Anybody out there know the likely reason for a very erratic rev counter before I start stripping out the dash. Nissan Primera. Occasionally works but more normally bounces from one and of the scale to the other, any ideas welcome.

i have seen cars with charing problems do this, but not on a nissan. has there been any issues with the battery lately?

Thanks Patrick, just bought the car, so little history known, previous owner says had no problems other than rev counter problem in last 2 years. Would disconnecting alternator prove charging problem? Cheers