4L80E Hard 1-2 Shift

P

Peteco

Joined
Oct 2, 2009
Messages
73
Location
VA
Vehicle: 2006 Chevy Express 3500, 6.0 engine, 4L80E transmission

About a year ago I experienced a hard clunk shift from 1st-2nd gear. This happened several times during a 10 minute drive. No DTC code. After stopping the engine and restarting it has shifted fine ever since. Local transmission shop hooked up Snapon scanner and it showed no codes. Drove vehicle and it shifted smoothly through all 4 gears. Scanner showed no codes. Showed no slippage in 4th gear, indicating TCC was activated and holding.

Yesterday the check engine light (DTC) was on when my wife picked me up. I drove the van and it would hard shift again 1st-2nd just like a year ago. Stopped at OReilly’s and read the DTC: P0894 Transmission Component Slipping. Drove home and in the morning I cleared the DTC and it shifted fine for a few miles. Then the hard 1-2 shift returned, but with no check engine light.

One other odd thing: it seems to be using more fuel recently. So I'm wondering if the TPS is going bad, which I think can cause a hard 1-2 shift??? But there is no TPS related DTC.

Other than the hard 1-2 shift, and possibly worse fuel mileage, the transmission seems to shift fine.

Relatively simple things to do: install TransGo 4L80E-TCC regulator valve (or the Sonnax), new TCC solenoid and possibly the harness? Anything more difficult than this will have to be done by transmission shop.

I’m 1200 miles (and 1 month) from home right now. Do I need to get this fixed right away or can I “baby” it until I get home?
 
Wasn't the a GM product where a failing MAF would throw things all out of whack for the transmission up to and including them burning down?

IE The MF failed and the trans went to full pressure all the time.
 
I hate to suggest a parts cannon approach, but if the snap on scannner didn’t offer you any insight there isn’t much to go on. Considering the cost and ease of replacement, I think it is worth replacing the TPS. A long time ago I chased shifting problems on a transmission that ended up being solved with a new TPS.

Other possibilities include a faulty shift solenoid, faulty accumulator, etc. Did the transmission shop you visited have any ideas?

Last summer I installed a “shift correction kit” in the 4L80E in my Suburban and it has never shifted so good. If you end up having to go inside the transmission for a deeper inspection I would install one of these kits while you are in there.. The kit I used is made by Superior.
 
Rob_Roy said:
I hate to suggest a parts cannon approach, but if the snap on scannner didn’t offer you any insight there isn’t much to go on. Considering the cost and ease of replacement, I think it is worth replacing the TPS. A long time ago I chased shifting problems on a transmission that ended up being solved with a new TPS.

Other possibilities include a faulty shift solenoid, faulty accumulator, etc. Did the transmission shop you visited have any ideas?

Last summer I installed a “shift correction kit” in the 4L80E in my Suburban and it has never shifted so good. If you end up having to go inside the transmission for a deeper inspection I would install one of these kits while you are in there.. The kit I used is made by Superior.
Click to expand...
I don’t normally do the parts cannon approach but for $60 I will change the TPS (AC Delco part).
 
The TPS on these is the entire TB really, not just the sensor.....aint no 60 bucks.
 
Peteco said:
Throttle by wire started in 2007 for the Express vans.
Click to expand...
well there it is, thanks

i wonder why in the vans but not in the trucks?

I have had a 2001, 2004, 2003, 2006 suburban, and several truck of the same years, all by wire.
 
burbguy82 said:
well there it is, thanks

i wonder why in the vans but not in the trucks?

I have had a 2001, 2004, 2003, 2006 suburban, and several truck of the same years, all by wire.
Click to expand...
the vans lagged behind the full size trucks/suv’s by quite a bit. silverado’s didn’t go DBW until 03.
 
Replaced throttle position sensor. It needed replacing as the internal return spring had failed. Tranny shifted fine for 60 miles. Then hard shift returned. Then 20 minutes later P0894 code was set.

Clinebarger, please advise if you see this.
 
P0894 is causing the hard shift, It's a "2-trip" DTC, Meaning it will not light the MIL lamp until the next key cycle with the same fault.

I've seen federal emissions vans not trip the MIL at all....Just stores the P0894, Still goes full line pressure & inhibits lock up.

Either the Converter Clutch is slipping/not applying or the 4th Clutch is slipping (The PCM cannot differentiate), My money would be on the TCC.

How many miles on on this rig?
 
clinebarger said:
P0894 is causing the hard shift, It's a "2-trip" DTC, Meaning it will not light the MIL lamp until the next key cycle with the same fault.

I've seen federal emissions vans not trip the MIL at all....Just stores the P0894, Still goes full line pressure & inhibits lock up.

Either the Converter Clutch is slipping/not applying or the 4th Clutch is slipping (The PCM cannot differentiate), My money would be on the TCC.

How many miles on on this rig?
Click to expand...
160,000. A year ago it did the same hard shift on one key cycle. After stopping and restarting there was no hard shift. The light never came on.
 
Maxlife and Lubegard red helped fix my 1/2 harsh shift in my 4l60, could also add a tube or 2 of Lubegard Shudder Fixx instead of the Red. I'd try that route.
Peteco said:
Vehicle: 2006 Chevy Express 3500, 6.0 engine, 4L80E transmission

About a year ago I experienced a hard clunk shift from 1st-2nd gear. This happened several times during a 10 minute drive. No DTC code. After stopping the engine and restarting it has shifted fine ever since. Local transmission shop hooked up Snapon scanner and it showed no codes. Drove vehicle and it shifted smoothly through all 4 gears. Scanner showed no codes. Showed no slippage in 4th gear, indicating TCC was activated and holding.

Yesterday the check engine light (DTC) was on when my wife picked me up. I drove the van and it would hard shift again 1st-2nd just like a year ago. Stopped at OReilly’s and read the DTC: P0894 Transmission Component Slipping. Drove home and in the morning I cleared the DTC and it shifted fine for a few miles. Then the hard 1-2 shift returned, but with no check engine light.

One other odd thing: it seems to be using more fuel recently. So I'm wondering if the TPS is going bad, which I think can cause a hard 1-2 shift??? But there is no TPS related DTC.

Other than the hard 1-2 shift, and possibly worse fuel mileage, the transmission seems to shift fine.

Relatively simple things to do: install TransGo 4L80E-TCC regulator valve (or the Sonnax), new TCC solenoid and possibly the harness? Anything more difficult than this will have to be done by transmission shop.

I’m 1200 miles (and 1 month) from home right now. Do I need to get this fixed right away or can I “baby” it until I get home?
Click to expand...
 
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