There is a relay but it precedes the switch in the circuit, so if the flash-to-pass function works then the relay is good, and also the wiring, connectors and grounds must be good, so it's virtually certain that the multi-function switch itself is faulty and should be replaced.
The wiring diagram is in the Repair Info section at
www.autozone.com or this link might take you directly to the relevant diagram:
'91 to '93 Escort headlights w/o DRL