93 Buick LeSabre randomly dies - all electrical is gone

Sounds like either a self-resetting breaker is blowing then resetting, or a cable (perhaps a ground?) Has broken in such a way that when it gets hot, the break opens up, and when it cools back down, the break closes again.

I think I have a manual that will cover the schematics of this year, and will see if I can find anything unusual about it.

The earlier passkey systems usually worked only when you were trying to start the car, not after it was already running. (I just defeated my system on the 90 Reatta because it was so touchy.) I'll see what changes were made to the later systems.

I have had a bad ignition switch on a Ford behave similarly, not the key or the cylinder, but the switch itself.

Will get back with you.

I did a quick schematic check, Libby. The radio memory runs from a line that should be hot at all times. It does not go through a switch or relay, etc. (So forget the ignition switch idea).

To totally lose power, intermittently, I would look at

(1) battery cable....again... The Buick battery cables are often multiple side mount units. They can become corroded inside the rubber covering, and this is a common mode of failure. The rubber can be pulled back and the internals can be cleaned but this may provide only temporary relief. For example, the cable to the starter may work okay, while the other may not be getting current due to corrosion.

(2) I suppose the battery itself could have an intermittent cracked plate. Not too usual, but it has happened.

There are other places where intermittent contacts can result in this sort of behavior. Maybe the other regulars know some of the weaknesses.

Even the headlights go off, and I reconfirmed that the radio loses it's memory. We cannot find a ground cable at all from engine to chassis. Does your schematic show where to find it on this car?

I'll look. On one of my cars the battery negative has multiple cables, one to the chassis, one to the engine block, etc. There may be other ground straps from block to chassis as well.

Any time you have those multiple cables, there is the possibility that a failure will occur. The cables can look great, but have internal problems.

You are describing a main battery cable failure. I would be cleaning 'both' ends of the battery cables. The other ends corrode and most folks forget about them when cleaning up cables. The negative to the engine block one in particular.

GM's 'usually' have a wire mesh cable from a transmission bell housing bolt to the body. They also have a small negative lead from the battery to the fender. When the mesh cable goes bad, it will run for a while off the small feed, but the insulation will soon melt and the wire will burn up. This usually manifests itself as a dead battery though, not a dead car.

Mike

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