Speedometer and voltage problem, please help

Yesterday after I filled up with gas, I noticed that the speedometer wasnt working right. It would randomly drop back to "0" This was happening at highway speeds. If i hit the gas it would sweep back to where it was supposed to be, but when i took my foot off the gass it would sweep back dopwn towards "0"
Thismorning, I started the car and the voltage gauge went up passed the 3/4 mark (i guess thats 15.5 volts) it went up almost to the red, it had to be around 16.5-17 volts. I drove it for a little while and the speedo still had the same problem. after about 10 miles of driving the speedo went back to normal and the voltage was slowly coming down it was at about 15-15.5 at that point. by the time I got to work (25 mile drive) speedo was acting normal but voltage still seems a bit high in the area of 15 volts.

:confused:

So, are the 2 things related?

and

What would you recommend I do to solve these issues?


Thanks guys

Have your alternator output checked out by a shop; most auto stores will check them for free. The alternator has a built in regulator that controls your voltage.

do u think they are related?

I just did a quick 10 mile drive and the speedo acted up 2 times. the Voltage seems to be slowly lowering back towards the normal. Its halfway between the 1/2 and 3/4 mark.

thanks