I just bought a 97 F150 4.2 automatic. This is the first automatic I've owned and I'd like to understand how, when and why a lock-up TC works. Please explain in terms a long time clutch pedal pushing person would understand. Any takers?

 

This gives a good overview on how they work.

http://auto.howstuffworks.com/torque-converter.htm

 

Thanks for replying jimk-nj, that did the job. the only other question I have is, how can you tell when the converter locks up and around what speed would my trucks TC lock-up.

 

Well every truck is different. Lockup occurs between 37-50mph in most cases you will usually see about a 200rpm drop when it happens.
Alan

 

Hi.

Since the PCM commands lockup via an output to the TC lockup solenoid, you can wire up an indicator to that signal - more blinky lights ya don't need ( I can't seem to get enough of 'em ;-)). Model year specific pinouts.

Cheers

 

The internet's a wonderful thing. I've learned more from you guy's that reply to my post in a day, than I could in a year's worth of trial and error. Unfortunately I don't have a tach, but I'm going to add it to my list. I'm looking into piller mounted gauges, including oil pressure, trans and water temp and maybe some blinky lights.
Thanks guy's, your a big help.