welll my car did not come with a tach so i was just going by what was told to me and was just trying to relay the info, plus there is other stuff you got to do to make the tach work like which wire in the back of it to cut think it got to do with the pulse or something of the engine not sure but if you cut the wrong one it will not work right. you have to go according to your motor wether it be four, six, or eight cylinders. also got my tach light to come on only when i turn my lights on rather than it be on all the time.