Found the culprit .... the previous owner (my Aunt) installed a 'Negative battery cable theft protection quick disconnect' to the neg battery cable. It had corroded so bad and lost connectivity, I lost ground.
Didn't make sense that I got good readouts from battery post (where I tested my continuity to various wires) but never on the frame or engine block. But soon as I used the 'quick disconnect apparatus' on the neg cable as my ground, lost all continuity!
As someone said in a similar post '90% of the time, it's the ground...'
Well, got a new solenoid out of it ...
I am (also) glad you found the issue. I was preparing mentally to provide a bunch of info re: what to check and how, going after "the usual suspects," which would have (of course) turned into a little dissertation of sorts.
We all have our favorite approaches. Mine includes at or near the top of the list, making certain the battery is fully charged, then checking for the battery's susteaned voltage when load testing with a load of 1/2 of the battery's Cold Cranking Amperage (CCA of 500Amps = a 250Amp carbon pile load) where the battery voltage needs to remain at 9.6 volts or higher after 15 seconds. If that fails I then replace the battery before . This takes a bit of a special piece of equipment, esy found on Amazon. Search on "battery load tester carbon pile" and look for something like what is in the following link. I prefer to get the higher capacity testers as they will often work with 12 or 24 volts (large trucks, buses), and with batteries that are very high CCA a in parallel. Invest once, do not buy twice...
There are less costly 500 amp carbon pile testers that will work well as long as you do not plan on ever working with it on larger equipment with 24 volts or higher than automotive level of amperage draws. And, there is a very inexpensive assortment of non-carbon pile battery testers that work on a different electrical set of principles that reportedly work plenty well. But, being old school I like to see things smoke <heh heh>. That said I also have a lighter tester with no carbon pile for testing batteries, and it seems to have a good set of ratings. Search on "automotive battery testers" - this is the one I acquired,
MOTOPOWER MP0515A 12V Car Battery Tester Automotive 100-2000 CCA Battery Load Tester Auto Cranking and Charging System Test Scan Tool Digital Battery Alternator Analyzer
I have not yet tested the MotoPower MP0515A unit on anything other than a small Power Backup battery, but with over 1300 ratings and 4.5 stars it is solidly crowd favorite. Then I look at and check the battery terminals, and test both teminals and terminal lug connections for voltage drop. Next, the negative battery post to both the chassis and engine voltage drop. Using a high capacity inductive ammeter (measures up to 500 amps) I check engine cranking amps after disconnecting the ignition coil so the engine does not try to start on cranking. I follow an old school rule of thump, one amp per cubic inch of the engine. So, my 351 in the 1973 Mach 1 ought not exceed 350 amps (spiked, the continual cranking will settle down to a level less than the initial amps). If you amperage demand is higher than that the engine may be resisting turning over due to an internal problem, the starter may have an internal problem, or the ignition timing may be way too far advanced. If the amperage is far too low the brushes in the starter may be too worn to carry the current needed to crank the starter over, or there is high resistance in the starting current path (time to do a more extensive voltage drop set of tests, no more than 0.1 volt drop per connection.
Somebody stop me! I tried to not turn this into another lengthy response. I hope my fellow enthusiasts are able and willing to forgive my natural exuberance when it comes to all things automotive. Okay I will stop here, although the are other things to consider and test for hard cranking or slow cranking. The preceding covers most issues I have come across.
