I thought it might help to explain a little more.
If your car has been in a wreck,there likely is a problem with wiring passing through body panels. You'd want to find and check splices, you might find that the wiring is spliced together in odd places.
If car has not been in a wreck, it may have been flooded and the BCM, which is under the drivers seat, probably got wet and is now failing.
If you have a factory manual the trouble charts and diagrams will be invaluable to figure out how to fix whatever.
There are a bunch of wires running through the ignition switch (so not confuse it with the ignition cylinder, which has one wire). If your problems started after that new switch was installed, you need to find out if it was really new, if it was indeed a Riv switch (other GM switches fit and plug in BUT are wired differently I am told), and if the wires were routed correctly and secured when installed (if not they chafe and short out).
The foregoing should help explain why I asked all those questions.