'90 Ranger XLT - Tach issues
 

Hi all,

I have a 1990 Ranger that just recently did something really weird. When the truck is off the tach is at its normal 0, but when I start it the tach jumps up to about 3500 and sits there at idle. Now the truck idle is still normal, around 10k, but the tack now seems like it thinks the 3500 is where it should be at idle. Any ideas on what could have happened?

Thanks,