Hi everyone im just getting started on here but i have an account on 1stgen.org. ok heres my senario,Thanks in advance for any help !

When i am driving at highway speed in my 92 dually with 4:10 axle ratios the speedo say im going 45 0r 50 and i know that its reading wrong but the trouble is when the speedometer says it is going 30 (in traffic mostly) it will kick out of overdrive and i have a potintometer from dnr customs and it worked great until my speedometer quit reading correctly i cant stand it kicking out of overdrive when i have to be going on at least 50 or 55 miles per hour.
is it a sensor or a bound a speedo cable?

 

Well i'm not sure on a automatic but I know there is a speed sensor on the transfer case on manuals. Dirt and gum gets clogged around them and can cause them to malfunction. Mine does it ever so often just gotta cleanit. The same sensor might be inthe tcase on automatics but maybe that'll give u a startin point. Hope that helps

 

there is a speed sensor that is electric with a negative pulse it puts out. it sends the link from there either into your computer and then your speedometer, or straight to your speedometer. might try puttin a new vss in there or cleaning your old one

 

thanks y'all that fixed the problem!

 

what exactly fixed the problem? was it a new vss?