I recently did an absurd amount in one go: clutch, new turbo, new cat, new starter, new alternator, new battery. Everything seems fine except the electrical system, which is now acting kind of weird.
Prelude: On finishing all the work the car would crank slowly but not start. Being a moron, I immediately assumed it was the starter. Tried to jump the car briefly, thinking they might have sold me an uncharged battery, but it would still not start. Bought a new starter, installed, still no start. Reexamined my assumptions, and let the battery charge from another car for half an hour or so, and it fired right up. So. Thanks Sears! Charge your batteries next time.
Car runs fine for a week or so until today when all sorts of electrical wackiness begins. The instrument cluster backlights began to flicker at a steady rhythm, seemingly independent of RPM. The instrument cluster LCD then flickered and died entirely. When I turned the car off, the voltmeter read ten volts. Ruh oh. Tried to start, and it fired right up, which it should not do at ten volts. Took out the multimeter, I get 12.5 volts across the battery terminals, 14 or so when the car is running, so both alternator and battery seem fine.
Instrument cluster LCD then started working with the ignition on but the engine off. As soon as I start the engine, the LCD goes dead. Voltmeter reads 14 when the engine is running, 8-10 when the engine is off. The fuel gauge starting jumping around erratically. Then one of the headlights went out, only about six months old.
I'm at a loss here. Is it just my instrument cluster going out? What about the headlight then?
All terminals are clean and tight, no alternator/battery service light, everything seems good.