Turn distance is off (by 60 or 70 feet)

Hi Ron. My 1490 is similar to your 1450. I've never encountered the problem you are having. I'm going to guess that you have a defective unit that needs to be exchanged. But that's just my guess.

You didn't mention how long the GPS had been turned on before you noticed this peculiarity, but normally the GPS will acquire adequate accuracy within a couple of minutes, provided it has a reasonable view of the sky.

As far as the specific intersection in question, this error could happen if you were in a city environment surrounded by tall buildings, for example. In such a situation, the GPS may only be able to 'see' two or three satellites directly overhead, more-or-less. Satellites in a tight group provide a very poor 'geometry' to accurately determine position. For best accuracy, the GPS needs satellites widely spaced apart.

I don't know if that was your circumstances or not, but was just trying to read between the lines, so this may not apply at all.

My 1490 is pretty much spot on with the turn distances also.

Have you tried a hard reset? Even a new unit might benefit from one.

Try updating or reverting back your old basemap. It's called gmapbmap.img usually in your .System folder on your garmin device. This helped for me when 2012.10 rolled out (had same problem). But I had no problem with 2012.30 mapset.

My 765t is doing the same thing. It also tells me "Arriving at Destination" almost 70ft before I get there.

I always get an Arriving at destination before I get there. That's normal.

Hi,

Thanks for all the help. The problem as described was not on my old Nuvi 255W. When I was sitting at the crosswalk, the distance would be an accurate 10 feet etc. Now, on this new 1450LMT, if I am sitting at the crosswalk, for a turn, the distance will be anywhere from 60 feet to 100 feet.

I suppose I can live with it but is unnerving.

One suggestion was a hard reset and it seems reasonable, but if I do this, will I have to re-install the level .20 and .30 maps again along with adding the fix for seeing the Junction View?

Thanks,

Ron

No, your current maps will remain intact. You should backup your current.gpx file first though or use MapSource/BaseCamp to back them up. They will be gone.

EDIT: JV will also remain intact.

I also have the 1450 and am having issues with the map being inline with the gps coordinates. after an number of tests it appears to be a mapping problem. Please see my posts and the string of dialogue that followed.

I did a hard reset and it is still off about 60' at a turn. Wonder how many people who own a 1450 are having the same problem. I plan to contact customer support. If you find a fix, please let me know and I will do the same.
Thanks

I've never heard of this 60 foot problem. If you navigate to a POI where you have to take a right turn onto a street where you are 60 feet short of the intersection, what happens if you navigate to the same POI from the opposite direction and have to make a left turn? Are you still 60 feet short or are you 60 feet closer?

I have a 855 and 3790lmt and I notice that as I get closer to the intersection that the distance do get shorter until I am in the middle of the intersection and my distance is as close as 5 feet while I make my turn.

have you tried some simulations and watched the distance viv-a-vis the vehicle location?

HI,

After looking at the thread for VBFRANK I think I have the answer but the software support should look into this.

I noticed that one comment in VBFRANKS thread talked about problems with mapping some streets which are the usual left and right side of the street flipping numbers back and forth VERSUS doing incremental addressing up one side and down the other. It just so happens that the maps on my 255W did not map the inside streets of my manufactured home park. It only had the street address of the entire park. Now, with the 1450, the entire park is mapped including 'street name and number.'

My guess is that the assumptions about alternate side numbering is used and it is incorrect and leads to the overall problem.

What I am going to try is going up (or down) the street one house away (as we are about 75 feet apart) and hopefully, fake out the GPS by about the distance that it is in error. I will call the new setting as 'Home" and see if I fix the the problem.

I have a similar problem with my Nuvi 750.

I get to the turn, but the GPS says I have at least 100 feet to go.

I think it is a problem with the latest maps?
Not sure.

Anyway, It doesn't bother me much.

I did a simulation and the little vehicle is real close to what the measurement indicates. The icon has to travel to the middle of the intersection. The incon was anywhere from 0 to 3 ft in the middle of the intersection.

I hope ronaldb999 and vbfrank will try this alos and report the results.

Unless I'm somehow misreading this thread, the device always gives advanced notice of an upcoming turn, and is speed dependent from what I've seen on both my units. That is, the higher the speed, the more advanced the warning.

A 60-70 foot warning is normal for an upcoming turn at street speeds. At 30 MPH, you're moving at 45 feet per second. Telling you to turn at the last second is stupid, and useless, right?

Again, I may not be getting what the OP said correctly.

OK, here is what I did... I entered an intersection from opposite directions and when the GPS (on the dash) was in the center of the intersection I stopped to get a reading and each time it said I had about 20' more to travel before I was turn. It would zero out just past the intersection. Then when I pulled up my driveway and stopped, the vehicle icon on the GPS showed that I was 60' - 80' further down the block traveling on a street parallel to my driveway.

Ok, 20 feet is a 6 meter accuracy. Not the greatest but in spec depending where you are.

As to the driveway/ parallel street foible, your unit isn't set to 'Off Road' is it? Off road doesn't 'stick' the vehicle icon to a road.

Didn't see that asked.

Not off road. Thanks for trying to help.

Sounds like it's RMA time, or a return for a different unit.

I recently upgraded maps on my 1450LMT and I noticed on my last trip that turn distance off by 80 feet? Is it maps issue or my GPS requires some kid of recalibration?

I assume you were in routing mode and were looking at the turn distances.

When you say that your "turn distance" was off by 80 feet, how were you calculating that? Was the turn early or late?

One possibility might be the accuracy of your satellite coverage.

I don't know of any calibration mechanism for the GPS, the position coordinates being determined by the result of calculations based on the satellites signals it receives. However, these calculations plus the positioning on the current map take more or less time and if you're moving, the position (hence the turn distance) it displays is what it was when it sampled the satellites signals so depending on your speed, your current position might be a bit different.

Different maps, computer/memory load, etc. may result in different calculation times and different "delayed" position.

I have notice the same thing. Unless I know where I am going, I am never sure where the final destination is.

I was a first car at traffic light waiting for green light and GPS was showing that there are still 100 feet before right turn. Once the light changed and I started to turn, GPS was showing 80 feet to go. This issue came up after I upgraded to 2013.40 version using Garmin Express. I noticed this issue on multiple occasions.
Is any one else has this issue?

My Garmin 1450 is always off by 40 to 60 feet. It is especially a problem at night when I am on streets I can't see the names of, I seem to pass the street before I realize I have passed them. I talked to Garmin and they said that was within their limits of tolerance. I got them to send me another anyway and this one is no better. What is wrong with the 1450? My old Nuvi 350 is perfect.