1998 Dakota, override shutdown problem

[Mistress]

Hi there,
It's my first post on the forums. I just don't have time this afternoon to find the place where I'm supposed to go and introduce myself ( sorry guys! ).
I'm here to hopefully find some advice for a friend.
He was driving along. Everything was fine. Then the motor shut off like someone turned the key off. There was something that told him it was an override shutdown, a light on the dash or something. There is no fire to the sparkplugs. The fuel pump does not seem to be working at all. It makes no noise.
Anyway, to cover some of the things that may cause the override shutdown, (so I am told)... the crankcase oil level is fine. The truck was not running hot. Radiator coolant level is fine. The gas tank was half full.

He took a voltage tester and checked the fuse box fuses for continuity. They are all fine.
He has a code reader for it, yes, obd II, but when hooking it up to try to read any codes, the code reader is telling him, link error, and try as he might, he can't solve that problem so that he can read any codes.
He has called some mechanics, one said the problem may be in a fusible link or a relay somewhere, or maybe in the computer.
The distributor seems to be fine.
Is there a way to check out relays to see if they are fine (about all he has is a voltage tester), and if so, does anyone have advice on where to start checking?
Anyone have advice on what to do so that he might be able to get access to read the codes? He said that his code reader and its contacts should be making contact where he plugs it in.
This is all I know right now.
Any advice would be very much appreciated

I have to run off for now but I hope to be able to check this sometime tomorrow.
Be good.