How to tell if TC has lock-up?

[VAL]

Does anyone know how to tell, if a TC is lock-up or non lock-up, with the tranny still in the truck? Its a 700r4.

 

[da_raabi]

Good question. I was just trying to figure out the same thing on my T400.

 

[SlickGTP]

The TH400's never had a lock up converter. If I remember right all 700r4's had lock up converters. The TH350's are the ones you have to watch out for as some had a lock up converter in the later years.

 

[Jims86]

The TH400's never had a lock up converter. If I remember right all 700r4's had lock up converters. The TH350's are the ones you have to watch out for as some had a lock up converter in the later years.

Get above 40 mph in OD, then press the brake pedal with the left foot to see if the engine rpms go up.
I have never seen a 700r4 without lockup, unless it was a full out racing application. My testing method may not work if there is an electrical problem, or faulty Lockup solenoid.