1996 960 automatic - unusual torque converter lock up

[V-Jet]

Hi,

Having a very unusual problem with the AW30-43 transmission on my 960 wagon. When shifting between 1st-2nd as well as 2nd-3rd the torque converter locks for a split second then unlocks. When it locks the engine RPM drops noticeably but recovers when it unlocks. Transmission has just been professionally rebuilt & lock-up solenoid replaced, yet the problem is still there.

I have a diagnostic tool that displays live data from the TCM (transmission control module), this showed me the lock-up relay was briefly engaging then disengaging during gear shifts. This was my "ah ha!" moment until I also did a diagnostic live data readout of my two S90's and saw both cars do that as well, so it seems to me that it is supposed to do that. Yet my S90's gearbox shifts very smoothly, it's only on my 960 wagon that I noticeably feel the torque converter locking briefly during gear shifts.

Today I swapped the TCM to confirm that it's not caused by a faulty TCM. I couldn't find a 2.5 TCM so I fitted a 3.0 TCM temporarily know that they are different. Initially the fault was still there, confirming that the original TCM is not faulty, but after a while the 3.0 TCM had a disagreement with the 2.5 gearbox & threw the "AT-341 Lock-up function slipping or not engaged" code which in turn disabled the lock-up solenoid. Interestingly after that my gearbox shifts smoothly, so at least I can confidently say the fault lies somewhere within torque converter lock-up, but not the solenoid.

Any suggestions to what might be causing this very unusual fault?

[93Regina]

AW30-43 transmission on my 960 wagon.

Myself, I'd be cleaning all electrical connections to that tranny, ohm spec relevant sensors, do a pressure test, and sift thru this document.

Volvo: Automatic transmission AW30-43 le AW30-40/43LE AW30-40/43 le AW30-40 le

Hey, around 4 grand can buy a rebuilt/new with a torque converter....

[17yearsofboost]

Does the AW30-43 use the same solenoids as the Aisin 30-40LE transmission? Where did you source the new SL lock up solenoid I can't find one anywhere? NLA part # 3515644??

[lummert]

Aisin Warner P/N: 99 03 740 041 from Greenbook. Don't have a clue about availability.

[17yearsofboost]

Yes that's it!! What is Greenbook? Unfortunately that part # is no longer available anywhere. How did V-jet source one for his rebuild 2 or 3 months ago???

[__Lloyd__]

I have a 1996 Volvo 850 and while I do not have all the tools....I have figured out that for some reason the torque converter " IS " locking up for a brief moment when shifting from 1st to 2nd and from 2nd to 3rd as well. HOWEVER....once the engine and trans is fully heated up it runs nice and shifts like it should. Other things are....if your rolling slowly like 10 to 15 Km/h and you press the WINTER button for the trans...the converter locks up so bad that the engine stalls. Feels just like as if you are driving a standard trans and you shift from 1st to 5th and dump the clutch. Sometimes it stalls RPMS drop super low....engine under heavy load then the converter UNLOCKS its self...and all is fine.

Sometimes when cold or not fully warmed up it does the lock up thing DOWN shifting as well....whole car rattles from over loaded engine...again for a brief moment the RPMS drop so very low that it almost stalls the engine....like 300 RPMs that how low.

Trans is healthy from what I can tell NO codes from it....oil is nice pink / red and has no bad smell...smells like it just come out of the bottle like new. Trans oil was changed twice...and the trans has been also flushed once, and yet I still have this problem. As I said it seems to be clearly a momentary Torque Converter lock up when shifting at very low speeds...1st to 2nd....then 2nd to 3rd....I do not feel it when going from 3rd to 4th...and at 80 KM/H the converter locks up as it should normally and so on. What is the cause of this...and HOW can I fix this...???