My (Prius) navigation system is lost

In another thread I mentioned that I had trouble finding my aunt’s house and a large church with the navigation system in my 2005 Prius. The house is on a gravel road off of a small rural road, so I’m not that surprised. But the church should have been easy.

To find an address, you enter the street number first. Then enter the street. Letter disappear from the keypad so that you can only enter valid street names. After the system thinks you’ve entered enough letters it will display street names from which you can choose. In neither case on this trip were the options correct, and there is no way of spelling out the whole street name to override the options. Here’s the thing: When I found the house (using the MapQuest directions I had with me) and marked it on the nav. system the address and street name were displayed. (The number was wrong by one digit.) So obviously the street (or gravel road) was in the system. It seems that in order to find an address you have to input a street number that the system considers valid. Unlike MapQuest it will not get you close (i.e., offer a block range). I also noticed that several gas stations between western Washington and Idaho were not displayed.

I was rear-ended a couple of months ago and an antenna booster that lives behind the rear bumper was crushed. Could something have happened to the nav. system? On the other hand, the first time I tried to find my house it said it didn’t exist. (I marked the location and entered the address manually to tell it where it was.) So that leads me to believe that the system is working as designed.

Why would it not be able to find valid addresses?

Nav systems can be fun. The deal is the they have to be programmed by people driving up and down the roads. A bit labor intensive to say the least.
bottom line is the bigger the town, the better your chance of having the system be right.
When you are in BFE, it can be a crap shoot.
I once programmed one system for the address of a motel in Solvang Ca. When I got to Solvang, it showed my destination, and the main highway though town, and my motel, but it did not show any of the side streets. My motel was 2 blocks off the main drag. So it showed my destination, but could not direct me there.
In theory every time a new map disc comes out, the details get better.


No, if you lost your GPS antenna, the car would have no clue as to your position.

Though I don’t use the GPS much, it seemed to be working fine before the antenna booster was replaced.

Do people actually drive around to program the roads? I assumed the maps were just maps with the coordinates of the roads added to a database.

You don’t get any map info from the antenna, all it receives is a signal which it uses to calculate how far it is from the satellites.

If your system showed the name correctly once you were on the street, it sounds like a programming error which wouldn’t allow you to select if from the list. Or perhaps the address database doesn’t contain everything displayed on the map, although I would expect points on the map to be drawn from the database.

Yes. I didn’t state that clearly. I thought that maybe the collision might have damaged something (though the computer is, I think, in the middle of the car); and oh, by the way, the antenna booster was destroyed. (But I did not notice any problems with the GPS or radio reception.)

Pretty sure the guts of the satnav are mounted between the dash and the bulkhead.

I actually work in the digital road map industry.

The maps are far more than that. First of all, there’s a ton of information needed to give turn-by-turn driving directions that you can’t get from the coordinates alone. Just a couple of examples: House number ranges. No left turn signs. But there’s actually much, much more than that.



I still don’t use the GPS much, but when I do I find that it doesn’t find the address. When I want to use it I’m usually in a hurry, so I’ve been putting the destination mark approximately where I want to go. This morning I had a phone book…

I entered the number and part of the street, and was given a list of possible streets. No joy. I randomly chose different addresses. None of the addresses were found. And why was the wrong address in Virginia? I looked at the little map of the U.S. on the Destination menu. The Southeastern U.S. region was ‘highlighted’. (I put that in quotes because the map is white with blue lines and the ‘highlight’ is light blue.) I changed the region to the PNW, entered the address I wanted, and it popped right up.

The battery had been disconnected at the body shop while the car was being repaired. Apparently my region was not stored in the EPROM and defaulted to the Southeast. Or someone accidentally changed it.

Not to hijack this thread but I was wondering do the GPS applications have access to speed limit data

No worries; my question is answered.

I don’t know if the GPS in my car has speed limits in its database, but I’ve found its time-to-destination estimates are pessimistic. Data: Given the recent price of fuel and the fairly reasonable speed limit in most places here, I tend to drive the at the posted speed or one or two MPH over.

IME, the GPS bases your ETA on the cumulative average speed. So if you have to go 600 miles and you get on the highway at 60 MPH and then reset everything, it’ll tell you 10 hours for the ETA. If you reset and then get stuck in crawling traffic for a couple of hours before you hit the open road, your ETA will be a lot longer but will get shorter as your average speed goes up.

The GPS I had experience with had two separate average speeds…one was moving average and one included time stopped. The ETA was based on the moving average, so if you stopped at a rest area for 20 minutes, it would just add 20 minutes to the ETA, rather than reduce the average speed and have the ETA screwed up until your average speed went back up.

Google and Mapquest seem to take speed limit into consideration for total driving time when you get driving directions. But you could get a pretty accurate ETA if you just computed city streets at 35 MPH and US and Interstate Highways at 65 MPH.

The map data has that information. Whether the GPS systems use it or use other methods to figure the travel time of a possible route is up to the system designers. For example, the data also has other road characteristics, such as whether it’s a highway, arterial, or residential (and those are just a few of the possible classifications).


I doubt it. I think you missed a step or two: The first thing you have to do is identify the state and city. Then you can give it the street address.

The reason I point this out is that I’ve encountered situations similar to yours, and I discovered that the real cause was confusion over which city the destination was located in. Often, the actual city limits are not where people think them to be, and I was looking for the street in City A when actually it was in City B.

A definite yes for my two-year old Garmin. It even knows which parts of the road have different speed limits than other sections. It seems that it calculates the ETA based on the speed limit for every single portion of road, even slower speeds on the cloverleaf when I switch from one highway to another.

It totally ignores any traffic which I happen to be in, which I really can’t blame it for; it is, after all, a mere database computer, with no access to current conditions. But it also totally ignores traffic lights and stop signs, and that’s something that I wish the programmers would compensate for. My GPS currently gives a great ETA, provided that I don’t spend too much time on side streets. While I’m on the highway, the ETA is dead-on, rarely slipping at all provided that I can keep driving at the limit. But as soon as I hit a traffic light or stop sign, it starts slipping little by little. If they would just allow an average of 15 seconds or so (not just for the actual time stopped at the corner, but for the slowing down and speeding up too) for each one, the accuracy would zoom.

Perhaps yours is different; my car is a 2005. Here’s the way it works: Hit the Dest button on the console. This takes you to a menu. Press ‘Address’ on the touch screen. This takes you to a screen with a Number entry box and a Street entry box. You start typing in Number using the keys on the touch screen. Once the number is entered, choose ‘Street’. The virtual keypad changes to a keyboard. As you type in the letters of the street name ‘impossible’ letters vanish. When enough letters have been typed, the screen switches to a list of street names. If the number/street combination exists in more than one city, a list of cities appears after you choose a street name.

You can enter a city name first, but you have to navigate away from the number/street screen. I don’t know if you can enter a number/street if you’ve already chosen a city.

The first first step is choosing a region. Since I bought the car from a friend, the region was already set and I never had to do that step. After I was rear-ended and took the car to the shop where power was disconnected, the region reset to the other side of the country without my seeing or knowing it. Only rarely using GPS navigation and usually not having time to mess with it (e.g., I’m trying to enter something before the light changes and moving the car disables the data entry screen), it wasn’t until yesterday that I finally noticed the region was incorrect. Now that it’s set I don’t have to do it again – unless the battery is disconnected again.

Interesting. I had presumed that when it eliminates the letters for impossible street names, it was looking at all the street names in this city. But by your description, it is looking at all the possible street names in the entire region. I do realize that most street names are very common, but how big are your regions? If it covers several states, or even a single large state, I’d imagine that there are so many variations and names and spellings that this “eliminate the impssible letters” feature does not save too much effort. Oh well…

I’d have to go out and check, but I believe my region is Washington, Oregon and Idaho. The frustrating thing about the disappearing letters is that there really aren’t that many options given once it decides what you’re looking for. Yesterday I was looking for 333 Calluna Ct. After typing in ‘callu’ it offered two options, one of which was Calluna Ave. Since the ‘Calluna’ part was right, I chose it; only to be told that the street number does not exist. (And the city was in Virginia.)

The main issue here is that you’re dealing with an old school GPS with old and limited maps and limited processing power. Even the cheapest retail GPS’ sold currently have the entirety of the US accessible at once without having to sub-divide the mapping of the US into regions.Ca r dealers tend to be conservative re what they put in their vehicles so your hardware and maps might actually be 5+ years out of date.

Your GPS is fine you’re just at the limits of it’s capability re mapping.

But I like having it built in! :wink:

One thing I’ll have to try is to enter a very long trip. The farthest I’ve gone is Coos Bay, OR, and (this was before the power-down) that’s within the region. Off the top of my head I know a German restaurant at 833 Conti St. in New Orleans. I suspect that if I change the region and enter the address, the unit would provide navigation to there from my house even though my house is in a different region.

I think the trick to using a GPS is to ‘use’ it for a while even when you know the way to where you are going just to get familiar with the way it functions and to learn the effects of the different options; there are some quirks and as you’ve found, they can be difficult to manage while stopped at light if you’re not very familiar with your unit.

A couple days ago I was headed for an address on North Wales Road in the Philadelphia suburb of North Wales. GPS said “No such number found.” The address was for a store that had recently moved so I assumed it was a newly constructed area; the unit listed numbers up to 799 and I was looking for 981 so I set it for 799 figuring the store would be a couple of blocks farther … but when I got there, no, dead end, road ended at 799. Stopped and asked for directions and the guy knew the store I was looking for, told me to head south about nine miles. Messed with the GPS a bit more and Aha, I was on North Wales Road but the address I was looking for was on N Wales Road (the north end of Wales Road, not on North Wales Road) … had to scroll down on the GPS to see the second choice.

Yesterday I parked in Hoboken, NJ and took the train into New York City. Got back in the car and punched the button to route to My Home (in PA), started driving and realized the thing was taking me into the Lincoln Tunnel, into NYC … wtf? … did a panic maneuver onto a side street and rechecked that my destination was Home, yep, started driving again and it went round a block or two and headed right back toward the tunnel … stopped at a gas station and looked at the route the GPS was planning … into NYC via Lincoln Tunnel, down the road a ways, and back out of the city via the Holland Tunnel … Aha I says, went to the route options and moved the slider a couple notches away from Fastest Route toward Most Direct and drove on home without paying two tunnel fares … it simply wanted to get me off of city streets and onto 4 lane highways as soon as possible.

Moral of the story: Get familiar with the unit while you don’t actually need it.