Replying here instead of the PM:
You have two parts to the ignition. The tumblers that the key turns and the switch part at the end of the tumblers. Inside this switch are several isolated circuits. You could have the engine run and not have other electrical items operable. Could be a loose wire in the plug to the switch or could be the contacts inside the switch.
Pelican has the early 944 electrical diagrams here:
http://www.pelicanparts.com/944/electrical/944_electrical_diagrams.htm
You want to look at this one:
http://www.pelicanparts.com/944/electrical/944_84_4_1.jpg
and this one:
http://www.pelicanparts.com/944/electrical/944_84_4_2.jpg
Print them out and tape them together. Actually capture all of the images and print them out. The Haynes manual for the 944 has basically the same diagrams.
Another point that you may be having problems with is the positive terminal on the battery. Many older 944's have had the end cut off and an aftermarket terminal attached. These need to be taken apart periodically and cleaned. The several 10 gauge wires coming off of it provide power to other parts of the cars electrical.