So I got a new cluster, I put it in and the back lights won't come on. then later the rpm gauge drops to 0, but the speedo still works. Sounds like a shortm somewhere, but im not sure where to start looking.
There are two plugs under the dash that are easy to get mixed up. One is blue and the other is black. 4 pin I believe. Try checking if those are wrong.
The headlight thing is usually caused by a problem with the switch. You can verify this by slowly turning the switch back and forth and watching what happens with the lights. The switch can be removed and cleaned or replaced with a junkyard one with lower miles. This is worth taking care of because when your dash lights are off, your tail lights are too.
Well, I mean they're controlled by the same switch. If the fault is not with the switch then I'm not sure. However I do suspect they're connected somehow. When I got those two plugs mixed up in the process of replacing my main relay, my tail lights weren't working.