Torque Converter Lock Up

[fast86gn]

I don't remember if my truck's torque converter locked up after hitting 4th gear. I just had it tuned and now it doesn't lock up. I had the afm turned off when I sent the ecm/tcm away for tuning. So did it not lock up before, or did turning off the afm disable the lock up?

[2COR517]

It should be locking up. When you're cruising along a straight flat road, with no one behind you, touch the brake pedal with your left foot while keeping your right foot on the gas. Watch the tach. If it jumps up, the TC is unlocking. Which of course means it was locked before. The TC control is so complex on these now, it basically feathers the TC clutch in slowly.