94 e36 tach help

Does anyone know why only the tach would not function? Does this unit use nicads like older clusters? Where is the sending unit. The mileage reset test causes the tach to fully sweep, but otherwise it satys between 500 - 1000 rpm. Local garage said I needed to take the car to the dealer.

Michael

Geez, no one on teh internet will help me. I've posted this message everywhere and except on wise guy who said he didn't use a tach I had no help. Please any thoughts would be great!

Michael