Prof430

Hi guys!

My 2002 nav unit keeps on losing my current location. I re-calibrate and everything's ok for a day or 2, then I'm way off, like 20 miles from my current actual location.

Tips and suggestions greatly appreciated.

Thanks

Tom57

Have you ever replaced the Nav disc in the Nav player?

Prof430

Thanks Tom.

Yes, I replaced the disc awhile back with a newer version.

Tony

Tom57

I'd first check and clean the disc (carefully) to be sure there is no haze on it. Re-insert disc - it's possible that the disc was slightly dislodged in the Nav player too. If that's not the problem, since it's an '02, I'd say it's the Nav player - which many of us have had to replace and upgraded to Gen 4 from a later model year (like '06). The lens reader goes bad (weak) after time and cannot read the disc correctly. There are several existing threads on this plug 'n play Nav upgrade. Here is the most recent with posts and links to others.
https://www.clublexus.com/forums/ls4...o-gen-4-a.html

Lavrishevo

iTrader: (1)

I don't think it is a disk error but you could also try resetting the system.

http://www.wikihow.com/Reset-Your-Na...ystem-in-Ls430

I don't know if this is any more effective then just pulling the negative on the battery for 10 seconds. You can actually go back to older generation disk by resetting the system. If you don't reset you cannot go back to an older firmware. I recently got a disk error and the nav unit was acting weird for a few min. I pulled mine apart like the link shows and blew out the interior and also cleaned the disk with a lint free cloth. I have not had issues since. There is a battery on the nav logic board. I wonder if this battery should be replaced after so many years?

Tom57

Lav, You have a 2004 LS which is the more robust factory Gen 4 Nav player. The Gen 2/3 players in '01 - '03 have issues that the Gen 4 haven't as yet presented, besides age / use. The wrong location symptoms Tony is having are the same initial symptoms I had in my '01. Cleaning the Gen 2/3 Nav player lens has been tried by many (including me) and it hasn't been a long-term solution in the Gen 2/3 Nav player.

Lavrishevo

iTrader: (1)

This is kind of interresting. I may pull mine open again and replace the battery.

Lavrishevo

iTrader: (1)

Yeah, I understand what you mean. Sounds like it is common for these units to start failing at his age. I was not thinking the unit was particularly dirty but that a reset might help. The battery thing has me intrigued. I believe it was a 2032 battery. It was about that size. I did not actually remove it off the logic board.

Tom57

I believe that battery is to save memory in the Nav CPU when the main 12-volt battery is disconnected, although as you know, some memory (Destinations) are lost when main battery is disconnected. Maybe those "Destinations" ARE lost because the small wafer battery is dead too?

Tom57

It wouldn't hurt to try a reset, of course. I tried that and more before coming up with the solution to upgrade to Gen 4 Nav player (inexpensively). These Nav reader issues always start intermittently, and when you do something and it works, you think you've solved it, only to find over time that the symptom more often than not, returns.

Lavrishevo

iTrader: (1)

It may remember GPS location data as well when the car is turned off. This does not explain why it does not sync back up properly though. That is probably just like you explained. The unit is probably reaching the end of its life cycle.

Tom57

The GPS location is a constant connection with triangular satellite connection. No memory needed.

It could also be the receiver inside the Nav player is no longer able to perform the triangular location calculation correctly ...

StanVanDam

In the trunk GPS unit, double-check all harness connections. Sounds like the plug for the GPS antenna is loose (if I recall correctly, it's grey and looks like a coax/single-pin) or the speed sensor wire is loose (purple if I recall correctly), or if you installed a switch to cut off the speed sensor to enable typing in motion, make sure you flip it back to complete the circuit when you are done typing.

The speed sensor wire also runs into the nav unit at the front, and the GPS sensor itself it located in the front. You want to double-check those connections also.

The speed sensor is essential for the GPS to maintain accurate position, as the Lexus GPS unit requires a combination of dead reckoning AND a GPS signal to track vehicle position. Which reminds me, try going into the secret nav screen and reset the offsets that the system learned, and do a system trouble code check.

If you live near a military installation (or anyone else "testing" GPS jammers), that could also cause your problem.

toddmorr

curious if anyone has actually replaced this small battery in the nav unit? I pulled out my nav box from the trunk, but there doesn't appear to be any obvious way to open up the box and get inside to replace the battery. I did remove all the screws holding the box together but didn't want to really tear it apart, fearing I might damage something inside.