Learning the ropes...

[Patrick wendynrktex]

I hope I'm following the rules, I just joined and I have several questions I just bought a 97 K 1500 with a 5.7 Vortex . I've got plenty of issues to keep me busy with it for a couple weeks, but right off the bat I need to get the speedometer working properly.. it reads between 68 and 70 miles per hour when I'm actually doing 60
I'm told that this might be due to tire sizing and although I have no idea what the truck came with originally, it now has 285 / 75R/16"'s on it. I'm wondering if I can troubleshoot and calibrate it if necessary without any special tools or diagnostic equipment. If not what will I need and what does it entail?.

 

[RichLo]

Welcome!

One small pet peve of ours is calling a Vortec engine a Vortex (Rifle scope maker)

Thats strange your speedo is reading high, those are oversize tires and it should be reading low (Going 70 and reading 60)

 

[PlayingWithTBI]

Welcome - ditto to what he said^^^

 

[885speed]

Mine reads 10MPH fast in the same fashion. I've confirmed mine to be a cluster issue, which I'd bet money on it being the same case with yours.

The way I confirmed mine was with one of those cheap $20ish OBD2 Bluetooth interfaces you can get off of amazon. Using the "Piston" app to connect to the interface, went for a drive and noted what the speed the PCM says I'm doing vs. gauge readout vs GPS.
Went for a cruise and hit a 45MPH road, gauge read 55, PCM read 45, and GPS read 45.

After Christmas I plan on getting a reman cluster assembly for my truck.