I noticed last time I had my GPS in the Disco (still need a good name for it) that my speedometer is off. The faster I go the further off it reads. When my speedometer reads 75, my GPS was reading 68. At 25, GPS read 21. Could this be the vehicle speed sensor going bad? Is there any way to test the VSS or is it simply a replace and see part? It's not a major concern, I figure I'm going fast enough when the truck stops accelerating at top speed. LOL.

 

Welcome to the wonderful world or Land Rovers.
Everybodys speedo is off, mine by exactly 5 MPH.

 

Got to love the british and mine is 6 off

 

Why automatically blame the odometer and speedometer ???? what about the possibility theat the gps is wrong ??? As far as I know, since it is satelite related,the gps cannot compensate for the distance travelled when going up or down an incline etc...

But then again I don't own one.

 

Gps use at least 3 satellites to work and can read elevation changes I have used them for
years backpacking in mountains.

In my Disco the speedometer is about 1 mph off with larger tires my odometer is
5.5% off ,,to get the right mpg I add the 5.5%.
I have 3 Gps units and have used all of them in the Disco each time I got a new one.
The data has remained the same.

I think it could be the VVS going out. The miles per Hr should stay the same at all
speeds if you are off 5 mph at 25mph then it should be off 5mph at 70mph.

 

According to my TomTom, the truck speddo is off by 5, my wifes Volvo is off by 3, the Camry that we used to have was dead on.
I do not think that anything is 100% accurate.
I really do think that speedo's loose calibration, my odometer is dead on, one mile IS one mile, but if I drive 10mph I am going 5, if I drive 90 mph I am going 85. So I just compensate in the truck, the hard part is now that it is habit, I'mdriving too slow in another car.