PCM wiring help

Hello all, I'm working on my wiring harness and need some help. There is a pin labeled: Ignition Accessory Feed. It connects to a few places. The EGR valve and the diagnostic plug and possibly elsewhere.
Can anyone tell me if I need this to run the engine? What is it for?
This is for an OBD I system from a 94 Jeep Grand Cherokee.
Thanks.