Electrical issues HELP needed

The following list of new onset electrical symptoms that I cannot find the source for:
Non-functional instrument panel analog and idiot light gauges, no turn signals or radio but still have head lights, tail lights and 4 way flashers.
All fuses good, idles intermittently rough.
ECM issue? Short behind instrument panel? What do I need to do to find the culprit!

 

First, you need an FSM. There are FSM's available on several forum sites, in PDF format.
Just a note: Be aware that the wiring would change, not only year to year, but even within a year. Like the wiring of an 88 built in March could be different than the wiring for an 88 built in November. Just something to be aware of so you don't get stuck in the wire color or fuse designation rabbit hole.

I may well be wrong, but it sounds to me as though you have an intermittent open in a main power wire feeding the fuse panel under the driver's kick panel. All the fuses may read good, but what about the wires that feed the fuses? I would check the voltage on the main power wire feeding the fuse block. Also, there is a very important ground point right above the fuse block. There are 4 wires all crimped together, but they have a habit of coming loose inside the crimp. See what happens when you give each wire a little tug with a pair of needle-nose pliers.

The secret is to make certain you wiggle the wires and cables as you check them. Easy to a wire to break inside the insulation. LOOKS totally fine, and be making contact, sometimes, but when you hit a bump, or whatever, the wire can separate, causing problems. Don't be afraid to wiggle these wires and cables. Including tugging on any and all plugs, fusible links, banging on fuses and relays, etc.

Did you pull the fuse block under the hood and check the fusible links? Put a voltmeter on the ends of the fusible link and see whay happens when you bend and flex the link you're checking.

All else fails, take a look at th schematic in the FSM, and start tracing the voltage from the battery to the fuses under the hood, and thence into the cabin fuse block. Just keep following the voltage until it's not there any more

Good fortune! Sorry this isn't more detailed...
Pat☺

 

Outstanding! Thank you for taking the time composing such a thorough response.
I’ll keep you informed of my progress.