JohnnyCake

Got a call from a friend who upgraded to 8.1 and now wants to revert to 5.1 so that he will get the override back. Can that be done? I told him you guys would know.

Here's what he wrote me:

QUOTE: "I called the local lexus dealer and they told me, once it was updated to the 8.1 dvd, It clears the memory in the hard drive of the older version of software. and the only way to reverse it is to replace the navigation hard drive and re-install the old nav dvd. and I don't want to buy a new hard drive, So I'm stuck with the 8.1 version and I lost the ability to over ride the destination while in motion."

Bon

Put the old DVD back into the NAV unit and then locate the correct fuse for the NAV unit and remove it for 2 minutes or more. This will force a complete reload when you power the NAV unit back up and you'll have your override back. You might want to verify that the you have the right fuse for the NAV system by trying to eject the DVD or the like while the fuse is pulled.

tfischer

What year SC is this? I don't think the SC ever went to a hard drive based NAV system. (If he had a ver 5 disc in his car, it must be at least 3 or 4 years old, and surely does not have a hard drive NAV system.) My '02 SC and '04 RX both read the disc directly, and I swap different versions back and forth between these cars all the time.
The only caution I am aware of is that any version newer than 1 includes an update to the OS itself, and once that is done, the system will no longer be able to read the old ver 1 disc.
Other that that, going back and forth should be no problem, as far as I know.
If this car does have a hard disc based NAV system, however, all this might be different.

JohnnyCake

Yes, I'm talking about getting the old OS back so that the override is functional.

Removing the fuse (or disconnecting the battery, I guess) would clear the memory so it seems logical, but since this isn't for me, confirmation would be good before I pass it along.

Can anyone +1 for Bon's solution?

Harold57

I've never done it myself, but that is the process mentioned in several thread posts in the past.
tfischer, when you revert to an older version, are you having to pull the fuse to make that happen also? What versions are you swapping between?

tfischer

Switching between versions in my cars requires nothing but swapping the discs. Pulling a fuse would be a big pain. It's just like taking a movie DVD out of your DVD player and putting in another. I think at this time I am using versions 8 and 5. I usually put the newer on in a car that I am taking on a trip out of town.

Harold57

BTW, IIRC, the override command lies in a file on the disc. There were earlier threads describing taking the file with override capability from the 5.1 disc and combining it with the latest disc (on a new DVD) to make an overrideable latest version. So that may be another avenue. (I believe that if you own both discs, making a "backup" copy is perfectly legal, so long as you don't sell it or give it away and don't use it for additional vehicles. Then again, I'm no lawyer.)

JohnnyCake

Has the SC ever had a hard drive?

Yes

it must have a small hard drive for the OS. but it doesn't load data (maps) onto it the way garmin does.

JohnnyCake

That's possible but it could also be that it loads the OS into volitile RAM and not have a hard drive at all.

tfischer

There is no hard drive in most Nav systems. Settings and the OS are flashed into chips. This is why, although there is no hard drive in your DVD player, it remembers where you stopped the movie, even if you turn it off and unplug it (at least many good ones do). Same thing for your iPod nano: no hard drive but it remembers everything, even if the battery is drained to zero.
As far as I know, the SC has never had a hard drive based NAV system, but I am not sure. Such systems are just now being introduced on new models, such as the 2010 RX, etc.
This allows for swapping disc between versions, even going backward, with the only limitation, as far as I know, of not being able to return to Ver 1 after using anything newer.