speed sensor not accurate

[d94]

when i first got it, it was spot on..but not much after i noticed it was off by as much as 5mph..and obviously it skrews up the nav..is there any way t tune it? or is it possible the installer didnt set it up right?

[whtcrxghst]

Did he even hook up the VSS wire?

[d94]

Did he even hook up the VSS wire?

claims he did..i mean i do get speed pulses...buts its consistantly off by 5mph

[whtcrxghst]

When you go into hardware info, connection status while moving, does the speed pulse beep?

[HiFiSi]

There's a good chance that it's not the unit that's off, but your car's speedometer. A good amount of car's speedos aren't very accurate. In fact, some manufacturers (like Volkswagen, IIRC) purposely set the speedos to misrepresent the actual speed of the car.

 

Or... did you recently get new tires or wheels? If you get a different diameter that will throw it off.

[d94]

There's a good chance that it's not the unit that's off, but your car's speedometer. A good amount of car's speedos aren't very accurate. In fact, some manufacturers (like Volkswagen, IIRC) purposely set the speedos to misrepresent the actual speed of the car.

 

Or... did you recently get new tires or wheels? If you get a different diameter that will throw it off.

yeah..i i can see this being possible..but still

I did get new tired, but now new wheels

 

and the speed sensor does beep

[HiFiSi]

It's possible that the diameter difference between new tires with full tread and worn out tires (of the same size) with little to no tread could account for that.

[SpecialFX]

There's a good chance that it's not the unit that's off, but your car's speedometer. A good amount of car's speedos aren't very accurate. In fact, some manufacturers (like Volkswagen, IIRC) purposely set the speedos to misrepresent the actual speed of the car.

 

Or... did you recently get new tires or wheels? If you get a different diameter that will throw it off.

 

I can confirm that for VWs. I knew it from the forums already, but now that I use the D3, I can confirm that it reads around 5mph higher at highway speeds than the speedo in the dash

[BuffaloSS]

I don't get a beep or even a pulse count with my setup and it's still pretty damn accurate. I set it up through the GMOS-LAN-01, which is supposed to handle the connection for the VSS for you.

 

Can you verify how far off it is by selecting the "gauge" screen, setting the cruise at a steady speed, and watching the digital readout for MPH?

[HiFiSi]

That should work fine. Just set your speedo to whatever speed and see what the D3's speed gauge reads. But if you're not getting a VSS signal, I don't know if the speedometer on the gauge view will work using the GPS signal and gyros for an estimated speed reading or if it will just sit there at 0mph. Give it a shot and see.

[BuffaloSS]

Well, I attempted to recal the system and got the message stating that the VSS was not connected so it would rely on GPS speed data. This is pissing me off. I made sure the VSS connection was good, and then cut and reconnected it anyway. Still nothing. Contacted metra who makes the GMOS unit and they said to reset the module by yanking the neg cable for 10min, and then cycle the ignition 2x. Still nothing. I'm going to see what crutchfield says, but I may need to just tap into the VSS signal directly instead of via the GMOS unit.

[scotspitch56]

i never set mine up and its right on the money. no clue how that's working

[BuffaloSS]

With impalacustom's wiring guidance, I was able to hook up directly to the VSS signal in the engine bay. All is well, now. The GMOS does not do this for you in the 2006 Impala.

[jlong1987]

VSS wire with out any other factors effecting it is only reachable right behind the instrument cluster. VW VSS Wire = Pain in the A**