I also bought AAA towing when I had intermittent problem with a 94 grand cherokee,,

 

My car is automatic. I will take all the dash apart this weekend to see if I can trace the wires.

 

,could be icu,but acts like intermittent short in wiring, any luck yet

 

Last weekend I changed the original cylinder lock and the switch and replaced all those components. Looked at the wires until they disappeared into the harness.
I bought this part which comes with the housing.
68020927AA - Genuine Mopar Switch-Ignition
I also coded a new ignition cylinder from dorman.

I reasoned that if it was due to the ignition switch and I had already tried 2 different ones, then it could be that the housing that moves the switch was out of spec due to use, and was maybe causing the switch to misbehave.
It has worked for 2 days so far, lets see.
The first time I changed the switch, it lasted a month without problems, and when I put the other switch in, it was a week before it blew the fuse.

Thanks for asking, have a good one.

 

Where were the possibly defective switches and the last one purchased,thanks john

 

I got the first switch in O'Reilly. After the fuse blew, I took it back and they gave me a new one.
The last one that I bought, complete with housing, was an OEM part. Hopefully, all works fine with this one.