Speedometer lying

You need to adjust the tire size in the ECM

 

i don't think he has an ecm.

 

On the positive side its probably saved you getting a few speeding tickets.

 

I have found out x1heavy and Ristow are correct. Had some battery/Alt problems this past week and my speedometer started bouncing around at the same time. Once I replaced Alt, than batteries, the Speedometer went back to just being off by 5mph.

 

So I just look at the back of the speedometer for the switch's and than look up the "switch combo" on-line? This is all new info to me...lol thanks though

 

you need to determine how many revs per mile your tires are. look online for the manufacturer specs. you need the rear diff ratio,and how many teeth on the speedo reluctor,which should be 16 as i recall. basically you need to know the pulses per mile the speedo will get from the reluctor.

tire rev per mile X ratio X reluctor teeth. look up dip switch combo for the number you end up with.

 

WoW! Okay, thank you sir

 

Help with Speedometer adjustment.

the pdf's should have the info you need. looks like you divide the final number by 120.

 

of course,you may have a different brand speedo,and will have to find the correct specific calibration combo.

 

@Snailexpress ....All this effort?

Did you know there's an app for speed? It even has a HUD capability.

Get the app, track your speed. Keep it moving. Case closed.