1998 Buick LeSabre Custom, V6 3.8L

Question-- Where is the starter enable relay?

BACKGROUND
Working on a non-crank situation, I have verified starter motor works, using a jumper cable (momentary contact) between starter and battery
No voltage detected on starter trigger line when key switched to start position.
Intend to replace the starter enable relay, which Buick shop manual and Buick schematic indicate is present in this model.
Relay position is described by Buick expert-- "Under left-hand of instrument panel, above instrument panel fuse block. Look just left of steering column support and on a bracket beside the main wiring conduit. You must remove fuse block cover and panel."
Of course, I already have purchased a replacement starter enable relay, and am searching for anything close in appearance, but nothing, so far.
Most references provide either a text description (as above) or a line-drawing for location. Because line drawings over-simplify, a photo would be even more helpful, but no reference provides a photo of the starter enable relay location.

I'd start at the ignition switch but here'* the wiring diagram.
Component location say'* "Behind left side of dash, left of column.
Shouldn't be hidden. Don't sound like you need it but here'* the diagram.

PNP switch is another.

Thank you! That was very responsive.
Tracing the schematic path from the instrument panel MiniFuse block to the Starter Enable Relay, it seems the yellow and purple lines coming from the instrument panel fuse block go directly to the starter enable relay.
That is where the mystery begins-- the relay must be hiding in plain sight, but I cannot find anything near that matches the starter enable relay purchased as a replacement (having specified the vehicle fully to the store manager).
Because of a tendonitis injury and frequent rains, resolving this problem has been delayed. As of today, however, my mobility is much better, and over the next three days, the weather also may cooperate.
* BTW-- You refer to the PNP switch/sensor as another possible point of failure. How would I test that for voltage? At this point, simply finding voltage at the switch seems to clear the PNP switch/sensor.of involvement.

Ignition switch in the start position supplies power through the 2E fuse and then through the purple wire to the relay but the PNP needs to be closed as well as the starter enable from the theft system. Trace from the ignition switch. Check the 2E fuse first.

I can recheck MiniFuse 2E, but making sure the PNP (Park Neutral?) is closed may need a more detailed explanation.

The VATS instrumennt panel warning (on turning ignition key to start) disappears after about seven seconds, indicating VATS
system is OK with startup.

Of course, I am searching for the starter enable relay.

To test the PNP with the shifter in park back probe the connector between the Yel and Yel/Blk wires and there should be no resistance.

Have you pulled the fuse block down off of the bottom of the dash and looked above where it was?

Yes, I have pulled off the lower dash cover, and looked carefully in the area behind and above the MiniFuse block. In that area, where the relay is supposed to ge located, Ihave not seen anything resembling the starter enable relay. In fact, I have poked and finger-searched the entire under-dash area on the driver'* side. That search will continue tomorrow.

Do you have access to a photo of the relay and immediate surroundings, where you believe the relay is found? It is possible the relay is somewhere else on my vehicle.

I might have a 1997 LeSabre that might be sitting in my driveway right now. I'll try to look in the same area tomorrow.