Here' the quick and easy chech for your ingnition switch
( from '89 vol 2 FSM , sec. 8 , page 152).
.
Disconnect terminal, black plug is the switch, white is hot.
Turn key to "on" position.
Insided black switch plug connect your ohm meter to the Black/white wire's terminal and to the black wire's terminal. These are ingnition connection inside the switch.
Also check B/W to Blue. This is accesory wire to fuse box and is also connected when switch is in on position.
I would use alligator clips so you can wiggle the key and wiggle the harness near the switch to check for a intermitant situation.
If your switch is bad it can be removed by taking out just one little screw on the bottom of the switch.
I got mine at NAPA.

dave h.
'89 Raider V6 5spd;Aisin Hubs;; Gen2 LS: frt. brakes, rear coils;U.C.arms;R.trailing arms;idler arm; rear LSD axle w.disc brakes ;2 battery system for Dog's fan; relocated ECU; custom bumpers;J.Baker receiver;Conferr roofrack; t-bar crank.