Can the PCM fully control a 4L60E in an engine swap, and what wiring or programming does it need?

Yes — on GM computers that support it, the PCM runs the 4L60E. Per Holley's shift-kit instructions, a PCM-controlled 4L60E keeps line pressure, shift points and converter-clutch operation under PCM control.

What the swap needs:

• A matching calibration: the tune must be set up for the 4L60E you're running.
• A two-position brake switch for the converter clutch. Speedway warns that wrong wiring can leave the converter unable to unlock.
• A starter relay: Painless notes the transmission-mounted park/neutral switch can't handle the starter solenoid's current, unless you're using a factory switch on a GM keyed column.
• Park/neutral and reverse lights: on truck 4L60Es these share the switch on the driver's-side shift detent rod.

Crate-engine controllers: Chevrolet Performance sells a pre-programmed 4L60E-family controller (19302405), but it works only with its E67-based engine control systems.

See transmission tuning.

Want to do it yourself? See who tunes it, and how to learn.