Well, I don't think I've been much help.  I'm pretty sure you can read the
code on a '93 with a voltmeter by reading the "sweeps."  If you don't have a
repair manual maybe you can find the instructions online somewhere.
Basically it does some kind of indication that it's reading, then you count
how many times the meter moves--three times would equal 3, then there is a
pause (if I remember correctly), then it moves again a number of times.  On
some later Explorers (not sure if '93 is "later" )you can install a jumper
on the Diagnostic Test terminal (behind the fuse box in the engine
compartment) and read flashes of the CEL.  The jumper wire (according to
Hayne's) goes from the "test  terminal" to pin number 2 of the Diagnostic
Test terminal.  The volmeter goes from the positive battery terminal to pin
4
(STO).  This is for the KOEO test.  When it's done it will display 111.
Then is says to remove the jumper and start over with the engine running
(KOER normal temp).  The first code will be 1/2 of the number of cylinders
(3).  It gets complicated after that involving turning the steering wheel,
stepping on the brakes etc so I suggest getting the full instructions.