I left my Haynes at my parents' this last weekend and can't get it until December. I paced someone in my truck and discovered (like I thought) that my speedometer is about 5 - 10mph off). I want to be sure it isn't the VSS that's bad before I take it to a speedometer repair place and have them inspect the gears. Can anyone give me some tips to test the VSS or explain how I know if its bad? No trouble codes are being thrown right now, so that option is ruled out.

 

None of you has anything to offer? Here's something else -- I have 16" wheels on my truck but I need to double check the tire size. Where can I determine what the stock wheel size is for my truck to ensure I don't have tires that are throwing the speedometer off?

 

Look inside the driver side door for the tire size should be there .

 

IIRC ... the `97s still used the gear in the tailshaft trick to run the speedo, didn't they? I know that `98s dispensed with that and use the rear wheel speed sensor.

Wheel size won't affect speedo calibration. TIRE size will. I believe that the speedometer is calibrated for 245's which is the stock tire (although some came from the factory with 265's ... mine did).

 

Just for clarity - rim + tire = wheel

But I know where you're going with that. I haven't had time to check what size tire I'm running right now. I will in a couple of days.

 

I have 16" wheels
Just for clarity - rim + tire = wheel

clearly sounds like a tiny *** wheel

 

Well ... that for damn sure explains the speedometer calibration problem ...

 

Just got around to remembering to check what size tires my truck is rated. 225/75R16, which is what is mounted all around. That's why I would like to know how to tell if it's a gearing problem with the speedometer or a VSS problem.