I just posted about my recent towing expedition, and thought this warranted another topic. Does our torque converter lock/unlock in 3rd gear and 4th gear? Reason I ask is that when towing in 3rd and accellerating onto the highway, I never felt the converter lockup in 3rd. I paid real close attention on the way home, and never noticed it locking in 4th either, even when I stepped on it a little on the highway in OD, it just accellerated. I was even climbing a long steep hill at one point and thought for sure the truck would kick down into 3rd, but it just kept on pulling in OD, temp stayed below 160.

Is it possible to have had this feature somehow removed for towing sake? Previous owner towed a boat I'm guessing, because the pumking was all sorts of rusty when I got the truck but that was the only rust on it. I get good mileage (16.2 MPG for my weeks worth of in town driving + 180 miles of towing my camp trailer at 70mph on the highway). In 3rd gear, RPMs were hovering around 3k at 70mph. Let me know, thanks!

 

Does it lock up when not towing? At 3k RPM, I would think the RPM is to high to lock up because of your throttle position. Just a thought.

Richard

 

I think I saw it locking in third in the edge panel, when I was with OD off.
But with OD, I never seen it locking in third. It locks in four.

 

I've never felt it lock, I count 4 shift points when driving. In my trailblazer you could feel the converter lockup points, especially when in 3rd and accellerating up a hill. The converter would unlock, RPM would go up, then lock and they would come down. And that was when manually locked in 3rd gear. Is the 4R75 something different? I know it sure runs a whole hell of a lot cooler when towing.....

 

Where's the design engineer? Like picaflor, my Gryphon shows a lock-up symbol in third, but only with the "OD off" activated. Otherwise the only lock-up is in fourth. That should be correct as those are the only two "normal" top gears. The 3rd gear lock-up is much less noticable than 4th as far as "feel" goes. When mine locks in 4th it almost feels like a 5th gear.

I haven't heard of a "lock-up deactivator" before...

 

With overdrive off I can feel it lock and the edge shows its locked in 3rd or 4th gear. I have noticed when manually shifted to 1st or 2nd it feels like the TC is always locked (from a dead stop in 1st or rolling in 2nd). It won't unlock unless there is a hard load put on-..mashed to the floor...

OP..if you get on the highway at cruising speed,keep the throttle steady and lightly touch the break and you should feel the TC unlock.

 

I take this statement back...Just tried it and its not like my old truck..This one stays locked.