Could someone explain to me what it means when the torque convertor is "locked out" and how this relates to tow haul mode?

thanks, I'm lame on this one

wally b

Not sure what you mean by locked out, but when the torque converter is unlocked it is sending power through fluid coupling only. Which means it can slip.

I think you mean "locked up". This means that there is a physical connection between the input and output shafts of the torque convertor, similar to a standard clutch when engaged.

When locked-up, the engine output is "essentially" connected directly to the transmission input (ie. no fluid coupling). When towing, you want the torque converter locked up, otherwise you could possibly overhead the transmission fluid (in other words, if the torque converter is "un-locked, the engine output is transferred to the transmission via fluid coupling, this coupling is not 100% efficient and some of the inefficiency generates heat). When using the tow haul mode, the Transmission computer locks-up the torque converter in gears 2-5, thus minimizing the temperature rise in the transmission fluid.