Intermittent tach on 93 A90 V-6

[SELECTTRA@aol.com]

Once every several days tachometer inop from startup to destination. Restart
tach inop to destination. Restart 50/50 chance of tach operation to
destination. Restart the tach seems ok for a few days!  Awfully tough to
trace an intermittent like this....if noone has experienced this, we will
hookup an external tach tapped into cluster impulse wire and if it is inop at
same time as OE tach, then we know problem is input source.  If external tach
works and OE inop then we know problem is in cluster.

So, I have a troubleshooting method, but if someone has experienced an
intermittent tach on this model, please post/E-mail a reply.