4L80E with P0894 and lockup issues-looking for new ideas
08-02-2012, 05:13 PM
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4L80E with P0894 and lockup issues-looking for new ideas Hello all,
I am a new member to these forums but I have been looking over posts for awhile and have found some very useful information so I finally joined. I am a fairly young tech and just finished my apprenticeship last fall. I will warn that this is a LONG post but any help and insight would be greatly appreciated.
I recently bought a 2006 2500hd with the 6.0l and a 4l80e knowing that it had tranny issues. When I first scanned the truck it had a pending code of p0894 indicating that there was component slipping. Around town it was fine with no real symptoms at all but the truck had a harsh 1-2 shift with all other shifts being really firm after driving on the highway.
After looking through many service bulletins and other resources, as well as talking to a couple different transmission shops, the general idea was that the converter was most likely the cause and that the piston ended up cracking inside. So I ordered up a Precision of New Hampton converter along with a TCC regulator solenoid.
I installed both the converter, solenoid, and a new seal at the pump. Along with a new filter, I flushed the lines with brake clean and shop air (was told that it should be enough if the pan was clean; and the pan was really clean). The filter had some larger chunks of clutch material in it. Fluid level was correct.
I took the truck for a drive (20 minutes) and it felt great around town but once on the highway it was shifting even harder than before and the temp gauge was around 190 degrees F. I parked the truck and made a couple of phone calls to some shops around town as well as a dealer tech who said that it might just need to relearn the shift pressures and that I should clear any pending codes (P0894).
So I cleared the codes and took the truck for a second drive (20-25 minutes). The results where the same; good in town but getting hot on the highway and harsh shifting. I was on my way home and the gauge was at about 220 degrees F at which point the truck started to slip in drive and even reverse. So I instantly shut it down and waited for it to cool off. Once cold the truck wasn't slipping or anything and shifted good.
I pressure tested it and all of the numbers were within spec when I controlled the current to the EPC motor. The pump will produce about 177psi at 0.02 amps to the motor. When in park I have 60psi, R-90psi, N-60psi, D-55psi, 3-55, 2-between 40 and 55psi, 1-50psi (all of these pressures are static with the park brake on). GM states that drive, park, and N should be between 35-171psi with reverse being 67-324psi.
I dropped the pan again and found a large amount of VERY fine clutch material with no big chunks like I found in the filter the first time. Fluid was burnt. I also found to my horror that the TCC PWM solenoid was pushed out a ways and when I removed it that the most inward o-ring was over the screen on the solenoid where 2-3 fluid is supplied. I believe the clip was not seated on the correct part of the solenoid and I am kicking myself for that now.
I proceeded to drop the valve body to make sure nothing was stuck in any of the bores. Both of the filter screens (EPC and the TC one in the case) were ripped open. All of the valves moved freely in the bores and there was no major debris in it.
I bought a new valve body anyways thinking that it might be a good idea at 160,000 miles on the one that was in there. I had both the rad and the external cooler professionally hot tanked then I flushed them after with Dr. Tranny Kooler Kleen.
I installed the new valve body and put a massive in line filter (30" reverse osmosis high flow filter) before the coolers to catch anything that was still in the converter before going into my now clean coolers.
The new VB was installed with GM gaskets and a GM filter. Dex VI was used and I took it for another drive with the scanner (snap-on Solus) and pressure gauge still installed. Pressures looked good driving down the road but P1870 count was at 2 before hitting the highway and in 4th gear at lockup I had between 180-380 rpm of slip with TP at about 10-30% cruising.
It shifted closer to my initial drive before I even touched the truck after going on the highway and check engine light came on. Transmission temp was drastically lower at about 110-150 degrees F.
I have yet to drop the pan again and have a theory that it would have been better if the solenoid fell right out. I think I have glazed the TCC because of the solenoid but I am looking for other ideas of what else I should check before I burn up another converter. I read on bulletin #08-07-30-008B that the converter clutch valve in the pump must have a travel of 13mm, how is that checked?
Also I am worried about the cause of the truck slipping in all gears even reverse. I know that some material might have got into the old EPC motor because of the ripped screens and blocked a passage (why I changed out the VB) but is there any other things I should consider? My other thought was that it might have got hot enough to try and lock the TCC in order to try and cool it off but if it was just leaking past the solenoid it wouldn't have helped and just might have slipped at the locked TCC.
I have come to terms with the fact that I most likely screwed the current TC but don't want to screw another one.
Any help would be greatly appreciated! I am currently out of ideas and I think in need of some fresh insight.
Thanks for reading, I know it was long
I am a new member to these forums but I have been looking over posts for awhile and have found some very useful information so I finally joined. I am a fairly young tech and just finished my apprenticeship last fall. I will warn that this is a LONG post but any help and insight would be greatly appreciated.
I recently bought a 2006 2500hd with the 6.0l and a 4l80e knowing that it had tranny issues. When I first scanned the truck it had a pending code of p0894 indicating that there was component slipping. Around town it was fine with no real symptoms at all but the truck had a harsh 1-2 shift with all other shifts being really firm after driving on the highway.
After looking through many service bulletins and other resources, as well as talking to a couple different transmission shops, the general idea was that the converter was most likely the cause and that the piston ended up cracking inside. So I ordered up a Precision of New Hampton converter along with a TCC regulator solenoid.
I installed both the converter, solenoid, and a new seal at the pump. Along with a new filter, I flushed the lines with brake clean and shop air (was told that it should be enough if the pan was clean; and the pan was really clean). The filter had some larger chunks of clutch material in it. Fluid level was correct.
I took the truck for a drive (20 minutes) and it felt great around town but once on the highway it was shifting even harder than before and the temp gauge was around 190 degrees F. I parked the truck and made a couple of phone calls to some shops around town as well as a dealer tech who said that it might just need to relearn the shift pressures and that I should clear any pending codes (P0894).
So I cleared the codes and took the truck for a second drive (20-25 minutes). The results where the same; good in town but getting hot on the highway and harsh shifting. I was on my way home and the gauge was at about 220 degrees F at which point the truck started to slip in drive and even reverse. So I instantly shut it down and waited for it to cool off. Once cold the truck wasn't slipping or anything and shifted good.
I pressure tested it and all of the numbers were within spec when I controlled the current to the EPC motor. The pump will produce about 177psi at 0.02 amps to the motor. When in park I have 60psi, R-90psi, N-60psi, D-55psi, 3-55, 2-between 40 and 55psi, 1-50psi (all of these pressures are static with the park brake on). GM states that drive, park, and N should be between 35-171psi with reverse being 67-324psi.
I dropped the pan again and found a large amount of VERY fine clutch material with no big chunks like I found in the filter the first time. Fluid was burnt. I also found to my horror that the TCC PWM solenoid was pushed out a ways and when I removed it that the most inward o-ring was over the screen on the solenoid where 2-3 fluid is supplied. I believe the clip was not seated on the correct part of the solenoid and I am kicking myself for that now.
I proceeded to drop the valve body to make sure nothing was stuck in any of the bores. Both of the filter screens (EPC and the TC one in the case) were ripped open. All of the valves moved freely in the bores and there was no major debris in it.
I bought a new valve body anyways thinking that it might be a good idea at 160,000 miles on the one that was in there. I had both the rad and the external cooler professionally hot tanked then I flushed them after with Dr. Tranny Kooler Kleen.
I installed the new valve body and put a massive in line filter (30" reverse osmosis high flow filter) before the coolers to catch anything that was still in the converter before going into my now clean coolers.
The new VB was installed with GM gaskets and a GM filter. Dex VI was used and I took it for another drive with the scanner (snap-on Solus) and pressure gauge still installed. Pressures looked good driving down the road but P1870 count was at 2 before hitting the highway and in 4th gear at lockup I had between 180-380 rpm of slip with TP at about 10-30% cruising.
It shifted closer to my initial drive before I even touched the truck after going on the highway and check engine light came on. Transmission temp was drastically lower at about 110-150 degrees F.
I have yet to drop the pan again and have a theory that it would have been better if the solenoid fell right out. I think I have glazed the TCC because of the solenoid but I am looking for other ideas of what else I should check before I burn up another converter. I read on bulletin #08-07-30-008B that the converter clutch valve in the pump must have a travel of 13mm, how is that checked?
Also I am worried about the cause of the truck slipping in all gears even reverse. I know that some material might have got into the old EPC motor because of the ripped screens and blocked a passage (why I changed out the VB) but is there any other things I should consider? My other thought was that it might have got hot enough to try and lock the TCC in order to try and cool it off but if it was just leaking past the solenoid it wouldn't have helped and just might have slipped at the locked TCC.
I have come to terms with the fact that I most likely screwed the current TC but don't want to screw another one.
Any help would be greatly appreciated! I am currently out of ideas and I think in need of some fresh insight.
Thanks for reading, I know it was long
03-30-2016, 07:41 PM
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p0894 Hey bud,Im not even sure you will get this message being its been a few yrs since your post on the tranny issue you had with the p0894 code.I have the same exact issue,I replaced the TCC solenoid,that didn't help,Im thinking either the torque converter or valve body,as everything else is fine with the tranny,no slipping in reverse or 1-3 gears,no burnt fluid or massive metal on the magnet.Im wondering what resolved your issue,the torque converter or the valve body?
