When does the torque converter lock up?

[eddeeeee]

I have a new, 2008 Sequoia with the 5.7L engine and the 6sp transmission. I tried posting this on the Sequoia forum, but didn't get a definite answer, so I thought I would try here, as there are many more Tundra owners. Anyway, I was wondering at what gears the Torque Converter will lock. One salesman said it locks in all gears, another said it stays locked ( lol ) and the delivery person said nobody ever asked that question. Does anyone hear know what gears it locks in? Will it lock in any gears when using the sequential shift?

[Canadian_Yoda]

Check in This Thread. There is a PDF that ought to answer your question.

But as I recall, it can lock in 4th 5th or 6th.

[Only Toyota for me]

I've noticed that it locks up in S-4 and will not unlock even when you put the throttle down a little bit (unless you're going slow). It will simply shift down to 3rd.
While in S-5 it will lock up, but will unlock at certain speeds (74mph is the fastest)with a little extra throttle. When i say unlock, i mean a moderate downshift with a 2-300 rpm gain on the tach.
The answer to your question i guess, is the T-C does lock up in gears 4-6 at cruising speeds. Providing no additional throttle pressure is needed.
While in S-5 or S-6 you apply throttle pressure, the T-C will unlock giving you an additional 300 r's before shifting down a gear. But at cruising speeds in S-4, the T-C will not unlock and simply drop to 3rd with enough throttle pressure.

Example: Driving at 70mph on the freeway at 2000 rpm's with the cruise set, you come to a slight incline. The cruise put's more throttle down & you will feel a half shift sort-of-speak (T-C unlock) before dropping to 5th, thus gaining you about 300 r's on the tach putting you at about 2300. If it's a good incline, it will then drop to 5th T-C unlocked and the computer will feel that 5th will do the trick on the hill & will then unlock pulling the rest of the hill in 5th T-C unlocked until it senses deceleration & will then shift back to 6th.

Does this help at all, or just confuse you?

[jkd]

According to the excellent tech/review Trailer Life did on the Tundra: "The AB60 utilizes a ultra-low 3.3:1 first gear to get things moving quickly, and features a torque converter with a lockup in 4th, 5th, and 6th gears. In addition, the converter is equipped with a "flex" lockup function for these gears that allows the converter to partially lock up under some conditions." Sometimes I think there was more to learn from that article than the Toyota owner's manual.

[thumbster]

Lock up is only in 4th, 5th and 6th gear with throttle application, but can be carried from 4th into 3rd only under deceleration with engine braking. I had a lengthy argument with a previous TS poster on this regarding a dyno run. I had originally verified this with a toyota engineer that was partially responsible for programming the shift logic of the 6 speed transmission. When you turn off the traction control and VSC, it greatly affects the converter lockup in 4th gear. The converter always temporarily unlocks when shifting in and out of any gear.

[RONE]

I'm gonna have to visit wikipedia to learn what lock/unlock means when referring to a torque converter. This truck is my first auto!