[506wabash]

Are there any signs or way of telling when a converter is locked up? Like can you tell on the tach, etc...?

 

[Detroit Gearbox]

Trained eye can catch it on a tach. Accelerate slightly when you think its locked.... if rpms do not rise its locked up.
Also steady speed slight acceleration lightly depress the brake petal & see if rpms jump 3-400 rpm. It should jump... although if the clutch slips more than 200 rpm it will throw a dtc.
Most scan tools show rpm of tcc slipage.

 

[fastvette]

You can try and press the brake pedal, watch the rpm. I think also while driving, tap the pedal.

 

[forcd02]

Tach, feel, brake pedal, etc-if a loose converter, you will def feel it
Its usually around 200 RPM, maybe less on a tight factory converter, esp flat ground, downhill

 

[fastvette]

I might mention that in a '96 chevy w/ 4l60, I am up to speed about 60-70 mph, tap the brake there is to be a small rise on rpm. Then let off the brake, rpm drops and it's normal. That's how I understand it.