bluelexus3

Hello everyone!
I've been a lurking since buying my RX back in March, buy now I need your input. The Nav sometimes loses its positon. So it will display my current location correctly and then all of a sudden it will tell my that I'm on a different street. Sometimes a different city or even county. It has happen to me 5 times already. It occurs randomly but lately it will happen at around 7pm. Took it to the dealer already and they couldn't duplicate the problem and the system wasn't showing any errors. This lost of position would last from 30min till the morning. Any info or input would be greatly appreciated.
Besides that, I love the car.
TIA.

salimshah

Have the dealer run diagnostic test.

Since I am not familiar with the OEM GPS in RX, but the following are the generic things to look at.

Usually the problem is due to lack of signal from the antenna. Is your antenna being blocked by tint.

Is there a history mode? If so, you can store that information and replay it for the dealer and show an instant jump from one place to another.


Salim

bluelexus3

salim
The car has OEM tint in the back and every RX has it. As for the history mode, there isn't one. I took pictures of the errors but the dealer still couldn't duplicate it or figure out the problem.

rxdriver

If the dealer is lost, they need to escalate it. Since you've got proof, the old "can not duplicate" doesn't hold water. If they won't escalate, tell them you'll call Lexus corporate yourself. Replacing the nav parts can be expensive depending on what the problem is, so the dealer may have to get permission from them anyway before proceeding.

I agree that it's probably an antenna problem. FWIW, the antenna is in the top of the dashboard behind the passenger airbag on an RX330; I would imagine it's the same on the RX350.

jerrsRX350

Definitely sounds like an antenna problem. If it only fails periodically it sounds like the antenna wire is disconnecting at the antenna or at the Navigation Unit under the floor boards in the back.

Lil4X

I've had similar problems with a laptop based GPS I used prior to the availability of a Lexus Nav system. Without an inertial dead-reckoning system for backup (such as the RX system has) upon loss of signal, the software logic would stay on track for a few minutes before the cursor wandered off on its own. This would appear to be more than just a simple loss of signal, but you can check your downlinked signal by going to the test mode. "Jumping" to another fix would seem to indicate a computer problem, unless the computer is not receiving time-speed-distance input from other sensors.

Be sure that your car can "see" a large sector of open sky first, and leave the ignition on for this test.

On the 350, I believe you select Menu, Volume, then do the top-left, bottom-left, top-left, bottom-left dance on the corners of the screen to see the "service" menu. I'm not familiar with the system on the 350, but there should be a bar or two that refers to the GPS. Press these (don't change any settings) and somewhere you should see a screen that is showing you the azimuth and elevation of the satellites you are ranging, and a rapidly changing timing display as data is streaming down from the satellite.

At the bottom of the display you should see a "Display Type" or something similar that says "3-D" or "2-D", indicating whether you have a 2 or 3 dimensional fix:

• 2-D You are ranging from 2 birds, giving you two possible locations, only one of which is on the earth's surface, the other somewhere in space. The computer discards the "illogical" fix, assuming that you are on the earth's surface, but that single intersect may not be entirely accurate.
  
  
• 3-D You are ranging from 3 birds, providing a cross check of your fix, and better refining its accuracy (this can also provide you with an altitude calculation as well, that is reasonably accurate). When the three range arcs from each of the three satellites are compared, the resultant "fix" is assumed to be at the center of the small triangle of space between them. If the system is able to lock up three satellites with good signal strength over widely separated segments of the sky, the "averaged" fix should be quite accurate to within 25-30 feet.

If you see these displays but no satellites appear on the list, and no fix is indicated, your problem is either the antenna or the antenna amp, or the connection to the computer that both feeds signals from the antenna and powers the small RF amplifier in the antenna. Your dealer should know how to perform this test.

Anyone out there with a 350 that can be more specific on the diagnositc procedure?

puddintane

my 99 ls exhibits the same behavior, but only when it is cold, and then for about 20 minutes before it rights itself; my 2006 GX is always right on the button. My ls problem is definitely not an antenna; has to be part of the software.

bluelexus3

Lil4X- I got into the service menu but there is no "display type" button.
puddintane-did you ever get the software fix?