ok

last night i fixed my radio and interior lights blown fuses and on missing fuse.
well now the tack dosent work. any idea? i need this truck to work good it is for my bussiness and will be used every day. ok back to cutting the hell out of my mustang. ( floor pan replacement)

 

I am going to be brave and state the obvious. We all forget this sometimes. Check the fuses you put in, and check the ones in that give the power to the tach. A visual test is easy, but to really test, use a multi-tester. Make sure current is flowing through the fuses.

Now when you fixed the radio and interior lights did you only change the fuses correct, no messing with wires changing bulbs etc? Then we need to know what "missing" fuse did you put in?? If it wasn't there before then pull it out (truck off) and start er up and see if tachometer works, if not, then its something else, and you should be able to put it back in (truck off please). If the tach does work after the fuse is out, and that fuse is indeed needed, then someone took it out for a reason meaning there is a short or something electrically wrong in the circuit, either because it was blowing fuses or the tach didn't work. Check and see if this "missing" fuse does anything with the tach or related circuits or if it is needed on your current year and options. If the latter scenario is true and you need that fuse you will then have an electrical hunt on your hands.

Thanks, good luck on the mustang.