This makes no sense . . . . .

[bramfrank]

I had to go to a client's out in the country today. I didn't have the location in the RB5 vehicle navigator and they don't have a street address, so I took out my Garmin 3490 and popped it on the windshield to route me to the door.

Interesting; The speed as indicated on the RB5 matches the vehicle's digital readout which I know from experience reads about 4% optimistic with my winter tires installed.

The Garmin read 4% lower than the vehicle nav which tells me that they do not use the GPS network to calculate the vehicle speed, but just get it from the vehicle . . . . . . and that's just dumb, since they have accurate vehicle speed as calculated once per second from the constellation of satellites - why not use the GPS to set the vehicle, like they do for the clock?

Edited March 15, 2016 by bramfrank

[silenze]

You dont have to set your clock?

That is amazing

I have to set mine evey week because it gains a few minutes . Sometimes a few hours.

[bramfrank]

My '11 also needed to have it's clock reset regularly. With the factory nav the radio there's an option that allows the nav to drive the vehicle's clock, so it is always accurate.

You'd have thought that even if they didn't use the GPS data to trim the speedometer accuracy, that they'd display accurate speed data derived from the constellation on the nav screen, rather than simply parroting what's on the dash. I wonder if the trip meter stats in the nav are derived from the GPS speed or from the vehicle's idea of how fast it was going?

Edited March 15, 2016 by bramfrank

[jkeaton]

You dont have to set your clock?

That is amazing

I have to set mine evey week because it gains a few minutes . Sometimes a few hours.

Mine did to until the dealer replaced some module, now it keeps time like it should.

[dhh3]

Same thing in my Nitro ^^. Clock does not get its setting from the radio, but some other module in the car. There was a TSB on the 2011 Nitro for this. The clock in my DJ is accurate. The Navus 2 (Garmin) that I had in my Nitro got the vehicles speed from the satellites. I always set my cruise by the Garmin, not the speedometer. There was about a 4 mph difference between the car and the Navus.

[digimuzik]

One thing to note...or not...it's tangentially related...

I'm sort of glad the nav unit gets its speed from the vehicle... since that's what the LockPick takes advantage of. When enabled, my nav unit says I'm going 0mph (and then enables all functions).

Hmm. I haven't yet looked into whether that affects the dead reckoning; but the first time I drove in a parking garage with nav (and no LockPick yet), that feature was insanely cool. Fortunately the LockPick is easily toggled...