What the trick to starting a car without an automatic transmission attached

Hi guys

I tried starting my truck with the transmission attached, following the threads that say its is possible , but not start.

I Have the starter connected, power supply is good. but nothing.

What's the tick to trick the computer that all is ok down their.

I need to check for oil leaks before I put the tranny back on.

its on a 2002 Suburban 5.3 V8 with a 4l60e

any help would be great

thanks.