Rev counter intermittent

[jimmymig]

Hi all got a problem with my rev and temp dials on my dash! Both are intermittent not always at the same time and don't work at all if I open ether door any suggestions welcome cheers jim

[ImysE30]

Check the connections on the back of the cluster.

[Brianmoooore]

SI board batteries.
It's not so much that they've failed, but the fact that they tend to short circuit when they do, dragging down the supply voltage to the tacho. and temp. gauge circuits.

[jimmymig]

Thanks for the replies will pull the cluster off and have a look would
This be why dash shuts down when I open the doors?