Ok so was tired of my inaccurate tachometer and MPG gauge and constant inspection light.
So I soldered on new batteries on the SI board, went well. Inspection light is good, but the tach still wobbles about and isn't accurate and gets more inaccurate the high the revs are. I.E, idle is accurate but on rev limit shows reads around 4k. The MPG gauge is still swinging about like a demented pendulum.
I know the MPG gauge is calculated from the tach and speedo, so I'm guessing if I figure out why the tach is crazy the MPG gauge will sort it's self.
It is a 325i cluster with an m30b35 engine.

