1993 Maxima Error code 21? HELP!

the '93 Maxima I'm working on has no injector pulse on cranking, it sparks fine, and will start with some cranking on starter fluid, but not on its own, Once it starts with the fluid it will run, a little rough, but it'll run, and start again. Until its cold.
The scanner is picking up Error Code 21. I need a wiring diagram so I can find the injector trigger wire. Any help/info would be greatly appreciated.