Torque Converter won't unlock coming to a stop

[2000StreetRod]

DTCs?

It's a shame that after replacing so many parts that you're still having problems. Do you have any DTCs? Does the O/D light flash? Is the ATF level correct?

The 5R55E has an internal thermostat that opens the external ATF cooling loop when the torque converter temperature reaches 150 degrees. If the transmission shifts normally when cold but poorly when warm that may be an indication of low line pressure.

The following may help isolate to a transmission internal problem:

On the 5R55E transmission range selector position "2" is actually 3rd gear. The intermediate band, forward clutch and coast clutch are applied. SS1, SS2 & SS4 are On. There should be engine braking.

When manual 1st is selected the low/reverse band, forward clutch and coast clutch are applied. SS1 & SS4 are On. There should be engine braking.

When Reverse is selected the low/reverse band and direct clutch are applied. SS1 is On. There is no engine braking.

It can be difficult to isolate between a transmission fault and an engine performance fault causing the PCM to enter "limp mode". If the PCM detects a transmission fault it frequently flashes the O/D light.

 

[Spokanedad]

It would appear that you have an engine problem and a trans problem, the code you pulled is for the engine, you didn't post a transmission code? The code reader that you used probably couldn't read Manufacture transmission DTC codes, not all OBD2 readers can. But you have cleared the codes and in order to pull a trans code the OD light needs to have flashed, then a code for the trans is stored.

No OD flashing light at all.... The 0320 code I have been attempting to cure was pulled by the tranny shop. No transmission codes at all.. The engine seems to be running fine... The transmission stalls out anytime I put it in "D" or even if I shift down from "D" to "2".. However, if I start out in 2nd it won't stall but feels sluggish. I can also shift to "1" and it will go as well. Reverse doesn't seem to have been affected. So far.

Baffled..

 

[Spokanedad]

Towed into the tranny shop today... Condition when it went in was almost complete failure of TQ converter. 1st gear was gone unless manually shifted to "1".. If put into drive it would stubble to hold 3 and 4th, bouncing around between. Wouldn't unlock and will stall at full stop.

Shop called (very reputable). And told me the TQ converter was definitely cooked. There was pieces of metal in the pan. They will be taking it apart and will be letting me know what they find inside.

I am posting this because others may find there own symptoms in this thread... At least I eliminated the possible electrical possibilities before going inside.

 

[Spokanedad]

Towed into the tranny shop today... Condition when it went in was almost complete failure of TQ converter. 1st gear was gone unless manually shifted to "1".. If put into drive it would stubble to hold 3 and 4th, bouncing around between. Wouldn't unlock and will stall at full stop.

Shop called (very reputable). And told me the TQ converter was definitely cooked. There was pieces of metal in the pan. They will be taking it apart and will be letting me know what they find inside.

I am posting this because others may find there own symptoms in this thread... At least I eliminated the possible electrical possibilities before going inside.

***update***
Tranny overhauled. Internals replaced: TQ convertor, forward clutches, intermediate band, seals, o rings and gaskets. Truck up and running. Lesson learned, sometimes the electronic component isn't the root cause of tranny issues but at least if you have to take it to a shop for repair, eliminating those items from the possibilities puts you in a much stronger position with the repair than leaving it to chance.

Next up: fixing the timing chain rattle and peeling paint on the roof... Woo hoo!

Thanks for all the help I received here trying to eliminate all of the tier one issues/possibilities!