Well guys, this is Ronaldo, and am here for a real challenge that drove me crazy about my transmission
and am really, really really and disparately in need for a help.

The Problem Statement:
My truck shifts perfectly once it is started, but after driving it for about 10 miles on highway than it would have a hard shift 2-3 and 3-4, but If I shut the engine off for one min and start it again it would shift perfectly until driving it for another 10 miles, some times it would shows "Transmission Hot" . But after the repair that I have done, I do not see this message


Diagnoses/Repairs Made:

I have connected my OBD and it showed P0894 "Transmission Component Slipping" and according to the service manual and GM TSB, it appears to be a TCC related problem. and there are no other DTCs at all!

What have been Done:

1- Changed ATF --- Problem still exists
2- Changed transmission solenoids (Force motor and the TCC PWM sol) --- Problem still exists
3- Changed the whole transmission including the TC with a guaranteed Used transmission --- Problem still exists (so i returned my original transmission)
4- Tested all connections from PCM to Tranny's 20-pins connector. found the connector is fully filled with ATF.
5- Flushed the ATF cooler using 100 bar compressor, it seems to be blocked, (I ve disconnected the hoses from the tranny during this process).


The hard shift has been reduced but it stills there.



Notes:
• There is no way to change TC since it would cost me like $1000+ (am not in the US to find this part easily)
• Although there are many mechanics own Tech2, but they use it as a code reader (that is what happen in my country :mad:)
• I went to a stealership and they suggested to change the Trans -- which I have already did ! and many other owners experienced this same issue after changing the tranny
• I have an online access to the service manual but i didnt helped so much (www.alldatadiy.com (http://www.alldatadiy.com))
• I have searched allover www before posting this thread
•

1. Fluid level okay while running, warm, level surface. OK
1a. Fluid color and smell------- Good pink/red color, smells very good ;)
2. Speedometer reading correctly ---- Perfect
3. Shifting normal/hard----- Normal but very hard after highway drive.
4. Shifting into OD okay? ---- OK
5. Any service engine light: yes/no ---- Yes
6. If SES light on, what codes do you have? ---- P0894 "Transmission Component Slipping"
7. Model year: 2006
8. Describe symptoms: See above
9. Does the engine come up to full temperature? No
10. Any service work recently done that may contribute to your issues. No service done before problem
11. Does the TCC lock up (or how many "shifts" do you hear?) --- I dont feel TCC lockup, it shifts the 4 gears
12. Are you experiencing any kind of slipping? ---- No
13. What type of rear do you have? 4.10
14. If you have an accurate tachometer, what is the RPM at 55 or 65? about 2200RPM @ 65 MPH



2006 Silverado
2500 HD, 6.0 V8-Gas , 4 Speed Auto 4L80e, 4X4

Transmission cooler blocked? Sounds like the pump is building too much pressure with the cooler blocked.
Which cooler is blocked, the external cooler or the one integral with the radiator?

I think the internal cooler, but am not sure since I have flushed them all together.

You are suffering a slippage. Well known in the GM world.

2- Changed transmission solenoids (Force motor and the TCC PWM sol) --- Problem still exists
You rolled the dice and came up seven's.

Here is your problem.

The Torque converter solenoid "controls" a hydraulic signal.

This hydraulic signal is sent through a valve. Consider the valve going east and west. The hydraulic signal is passing north to south.
There is leakage. You are noticing it when the fluid is getting hotter thus thinner.
The blue arrows represent the valve.
http://i120.photobucket.com/albums/o187/USMILRET/4L80E%20Transmission/bottomforwardviewtcc.jpg

This is a schematic if a like minded TCC valve:
The red represents the hydraulic signal going to the TCC Control valve within the transmission's pump. The hydraulic signal contols that valve.
If it gets too weak due to leakage it will not control the TCC Control valve.
Take a look at the right of the schematic. TCC PWM ON. It doesn't leak. Only the Red/left side does.
How it works. The computer detects engine RPM. Detects Vehicle speed, Detects Transmission input speed. Detects engine load.
Engine speed and transmission speed "when matched close enough" The computer permits the TCC solenoid to start pulsing. It does this by electronically closing the ground. Slowly with less ground and by the time the Torque converter is "applying enough" It will complete the grounding 100% fully engaged.
It can leak at any time in this process. Think of it like this. You using a leverage. That leverage uses leverage. You can understand why the end result is slippage.
The computer will go into safety mode when it detects Transmission component slippage. Line pressure is increased and shifts harder.

http://i120.photobucket.com/albums/o187/USMILRET/4L80E%20Transmission/TCCsolenoidleak.jpg?t=1263650298

Someone makes a kit that reams out that bore and installs a sleeve and an improved valve iirc.


Edit: I found them

http://www.sonnax.com/part_summary.php?id=3624&pl=3

http://www.sonnax.com/part_summary.php?id=4975&pl=3

I think only one of these has you ream out the bore, the other is preventative maintenance.

This is a schematic if a like minded TCC valve:
The red represents the hydraulic signal going to the TCC Control valve within the transmission's pump. The hydraulic signal contols that valve.
If it gets too weak due to leakage it will not control the TCC Control valve.
Take a look at the right of the schematic. TCC PWM ON. It doesn't leak. Only the Red/left side does.
How it works. The computer detects engine RPM. Detects Vehicle speed, Detects Transmission input speed. Detects engine load.
Engine speed and transmission speed "when matched close enough" The computer permits the TCC solenoid to start pulsing. It does this by electronically closing the ground. Slowly with less ground and by the time the Torque converter is "applying enough" It will complete the grounding 100% fully engaged.
It can leak at any time in this process. Think of it like this. You using a leverage. That leverage uses leverage. You can understand why the end result is slippage.
The computer will go into safety mode when it detects Transmission component slippage. Line pressure is increased and shifts harder.




Hi GenBiltstein sorry for late response, thanks for these info, but I have changed the whole transmission and the problem exists, this makes me crazy. Do you recommend removing this valve from the valve body?

and while surfing the www, I have so many people having the same problem even after rebuilding the transmission and this makes me more crazy up to the point that am dreaming at night about it!

Someone makes a kit that reams out that bore and installs a sleeve and an improved valve iirc.


Edit: I found them

http://www.sonnax.com/part_summary.php?id=3624&pl=3

http://www.sonnax.com/part_summary.php?id=4975&pl=3

I think only one of these has you ream out the bore, the other is preventative maintenance.

Do you think the first one should solve the problem?
I think the first one is more easier to install for a shade tree mechanic ;)

Do you think the first one should solve the problem?
I think the first one is more easier to install for a shade tree mechanic ;)


Well, the first one replaces parts with fairly stock parts, which is replacing worn parts which would probably work and be very easy. Unless the bore itself is very badly worn or scored, you won't be able to establish that until the VB is out.

The second one is a "once and for all" sort of kit. It would appear you need some kind of jig to put the VB in so that the reamer goes in strait then ream it by hand with a speed handle.

Modifying the valve body itself makes me nervous, but when I installed my transgo I had to drill big holes in it in places so I'm a little desensitized.


I really considered doing this mod the last time I had my VB out when I installed the HD2, and if I had it to do over again I probably would. I didn't want to complicate things though, that was the first time I'd ever dropped a VB.

It fixes a problem that's not so much a matter of if, but of when.

I also like the fact that you can make the apply more firm. I'm not a bigt fan of gradual apply.