Saab C900 - Sudden no crank condition

Was on vacation for a week. Came home, went to start Saab project car. Click. Probably a parasitic drain on the battery while inactive (when I got the car there were several fuses missing, which I replaced - a suggestion that these components may have caused issues in the past). Stuck jump box on the car. Click. Check voltage at battery and starter: 12.48v. No joy.

It's gotten pretty hot here, and as this coincides with the starting problem, I'm leaning toward the starter solenoid as the culprit (unlike so many systems on this car, the starter is conventional). I guess this means yanking the starter, which shouldn't be too difficult, and cleaning and bench-testing. Any other brilliant ideas before I grab the tools and start working?

I would rule out the ignition switch. You can bypass it with a jumper wire stuck into a couple sockets in the round diagnostics plug (~1/2-inch diameter) with five or so sockets that's located on the fuse box. (That plug was for techs to attach a simple switch box to so they could test certain things while under the hood.) I'll look in my notes tonight to see if I've recorded which ones to jump -- it's been a while since I've done this.

Failing that, you can also bypass the ignition switch, with a bit more effort; I'm pasting here some instructions I wrote elsewhere at some point -- they're for bypassing the whole switch to run the car, but contain info about how to send electrons to the starter without the switch. (Cliffs Notes: get 12V from the gray wire and send it to the yellow/red wire, which goes to the starter. REMEMBER TO PULL THE CAR OUT OF REVERSE FIRST.) I see that I put connector code letters in there, so I assume you can get details in the Bentley manual, if necessary:

To bypass the ignition switch and start/run the car,  you make a small wiring "octopus" but with five wires, so, it's a "pentapus":

• Remove the center console to access the ignition switch, then pull one wire so you can see what size spade connectors you'll need in the following instructions.
• Take five 6-inch wires, all gathered and connected to a single male spade connector. This single connector is the pentapus's head.
• Crimp male spade connectors to four of the five wires.
• Remove the six wires from the ignition switch. Note their positions prior to doing so -- take a picture!
• Insert the spade connector to which all five wires are crimped (the pentapus's head) into the connector for 30 (gray and gray/red).
• Connect the wire labeled S (green) on the bundle to the car's corresponding wire.
• Connect the wire labeled X (red, two wires) on the bundle to the car's corresponding wire.
• Connect the wires labeled 15 (green/white) and 54 (gray/white) to their respective wires on the car's wiring.
• When all of the wires are connected except for yellow/red, the car is in "run" mode.
• Touching the fifth wire to the yellow/red wire will run the starter, like turning the key. Remove it once the car fires up. Don't put a spade connector on it.

Thanks for the detailed info. I pulled the starter and bench-tested it - it seems to operate correctly, with the solenoid nice and snappy in both directions and the gear spinning as it should. This suggests the ignition switch may be at fault. I'll slap the starter back in, then start troubleshooting. Stay tuned.

Voltage from the ignition switch checked out fine. Starter back in, everything hooked up, and the jump box on it, and it fired right up. Must be a tiny flat spot in the starter. Or some sort of Nordic poltergeist rebelling against the 85F+ temps we've been having lately.

Spoke too soon. Same condition this morning. As all the voltage checks out, it's either the starter or the solenoid. I'm just replacing the whole assembly. Ordered a cheapo replacement from Amazon. I wish my local rebuilder hadn't closed some years ago....