GPS Positioning problem
#31
Super Moderator
Once it gets off-kilter though, it gets really inaccurate, really fast. A couple of nights ago, the nav system thought I spent the night parked in the ocean. (And I live in the western part of the county, nowhere close to the beach). The next morning it got a GPS lock within a few minutes, and was spot-on again.
I had planned to take it to the dealer, but I'm discouraged that the handful of people who have brought it in haven't had an accurate diagnosis and lasting repair.
#32
Lexus Champion
The GPS system was primarily designed for military purposes. It is made available for civil applications such as vehicle navigation (but at reduced accuracy). There are times when it is 'turned off' for such civil applications so you would lose satellite communication. This happens here in Europe every so often, particularly at times of heightened security. When it is turned off the car tries to keep its position by its onboard sensors, accelerometers, etc but may drift, until satellite signals are recommenced.
In Europe we will sonn have the alternative Galileo system, which has been designed from the outset as a civil system and will I think have greater accuracy than GPS for users like us.
In Europe we will sonn have the alternative Galileo system, which has been designed from the outset as a civil system and will I think have greater accuracy than GPS for users like us.
#33
Tech Info Resource
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I bought mine in July. I have only noticed this to be an issue when the car gets extremely hot - OAT ~40+C or ~104+F. I suspect there may be a temperature sensitive component in the GPS receiver, and thermal stress is eventually causing a near failure.
Has anyone noted if the car does this primarily after sitting in the sun, or is it while fully cold soaked or both? Since the receiver lives in the dash, it does get sunlight directly on top with a black surface to boot. It wouldn't surprise me at all if its a thermal issue. I'm sure the underdash temp gets pretty high in direct sun.
Has anyone noted if the car does this primarily after sitting in the sun, or is it while fully cold soaked or both? Since the receiver lives in the dash, it does get sunlight directly on top with a black surface to boot. It wouldn't surprise me at all if its a thermal issue. I'm sure the underdash temp gets pretty high in direct sun.
#34
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lobuxracer, the first time it happened to me, I also thought it was heat related. It was an extremely hot day, and the car had been sitting in the sun. The nav had no idea where I was as soon as I turned it on. The other times it has done it, it did not seem heat related. Once, I had been driving on the highway about an hour and suddenly, it just relocated me several miles away, even though I was just proceeding straight on the same highway it had been tracking me on for 50+ miles. Heat wasn't an issue that day.
#35
Tech Info Resource
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Do you have a V1 radar detector? I do. There have been times I have removed it from the windshield and nearly scorched my hand because it was so hot from a combination of operation and sun. The inside of the car was perfectly comfortable, but the detector was blistering hot.
The GPS antenna and receiver live right under the dash where I normally put my detector. So I suspect that part of the dash will get pretty warm even when the inside of the car feels very comfortable. The best way to test this is with thermal paint or thermal strips. I bet that little antenna/amplifier gets really hot under there, and I know certain kinds of components don't like temps over 60C for long periods. I bet when it's 40+C here, that dash temp is around 70C or 75C. Not enough to fail, but enough to be problematic.
The GPS antenna and receiver live right under the dash where I normally put my detector. So I suspect that part of the dash will get pretty warm even when the inside of the car feels very comfortable. The best way to test this is with thermal paint or thermal strips. I bet that little antenna/amplifier gets really hot under there, and I know certain kinds of components don't like temps over 60C for long periods. I bet when it's 40+C here, that dash temp is around 70C or 75C. Not enough to fail, but enough to be problematic.
#36
Super Moderator
I bought mine in July. I have only noticed this to be an issue when the car gets extremely hot - OAT ~40+C or ~104+F. I suspect there may be a temperature sensitive component in the GPS receiver, and thermal stress is eventually causing a near failure.
Has anyone noted if the car does this primarily after sitting in the sun, or is it while fully cold soaked or both? Since the receiver lives in the dash, it does get sunlight directly on top with a black surface to boot. It wouldn't surprise me at all if its a thermal issue. I'm sure the underdash temp gets pretty high in direct sun.
Has anyone noted if the car does this primarily after sitting in the sun, or is it while fully cold soaked or both? Since the receiver lives in the dash, it does get sunlight directly on top with a black surface to boot. It wouldn't surprise me at all if its a thermal issue. I'm sure the underdash temp gets pretty high in direct sun.
The problem did start after we had that week of 107-110 degree heat index days. (Well, since navigation systems don't sweat, I guess heat indices are irrelevant, but actual temperatures were 97-100 that week)
Now it happens even in mild weather, but it seems to have the most trouble locking the signal during the middle part of the day -- and is most likely to work at night or first thing in the morning.
It doesn't seem to be an atmospheric condition issue. It has had problems locking the signal on beautiful clear days, but this morning it stayed locked the whole way in to work in cool, clammy, rainy weather with dark grey skies.
I've been keeping track of what it sees by using the Menu, volume, top-bottom-top-bottom, GPS information, and when it is misbehaving the only satellites is sees are numbers 2 and 28.
#38
No nav mods here and I've continually had this problem. I've seen others with the problem who are getting the upgraded dvd nav disc to help remedy. May be worth asking your dealer for it. It's what I plan to do.
#39
Super Moderator
Not the problem. First, the region is set correctly. Second, as soon as the GPS gets a valid signal (e.g., the word "GPS" appears under the map scale indicator in the upper left part of the screen), the map positioning corrects itself, to within a few hundred feet within a few seconds, and spot-on within 30 seconds.
#40
Super Moderator
It won't fix the problem, which is a problem with the GPS getting a lock on enough satellites (I believe that it needs to see at least four) to get a lock and calculate your position.
Last edited by Bichon; 09-15-06 at 03:31 PM.
#41
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Join Date: Jul 2006
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I called my dealer today 2x to check on the progress and they haven't even returned my phone call. the service is absolutely awful at my dealer.
ok since this is the 3rd time my car is in the shop for this. if it doesnt work again after i pick it up and they fail to resolve it on the 4th try...i'm asking for a full refund based on the NY lemon laws.
ok since this is the 3rd time my car is in the shop for this. if it doesnt work again after i pick it up and they fail to resolve it on the 4th try...i'm asking for a full refund based on the NY lemon laws.
#42
Tech Info Resource
iTrader: (2)
You may be on to something here.
The problem did start after we had that week of 107-110 degree heat index days. (Well, since navigation systems don't sweat, I guess heat indices are irrelevant, but actual temperatures were 97-100 that week)
Now it happens even in mild weather, but it seems to have the most trouble locking the signal during the middle part of the day -- and is most likely to work at night or first thing in the morning.
It doesn't seem to be an atmospheric condition issue. It has had problems locking the signal on beautiful clear days, but this morning it stayed locked the whole way in to work in cool, clammy, rainy weather with dark grey skies.
I've been keeping track of what it sees by using the Menu, volume, top-bottom-top-bottom, GPS information, and when it is misbehaving the only satellites is sees are numbers 2 and 28.
The problem did start after we had that week of 107-110 degree heat index days. (Well, since navigation systems don't sweat, I guess heat indices are irrelevant, but actual temperatures were 97-100 that week)
Now it happens even in mild weather, but it seems to have the most trouble locking the signal during the middle part of the day -- and is most likely to work at night or first thing in the morning.
It doesn't seem to be an atmospheric condition issue. It has had problems locking the signal on beautiful clear days, but this morning it stayed locked the whole way in to work in cool, clammy, rainy weather with dark grey skies.
I've been keeping track of what it sees by using the Menu, volume, top-bottom-top-bottom, GPS information, and when it is misbehaving the only satellites is sees are numbers 2 and 28.
Another thought - it could also be heat-related frequency drift. The receiver has a local oscillator generating a frequency (assuming it's some kind of super-het receiver), and if the oscillator gets too hot, it could drift and fail to lock on the right frequency to receive satellite data. I'm sure there's an allowable error range, but if the under dash heat is enough to cause the oscillator to drift, it might be enough to interrupt weaker signals.
#43
Lexus Champion
I called my dealer today 2x to check on the progress and they haven't even returned my phone call. the service is absolutely awful at my dealer.
ok since this is the 3rd time my car is in the shop for this. if it doesnt work again after i pick it up and they fail to resolve it on the 4th try...i'm asking for a full refund based on the NY lemon laws.
ok since this is the 3rd time my car is in the shop for this. if it doesnt work again after i pick it up and they fail to resolve it on the 4th try...i'm asking for a full refund based on the NY lemon laws.
"A MANUFACTURER MAY REFUSE TO EXCHANGE A COMPARABLE CAR OR REFUND YOUR PURCHASE PRICE IF THE PROBLEM DOES NOT SUBSTANTlALLY IMPAIR THE VALUE OF YOUR CAR."
#44
Anything less than 3, and your SOL and the system just works on speed sensor input and perhaps a steering sensor / gyroscope. It's pretty accurate in tunnels, but if you do any significant turns without a satellite signal, it'll lose you quickly.
#45
And to comment about the search location. That can be set to anywhere, because that's only used to searching for a destination, and not for where you are currently. Plan a cross-country trip, and you might be in US 9 and are going to US 2. You'll be in US 2 throughout the trip on the location search, but you obviously aren't in that area.