I've seen some auctions on ebay about a spaztic tachometer, but this one really has me wondering. First, the tach will NOT work up until you get about up to 3000rpm(it just jumps right to it), an when it gets to 3000, it quivers up and down a bit. heres the catch! It works absolutely FINE when the A/C is on?!?!?!?! Someone at least provide an explanation of this!
BTW this is a 1982 300D Turbo Diesel with 195k on it