The short version: The Security light on the dash is on all the time. The car didn't appear to have come with carpeting on the trunk lid. I disconnected 2 electrical connectors there at the trunk latch, and turned the key on. Still had the Security light on. I checked around the hood latch area, found no place where a vertical switch plunger might have once been.

I found an earlier thread that warned me away from disconnecting anything with a yellow connector or yellow harness (SRS system), and I did see some of the mentioned connectors (stayed away from 'em) but nothing that looked like it might be responsible for the Security light staying on. That's what clued me in to looking for problems at the trunk or hood latches, BTW. Oh yeah, the car starts up and runs fine. A previous owner had covered the lights with cardboard, but I'm going through and trying to fix everything properly. The car is driven by my daughter (in college).

Any advice on tracking down the reason for this light staying on? I don't have a manual for this car, at this time.

Thanks in advance,
Dan_in_WA

If you can start the engine every time, with the Security indicator on the dash "ON" solid (not flashing), it means that your BCM (Body Control Module) put the former anti-theft system into Failsafe Mode.
The usual reason for this is that one or both of the 2 tiny white wires that come out of the Ignition Lock Cylinder BROKE OFF..."while" the car was being driven, and had already been started normally by it's special PassKeyII ignition key (with resistor pellet IN the shank of the key, and a contact on either side of the key).
If you want to get this fixed "correctly", you will need a NEW ignition lock cylinder assembly (the old one cannot be repaired in 90% of cases because the tiny wires break too close to the cylinder...and since one HAS-TO take the steering column apart to replace/fix this, you may as well put in a NEW part). GM had a T.S.B. (Technical Service Bulletin; meant only for GM repair technicians) about these lock cylinders, and 'may' have released a revised Part #. They can also be purchased at Auto Parts stores.
The difficult part of the job is installing the new lock cylinder and it's sheathed wires. The steering column has to come apart, and special tools are normally used [CAUTION: disable your SIR/Air Bag System "correctly" BEFORE working on ANY part of the steering column!]. A very "experienced" mechanic 'could' do this job at home...but it usually has to go to a good repair shop, if not your local GM Dealership to get done.
*Recommend you do NOT do the so-called 'bypass' of the Anti-Theft System that some folks have posted on the www; your Insurance Company will NOT pay any claims if that is done.

I think that bypassing the resistor embedded in the key, by connecting the same value resistor to the two white wires (after cutting them) that are normally connected to the key cylinder in the steering column, will fail an insurance claim ONLY if the claim was for a stolen vehicle. I don't think a bypassed key resistor would matter if the claim was for a car accident or any claim other than a stolen car.