Transmission codes and hard shifting

Mike534x

Original poster
Member
Apr 9, 2012
894
So the Trans-go kit has been installed, and the truck has been fantastic for the past 4k miles since then. Well, yesterday after a drive around in the city to take care of some errands. I noticed the truck was acting erratically. 1-2 was a harsh again, and 3-4 could be felt like 1-2. Putting it in D or R results in a harsh shift that slightly lurches the truck forward or back. I left it sitting for a bit, and ran out again to the store and it was shifting fine as it did before without any issues at all like nothing ever happened. Fast forward to today, I'm on the highway driving home from work and the CEL kicks in. I'm about 2 mins from home when I exit the freeway, and pull up to a stop light. Harsh shifting again.

Torque is reading a P0700 as the first, and a P0894 as the second. Tranny fluid still looks nice and red, and fresh. Nothing particle wise on the dipstick either or any kind of burning smell.

Any ideas on what it could be? From what I can see, I still have all gears. It just shifts harshly into each one. Restarting the truck seems to temporarily fix it.

Edit:

I tried searching around various forums as well as here, there seems to be a mention of the Transmission Control Solenoid. From what I'm seeing on the 4L60E wiring diagram in the service manuals, it seems to be part of the wiring harness that runs along the valve body. After doing some searching on RA, it looks like AC Delco makes a replacement (Part # 214-1892).
 
Last edited:

TJBaker57

Member
Aug 16, 2015
2,897
Colorado
So the Trans-go kit has been installed, and the truck has been fantastic for the past 4k miles since then. Well, yesterday after a drive around in the city to take care of some errands. I noticed the truck was acting erratically. 1-2 was a harsh again, and 3-4 could be felt like 1-2. Putting it in D or R results in a harsh shift that slightly lurches the truck forward or back. I left it sitting for a bit, and ran out again to the store and it was shifting fine as it did before without any issues at all like nothing ever happened. Fast forward to today, I'm on the highway driving home from work and the CEL kicks in. I'm about 2 mins from home when I exit the freeway, and pull up to a stop light. Harsh shifting again.

Torque is reading a P0700 as the first, and a P0894 as the second. Tranny fluid still looks nice and red, and fresh. Nothing particle wise on the dipstick either or any kind of burning smell.

Any ideas on what it could be? From what I can see, I still have all gears. It just shifts harshly into each one. Restarting the truck seems to temporarily fix it.

Edit:

I tried searching around various forums as well as here, there seems to be a mention of the Transmission Control Solenoid. From what I'm seeing on the 4L60E wiring diagram in the service manuals, it seems to be part of the wiring harness that runs along the valve body. After doing some searching on RA, it looks like AC Delco makes a replacement (Part # 214-1892).


I don't see a year for your truck in your profile but here is something...

Screenshot_20201126-090228~01.png
 

Mike534x

Original poster
Member
Apr 9, 2012
894
Do you use the Torque Pro app? You could monitor some transmission stuff there to help see what is happening.


I thought it was listed in my profile, but its an 05. I do have Torque convertor pro, I'll just need to look through it again to see how I can monitor the transmission functions.
 

TJBaker57

Member
Aug 16, 2015
2,897
Colorado
I thought it was listed in my profile, but its an 05. I do have Torque convertor pro, I'll just need to look through it again to see how I can monitor the transmission functions.
There are some that are built in to the predefined set for GM. Of course you need to load the predefined set.

One thing that could maybe help is watching the TCC Slip rpm. That seems to be implicated with the P0894 code.

I also monitor the overall gear ratio with a virtual PID by dividing input shaft rpm by output shaft rpm.
 

Mike534x

Original poster
Member
Apr 9, 2012
894
There are some that are built in to the predefined set for GM. Of course you need to load the predefined set.

One thing that could maybe help is watching the TCC Slip rpm. That seems to be implicated with the P0894 code.

I also monitor the overall gear ratio with a virtual PID by dividing input shaft rpm by output shaft rpm.

Working on getting the Torque info, but I noticed the RPMs seem to be off at causing speed. Usually its around 1100-1300 rpm when doing 40 when warmed up but here its happening sooner?
 

Attachments

  • 20201127_180343.jpg
    20201127_180343.jpg
    218.2 KB · Views: 9
Last edited:

TJBaker57

Member
Aug 16, 2015
2,897
Colorado
Working on getting the Torque info, but I noticed the RPMs seem to be off at causing speed. Usually its around 1100-1300 rpm when doing 40 when warmed up but here its happening sooner?

I will have to say I don't understand what you are saying here!
 

Mike534x

Original poster
Member
Apr 9, 2012
894
I will have to say I don't understand what you are saying here!


Poor wording on my part, and recouping from the hangover on Turkey Day! My bad! Usually when doing 35-40, the cruising RPMs usually hover around 1100-1400 RPM but for whatever reason Torque and the Tachometer was showing that it was reporting 850 RPM which doesn't seem right.

I took it for a long drive on the highway, well long enough to get the tranny fully up to operating temp and noticed no issues with acceleration or RPM surging to indicate the Torque Convertor might be an issue or to see if it was locking/unlocking. I think the cruising speed doing 65 MPH with the 3.73 gears is around 1850-1900 RPM, and thats where the needle stayed throughout the drive. Of course, getting off the highway resulted in hard shifts through the gear range again. I did another test earlier, by taking the truck out of "D" and switching manually between 1, 2, and 3 (while stopped at a stop sign) to test if I had all gears, which thankfully I do. Monitoring the tach and torque, I could see there were no flares present between each gear change with it out of OD nor were there any signs of slippage either. Which is having me question if its something within the valve body setting off this code.
 

TJBaker57

Member
Aug 16, 2015
2,897
Colorado
I think when you have those codes you reported earlier active in the PCM the behaviour and operation of the transmission is altered. I think I read that the line pressure is increased and some other changes as well but of course now I cannot find the document.

TCC Slip rpm is absolutely something that needs monitoring here.
 

Mike534x

Original poster
Member
Apr 9, 2012
894
I think when you have those codes you reported earlier active in the PCM the behaviour and operation of the transmission is altered. I think I read that the line pressure is increased and some other changes as well but of course now I cannot find the document.

TCC Slip rpm is absolutely something that needs monitoring here.

I dropped it off this morning to a tranny shop thats highly recommended around here. They cleared the codes, and took it for a test drive. The scan tool is reporting a 100 rpm fluctuation, with the tranny going into high line pressure mode doing 50 MPH down a stretch of a road. I forgot what the shop owner said exactly, but its showing TCC engagement at 97%.
 

Mike534x

Original poster
Member
Apr 9, 2012
894
Update:

Dropped the Envoy off yesterday to the tranny shop, since it was going to take about a week to get it in. I convinced them to pull the VB and check everything again, they ended up reeming the TCC valve bore and replacing the Trans Go one with the slightly bigger version from Sonnax. So far, everything seems perfect! They drove it for a bit earlier, scanner was showing everything within operating range.

TC is kicking in when its supposed to, and still feels like a 5th gear which is extremely nice. The slightly harsh 1-2 shift is now for the most part completely gone, it feels just slightly firmer over what it was from stock.


I'm taking her during the Summer for a full rebuild, it was quoted as $1,750 with a 18k/18 month warranty. The shop comes highly recommended around here, and the owner seemed pretty chill. When the time comes, I'm going to look into having them put in the corvette servo, and the Sonnax Super Hold for the 4th gear to get the most out of it. The second shop I took it too wanted $2,500, which seemed outrageous when they wouldn't even include the cost of doing the rear main. :no:


Edit: Fixed spelling/added more to the update.
 
Last edited:

Forum Statistics

Threads
23,273
Posts
637,498
Members
18,472
Latest member
MissCrutcher

Members Online

No members online now.