I have an '83 300SD.

My tachometer is very intermittant (mostly not working). I have checked and changed the fuses. Don't know quite what else to do. I would like to have the tach working so that I can troubleshoot an intermittant idle problem.

What would be the best way to troubleshoot my tachometer?

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Big Fred

(RIP Sept '10) 83 300SD Turbo Diesel (aka "Rocky")
(RIP April '10 - Accident) 86 Chevy M1009 CUCV (Blazer) - 6.2L Diesel (aka "Ogre")