Hey, newbie here. I've got a '99 Jeep Cherokee, just bought it a few months ago. It was running great until last week. Now it won't start, and when I try to start it, it makes a high-pitched screeching sound, almost a sort of shrieking, which continues as long as the key is in the start position, and for maybe a half second longer after I turn the key back. All the lights, radio, and automatic locks work fine.

(No idea if this could be relevant, but the first time this happened, a little over a week ago, it had been raining heavily for several days. A friend suggested I wait and try again when the weather dried out. Unfortunately, that hasn't happened yet. It's continued raining off and on ever since. I've tried to start the Jeep a few times, but it always makes the same high-pitched screech and doesn't start.)

It could be the the starter solenoid. try tapping the starter with a hammer and then try starting it. the shrieking sound may be the stater gear spinning inside the housing and not engaging the flywheel. If tapping the starter works then you should change it. The mechanism inside the solenoid and starter is probably frozen from corrosion.

Thanks for the quick reply. Tried it, but so far no dice. It does seem like the screeching doesn't start quite as immediately when I turn the key after tapping the starter. But it still screeches and doesn't start.

Is it a metallic screech, or more of a rubbery squeal? Pop the hood and have someone else crank it while you try to find the source of the noise.

First place my mind goes is to a bad starter, which will sound like a metallic screech of steel on steel. Starters are not expensive and are relatively easy to replace. If you can change your own oil, you can swap out a starter.

Good to know. I'll try to get someone over here to crank it so I can have a look. The sound seems more rubbery than metallic, though, now that you mention it.

For some reason I'm hearing the screeching in my head of a starter that isn't shimmed properly. Like an ol chevy tree fiddy. Those starters can screaaaaaam

When you hit the starter, its a whack, not a tap tap. Just not too hard to break the casting

i'm thinking you probably have two issues going on here.
a bad starter not starting the jeep, and maybe a seized pulley, whether it's an idler pulley, alternator pulley, a/c compressor....
as mentioned, have someone try to start it while you look closely to see if the belt is turning or whether a pulley isn't.

and yeah, those 350 starters can scream when not shimmed properly. haha