Torque Converter unlocking in third?

Hi All:

Recently pulled a trailer for a few hours.

My truck is a standard cab 4x4 with the 2.7 motor and 4 speed auto.

While I physically had the truck shifted in third gear going uphill, the TC would lock and unlock.

Is it true that the TC should only lock and unlock in drive? Or, will the TC lock and unlock in third gear also?

I am trying to understand if I have a transmission issue or the TC will lock and unlock while in third gear.

Thanks.

 

if i remeber correctly... the 4 speed in the 2.7 is the same as the 4speed auto on the v6 on the 1st gen's.

It would only lockup in 3rd if you took it out of OD, which is what you are doing by selecting 3rd.

Not sure if they changed the logic on the second gens.

 

Agree with the above statement ^^^^^

The converter will continue to lock and unlock regardless of 3rd gear or 4th .
Locking and unlocking of the torque converter is managed by the ecm and will fluctuate with engine load/ throttle position .
Got some info here that explains this in more detail
http://www.tacomaworld.com/forum/te...warner-340-series-transmissions-write-up.html
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Sure wish this could somehow be switched off. Good to know my tranny is operating normally.

Thanks for the info guys. Appreciated.

 

locking up is good, keeps trans temps down!

 

Exactly. That is why I wish it would not unlock in third gear.

 

With the transmission in 3rd gear and the converter locked directly to the engine at a 1 to 1 ratio ( direct drive ) , anytime you go up a hill pulling a trailer with a 2.7 liter engine , the ecm will command the torque converter to unlock to give the engine a mechanical advantage over the driving wheels . With this said , I believe the trans is working fine . Sometimes an engine tune up will decrease the amount of unlocking but a supercharger would truly help