I just got a new battery installed today, and now the speedometer does not work that well. I didn't put the battery in, since it was still under the prorated warranty amount. I don't know if the technician would've messed with the speedometer or not. Regardless, I will speed up to at least 10 mph and then the tach starts to move. It used to move right when I hit the gas pedal. Even when I am going faster, its lagging behind where it seemingly should be. I'd bet money that its not working properly. How should I test it or try to start and fix it?

 

Tach doesn't work right, or speedo? Or both-?

 

the speedometer works slowly, as if its drunk. I would be going like 50 mph and letting my foot off of the gas and the pointer is at 45 slowly moving up to 50 and then sticks for a second and then goes down. I thought that the "tach" is the term used for the little pointer showing me how fast i am going.

 

I have no idea on that one. Haven't seen anybody post that issue before. Sounds like the speedo cluster itself is whacked. You could try disconnecting the batt. for a while to reset everything.

Tach is short for tachometer (engine speed or rpm = revolutions per min. of the crankshaft.)