Starting a day or so ago my converter stopped locking up in my daily which has a 4L60e in it, or so I thought.

As I test I decided to hook up my HP Tuners and try locking up the converter with it @ 70 mph. Seemed to notice a slight change in RPM but couldn't be sure...

So I checked @ idle knowing that if I lock up the converter it will stall and die. Well my driveway is steep, truck was sitting still in D and when I locked up the converter the motor changed tone then started up the incline. Turned off the lockup and the truck stopped moving. Tried this several times...

So it seems the PCM is commanding lockup, the solenoid is enabling lockup, but the converter is slipping during lockup.

Fluid is clean off the dipstick and the truck drives 100% normal other then that, zero shutter even and no codes.

My guess is the converters lockup clutches are wore out???

Regardless I have a Circle D 278 mm 3200 on the way to replace my Edge 245 mm 2600, converters lockup surface was to small IMO anyway and prevented me from towing.

Also for a note, a week before, my tuner made the mistake locking the converter @ WOT. This happened on several pulls, thought it was a shifting issues till I looked @ the tune... *face palm* may be to blame.

Any input or incite on this would be helpful. Have searched and searched to no avail.

Thanks

Jay