2007 Buick Lucerne 4T65E

[LT 33]

Four weeks ago, transmission serviced at 56,700 miles with STP fluid and AC Delco filter.
Next day experienced intermittent long 1-2 shifts, at times revving between shift, 2nd
gear starts, and later at highway speeds TC failure to lock up.
GM transmission tech advised to disconnect battery for 8 hours to accomplish adaptive
relearn which would take 50 key cycles.
After doing this twice, car now has 2nd gear starts, trans operates normally otherwise.
GM shop diagnosed and came up with: Shift solenoids commanded states are correct;
TC clutch operation OK; still 2nd gear starts....Possible causes: 1-2 solenoid bleeding
pressure; stuck 1-2 shift valve in body, need to test solenoid and R&R valve body and inspect.
Your thoughts??

 

[Trav]

That sounds like a heck of a coincidence. I would check the obvious like the fluid level if okay drop the pan and look for an incorrect filter or more likely a filter not fully seated or a damaged filter seal. At 56K this should not be happening, do not drive this car before getting it checked out you could be damaging the transmission.

 

[ripcord]

^^^ Big plus one on what Trav is telling you.

 

[Fordiesel69]

Please top driving it ASAP. Something is not right.

STP makes an excellent fluid that is OEM licensed. I use their mercon V and their ATF+4 frequently.

I do not own GM vehicles so I cannot speak about their Dexron lubricants but assume they are just as good.

Re check all of their work.

Also a battery drain may not be enought, you may need a scanner to reset the values or you may need to go into a learning mode like on the ZF 8 speeds.

 

[LT 33]

That sounds like a heck of a coincidence. I would check the obvious like the fluid level if okay drop the pan and look for an incorrect filter or more likely a filter not fully seated or a damaged filter seal. At 56K this should not be happening, do not drive this car before getting it checked out you could be damaging the transmission.

Thank you, the original shop is installing a new seal on Wednesday, fingers crossed..

 

[blufeb95]

I do not own GM vehicles so I cannot speak about their Dexron lubricants but assume they are just as good.

4speed GM transmissions tend to be some of the least picky about fluid, any dex/merc, dex VI or universal ATF should work just fine.

 

[clinebarger]

If the 1-2 shift valve was stuck or Solenoid A was leaking.....You would have no 3-4 shift.

I'd also expect a Solenoid A performance DTC.

 

[LT 33]

If the 1-2 shift valve was stuck or Solenoid A was leaking.....You would have no 3-4 shift.

I'd also expect a Solenoid A performance DTC.

Thank you, sir....!

 

[LT 33]

Local shop did a second trans service this AM with new filter and seal...I did 20 stop and starts and 1st gear came back on about half of those, and I was able to downshift to 1st half of the time.....Spoke to the GM tech (small town, both close to each other) and he still wants to pull the side cover and bench test the 1-2 solenoid (he still believes it may be bleeding pressure) and still wants to check the 1-2 valve for sticking.......$180/hour labor......

 

[ripcord]

If you have him going into the valvebody, the general advice is to replace the pressure control solenoid while he's in there. They are a common cause of erratic shifting.

 

[Trav]

Local shop did a second trans service this AM with new filter and seal...I did 20 stop and starts and 1st gear came back on about half of those, and I was able to downshift to 1st half of the time.....Spoke to the GM tech (small town, both close to each other) and he still wants to pull the side cover and bench test the 1-2 solenoid (he still believes it may be bleeding pressure) and still wants to check the 1-2 valve for sticking.......$180/hour labor......

Check the fluid level yourself, when you drop the filter on these quite a bit of additional fluid comes out. engine at operating temp, level ground.

 

[LT 33]

10-4!

 

[LT 33]

If you have him going into the valvebody, the general advice is to replace the pressure control solenoid while he's in there. They are a common cause of erratic shifting.

If you have him going into the valvebody, the general advice is to replace the pressure control solenoid while he's in there. They are a common cause of erratic shifting.

Was thinking all four solenoids and the MPS
Independent transmission shop told me most replacement solenoids made these days are poor quality......