No longer responds to key fob command to open

Thanks, Joe! I'll order the J36169-A, as you suggest, and give it a try.
What puzzles me is the fob-detect circuit seemed to work for a while, after we put a resistor on the ignition switch line to the PCM. Then, it began to wander in performance, so I suspected the fob button battery until my VOM showed the battery was over 3.X volts.
How did the detect circuit and/or fob fall away from specifications?

Thanks, Joe. I'll try that, since my budget is sensitive.
As for the "dead battery", when I checked the button cell in the fob, it was still within voltage, but I replaced it, anyway, and got the same results.
I'll keep you posted.

Joe, do you mean I could have the same problem, all over again, despite the resistor "repair"?
Where did you learn of this technique? Was it a shop advisory newsletter?

Forgot to ask, what is the fuse electrical value, if it has a value? Fuses are set to sustain current to a certain Ma range, as I recall.

Thanks, Joe, and I rush to assure that am not in trouble.
And, yes, I went through all the GM anti-theft recovery procedures in the documents you provided, although the specific 10-minute procedure seemed only vaguely familiar.
However, I am certain I checked every procedure before turning to the resistor technique. That surely included the 10-minute wait, with ignition "on", while the Security warning flashes, as well as two or three variations on that procedure.

Not yet, Joe. I am distracted with a water heater problem. Will let you know, appreciate your interest.

Joe, here is an (1) update, with an (2) additional question placed in this thread because I did not know how to reach you, otherwise. You know at least as much about my car as I, so the question is submitted that way.

(1) The GM bypass link project (above thread) was postponed by the water heater, which you may recall my mentioning. That link should be simple to construct.

(2) The car suddenly refused to start, after parking in a residential driveway. Fortunately, it is parked in a friendly location, so I spent much of last night-- in the driveway-- trying to determine the cause. All the instrument lights come on with the ignition switch, and I heard no problems as I turned the ignition key. Essentially, the starter turns the crankshaft, but with no ignition.

The first time this happened, the engine started briefly, but stuttered strangely, then stopped. Further efforts with the starter brought no response from the engine, although the car lights, exterior and interior, still work normally. To prevent sulphation after all the starter motor drain, I applied my Schumacher battery charger on a slow recharge cycle. The battery (three years old) is now back at 12.8v and "100 percent".

Fortunately, I noticed the motor switch for the windows produced no response, not even a buzz. This persuades me that the engine startup failure happened when a large amperage relay fused and shut the starter circuit down. Why GM put the window motor on the starter circuit, I have no idea. But everything else on the car seems normal

Since I don't have the wiring schematics, could you tell me what fuse I should examine first?

Joe, thanks for your quick response.

1. The starter engages every time, but the motor does not start, and makes no sounds as the starter runs. The two exceptions to that behavior were (1) when I first encountered the problem-- the motor responded, ran/stuttered for a few seconds, and thereafter was unresponsive and (2) after an estimated 12 hours, the motor made noises and vibrated on a second try at motor start, but thereafter was unresponsive.
2. As noted in the previous message, on the theory it was a depleted/below minimum battery, I have recharged the battery with a Schumacher automatic battery charger. At beginning recharge, the battery showed 97 percent discharged, but was restored to 100 percent after only a few minutes, with voltage of 12.8.
3. All lights are operating.
4. Window motors unresponsive-- not even a buzz.
5. Key fob at close range opens and locks doors and trunk button opens trunk (I did not try the emergency horn button).

The schematic shows fuse 2E in the fuse block runs to the starter enable relay on schematic left side and to the ignition switch at schematic center (I mention schematic position only to show I follow).
There are two fuses along the way--
1. Fuse block fuse 2E is 10A, but since the starter engages, that fuse and the starter relay are okay.
2. Fuse block main yellow wire branches at S217 and the right branch enters the ignition switch, and a red wire emerges, running to the MaxiFuse block, to fuse A2 60A.

Okay, so far? If so, that means I have no issue on the starter side, but the ignition switch and its MaxiFuse could be suspect.
The ignition key travels smoothly and never has an "issue" with engaging the starter motor at "Start" position.

1. Test for spark, by removing plug to observe its firing gap. I do not have a remote starter cable, so a friend must help (no problem).
2. Spray starting fluid into what opening? I remember the old, carbureted engines-- after removing the air breather cover, squirting into the open throttle throat. Is this similar?
Thanks, Joe-- I'll keep you posted.

Joe, could you re-attach the power window schematic? It never arrived. When you said it was attached, but since I had gotten no other, I thought you meant the schematic you already had sent to me.
At this point, it puzzles me the power windows switch ceased operation when the motor would not start, yet the schematic shows them unrelated.

June 14,. 2022

Joe, here is the latest:

Having checked the battery, the starter relay and the starter, itself, for function, all appears okay-- they consistently respond each time I turn the ignition key to start. So, the problem has been isolated to ignition and/or fuel.

1. Fuel-- This car was allowed to reach a low fuel tank level frequently, so debris could be in the line and filter. For filter replacement, I have applied Liquid Wrench to the flare nut which screws into the large, silver nut on the end of the filter. This operation carries the danger of rounding the nut, so the wrench must be a flare nut wrench of exactly the right size for the best grip on the flare nut. An adjustable wrench or a "close enough" SAE or metric wrench permits too much play, although they can be used to apply counter-pressure on the silver filter end-body nut, itself, to prevent twisting the fuel line when I apply pressure with the flare nut wrench. The filter is possibly original and is firmly screwed into place.
2. Starter fluid test-- After viewing the throttle body video for location of the throttle throat, it was not helpful-- there was no clear depiction of its location. I am familiar with the older Holley carburetors which had a throat covered with the air cleaner but saw no comparable opening with the 2CarPros video-- please indicate where (0:00) on the video I can find the view you wanted.
3. Ignition spark-- removal of the easiest plug(s) has been difficult because they are very firmly screwed into place, and the working area is very confined.
* I found a video discussion of the ignition coil for the Buick engine and wonder whether this might be a more practical test for spark. Granted, it is not a test of spark at the end of the spark plug, but it might indicate something useful. At 3:57, the video shows the ignition coil and module assembly, and removal of the upper module assembly, permitting visual check on spark between the two voltage poles. Let me know what you think.
South Main St Auto Repair (NY-based). Location of ignition coil and ignition module.
https://www.youtube.com/watch?v=G1E3h9KFO1M
* For a second time, I am checking the fuses, MaxiFuse and MiniFuse, just to make sure I did not miss anything. I found the 30A MaxiFuse which controls the power windows, for what that is worth. The fuse is covered by an aluminum (?) cap which has no contact points, and it strongly resists being pulled out. Can that fuse be removed, manually? And if so, can I check continuity across (what I presume to be) its two leads? Of course, the inoperative power window issue may not be directly relevant to starting the engine.