suspension leveler mystery

So, a woman’s car died out front of my apartment today and in the course of the standard pointless bullshitting about what it might be with some other guy in my complex, we observed something odd. She had an early 90s (or so) Buick with a supercharged V6. Here are the symptoms:

• Car would not turn over – in fact, the ignition made no noise on turning the key at all
• The car died suddenly while driving
• There was still 12V and going strong at the battery terminals
• There was a small device to the right of the engine that, when the ignition was on, was sputtering and vibrating madly and erratically, sometimes dying entirely and then shaking violently. (?!)

On arrival, this woman’s dad mentioned he thought it might be a “leveler”, but when I pressed him for details about what that was (being the curious sort that I am), he admitted that he had no idea.

Well, I talked to some people (hi Matt!) and he mentioned that Buicks do indeed have some sort of auto-leveling system. I have been googling, but I can’t find anything conclusive. It appears to be something that Cadillacs also have, and so I am guessing it’s probably some GM thing they have on all their sedans. This page gives some hint in describing the Lincoln’s air ride suspension:

Air suspension is provided in the rear by the use of two air springs. One leveler is used between the air springs and controlled by the module and compressor. The Mark VIII rear air suspension is fully independent and mounted on a rubber-isolated rear sub-frame. A rear air suspension compensator link controls toe-out during braking. The rear air spring is mounted between the lower rear air suspension arm and bushing and the body. A rear stabilizer bar is standard on the Mark VIII.

I also found someone asking about a problem with a Caddy that sounds very similar:

I had my rear air suspension looked at and was told that there was no detection of any kinds of leaks in the leveler itself. So I am curious, it sounds like the motor that levels to car is on its last leg, since it is very loud and tends to really shake when I see it engaged under the hood.

Anyone have any ideas what this might have been on a Buick? Am I on the right track? The other symptoms I guess pointed at some sort of ignition problem (not the starter, because it wouldn’t have stalled – and not the alternator because it would still turn over). In any event, it meant she wasn’t gonna be driving it home, no matter how long we stared at it (more on this later). But the weird freaky vibrating thing I couldn’t identify was a new one on me.