a company called Sonnax. They have a lot of cool stuff for the 4L80E trans.

34200-16K_Combo.jpg
 
TerryD said:
Can you explain that kit? Is it something I need to look at?

I'm considering the reprogramming kit. Been a while since I've been in a valve body but I think I can still figure it out.
Click to expand...
I have always liked the results from Transgo kits personally. I did the HD2 in my '01 almost 3 years ago. I have been very happy with it. The biggest question for me was what sizes for drilling the separator plate because I like firm shifts, but didn't want my wife complaining about how hard it hit, like my old trucks do. We got it just about right, in my opinion, but the shift firmness is something that everyone has a different opinion about.
I did the limit valve repair kit as well, but didn't everything that I could, just a rebuild and slightly looser convertor from Phoenix Transmission.
I did replace the shift solenoids and TCC solenoid with Delco parts, even though the transmission worked fine before opening it up, it just had 270K on it. There were a few hard parts replaced as well as the normal things, of course.
 
1-ton said:
The feed limiter valve bore is known for wearing out on 4L80E transmissions. It is a common problem. If your transmission has ever been rebuilt by any shop, or replaced by any remanufactured trans the feed limiter kit has very likely already been installed because it is a common practice by all rebuilders to fix that. Since your transmission is from a truck that is 23 years old, and has a lot of miles on it then it has probably been rebuilt at some time...hard to say. I would stay away from the Trans Go shift kit. It has some cool stuff in it, but some of it sucks like the 3-layer separation plate, and especialy the spring loaded pressure relief deal. If you do remove the valve body you may want to look into some plastic check balls from a company called Sonnax. They have a lot of cool stuff for the 4L80E trans.

34200-16K_Combo.jpg
Click to expand...
What kit do you prefer and what makes you like it better? We used Trans-Go stuff in a couple transmissions growing up and had good results from them.
 
Transgo makes the best shift kits in my opinion. If you are completely rebuilding it you can get around the stacked plate by doing the dual feed direct mod internally, but if you are simply just wanting a shift kit in the vehicle without removing the trans, the Transgo kit is the best there is that I am aware of.
 
The Trans Go kit has mostly about curing high line pressure problems the 4L80E has. They use a 3-layer separator plate as a back door way of dual feeding the 4L80E tarns, which is a cure for high pressures. The only problem is the 3-layer separator plate can cross leak, which can lead to serious problems. There also a spring loaded pressure relief deal in the kit that is known for jamming wide open, and killing the transmission. All the other parts of the Trans Go kit are about tightly sealing the valve body which is another problem 4L80E trans has. Those are the good parts of the Trans Go kit. The Trans Go kit also comes with a pressure control valve that is better that the stock one. The only part of the Trans Go kit that are for increased shift firmness is drilling out the separator plate holes. For a truck I go with the smallest diameter drill. The one thing I would recommend is a Sonnax line to lube spool valve. That one thing cures just about all high line pressure problems the 4L80E has.
 
So if I did the Trans-Go shift kit, the Trans-Go TCC spool valve and the Sonnax line to lube valve, that would probably cure the majority of my issues and me not have to pull the transmission.

Or am I doubling up some things that won't cooperate.
 
You must log in or register to reply here.

Latest Posts

Top Bottom