I have a 99 Oldsmobile 88, 3.8. It will turn over, but won't start. Power windows, seat, won't work when it does this.

Have you checked the ignition switch to rule that out as a cause?

What other checks have you performed to try and track down the issue?

I've checked grounds, replaced the fuel pump, and bus ground connector on the driver'* side. It runs sometimes, then other times it won't. It will turn over, but won't start. When it won't start, the fuel pump, power seat on the drivers side, and the power windows won't work.

Not sure what else to check. Think if it was the ignition switch, it wouldn't turn over at all.

Have you lifted up the carpet, to feel for moisture.....I'm not sure where G202(common to power seat and power windows) is, but that is the place I would be checking first....maybe someone can pinpoint this....

I Googled the ground, G202 and came up with this

https://www.justanswer.com/oldsmobil...-run-dies.html

I saved the information from this link. Going to try suggestions from that link. Further down the feed, it explains how to reground those wires.

That ground, G202, goes to a splice, that has quite a few circuits on it......that'* why I wondered if there was a leak somewhere, and the floor under the carpet was wet, causing corrosion problems....