Sat Nav Calibration

[botogol]

I have a problem with the Sat Nav on my three-year old Previa: In short I arrive at every feature BEFORE the the Sat Nav expects me to - that's to say that at at the moment I arive at nearly every roundabout and junction, the Sat Nav is still showing 50-100 yards (or so) to go. (Then when I take the turning, it often becomes lost for a moment or two)

This is something that's developed over time. When the car was new everything worked properly.

I've checked the manual and my guess is that the Sat Nav is having trouble calibrating with the odometer on vehicle- i.e. the car is travelling very slightly faster than the the Sat Nav realises. Therefore I've tried the "tire change" option to get it to recalibrate. Initially, Tthis does indeed seem to help initially but the problem does'nt go away.

It's rendering the Sat Nav very difficult to use - especially in town where 100yds is the difference between this block and the next one.

Any suggestions? Am I on the right track? Is there anything that could cause this problem? anyone else have it?

(Needless to say, my Toyota dealer is absolutely clueless, and the only suggest they can offer is to buy a new CD..or a new Sat Nav system)

[T V O R]

Are you using the TNS200 or TNS300? UK (CD version) or UK and Europe (DVD version)?

[botogol]

the TNS200 UK CD.

[jaxx]

i dont have the toyota system, but the alpine one i do have requires you to select a calibration option if the car when you change the tyres etc or do anything within them sort of lines. it then uses GPS and monitors the speed pulse to calibrate itself.

unsure if the TNS system does this sort of thing???

have you fitted new tyres to your Prevvy that may have a slightly larger profile?? as this will throw distance travelled out quite conciderably?

other than that i suggest trying to get your speed pulse checked to make sure it is still in tune with the wheels rotating

[T V O R]

Umm

Last resort?

Disconnect the power (battery) this will re-set everything, then do the re calibration.

Other than that I’m not sure.

[botogol]

thanks for the advice on this.

the system does indeed monitor the speed of the car, and uses this in conjunction with the GPS (it says so in the manual). I imagine this is a big part of any in car GPS in a town, where reception can be harder.

The system has an option called 'tyre change' which you use to recalibrate after any change like new tyres as I mentioend. But all the equipement on my Previa is standard.

Is it possible that bad wheel alignment could cause this? Not that I think my wheels are misaligned.

Perhaps the speed pulse is so far out, it's beyond the calibration of the GPS. But this seems unlikely to me.

one last question - any ideas on where else I could turn for help - is there any official Toyota helpline I could contact for advice?

[jaxx]

sounds odd. if all equipment is std then you should have no problem. only thing i can think of is (and going by your loaction) that driving round in very built up and city areas with the added 'noise' of radio waves may be causing discrepencys??

try it out in the country lanes and see if you get the same result.

the GPS also normally over rules the speed pulse as its primarily positions you with the GPS and uses the SP for a backup in particular if your in a built up area.

i strongly suggest having such a thing checked by toyota

[botogol]

thanks for the help jaax.

my local toyota dealer is completely clueless, and not actually very interested in solving this.

The latest suggestion is to spend a small fortune upgrading to the DVD version.

perhaps I need to go further afield.