Hi guys. Excuse me for butting in. The disc is not the issue. That is just a memory of addresses and points of interest. New ones become available all the time with the latest new roads and other updates. The only thing the GPS radio can learn from the satellites is location. They don't know when roads are closed or they're being repaired, and they don't know how to plan routes or avoid toll roads, etc. All of that is done in the radio with the road maps on the disc. Once the unit knows where you are many of them will work normally with the disc removed; in fact, you have to remove it on some models to play audio cds. They will ask you to insert the navigation disc when you travel beyond a certain distance and it needs new information for the current area.
Low voltage can be caused by things other than low system voltage from a defective generator or battery. It is just as likely to be caused by corroded or loose connector terminals or a corroded splice. That can trick the unit into thinking it's turned off so it will stop updating the current location. The clue there is that random location it jumps to will be a place you were at previously. Also, it will correct your location after you drive up to a few miles.
If it continually resets to an incorrect location try to determine if it's always some random error or if it always goes to the same incorrect direction and distance. For example, if it always says you're three miles southwest of where you really are, look at the antenna and anything that could interfere with its signal. Most antennas live under the top of the dash board with a view through the glass windshield. A cell phone placed near it can interfere with the signals from two of the three satellites.
There can be a problem inside the unit too but typically when it jumps to the wrong location it will be random in direction and distance and usually a lot more error than just a few miles. As with any radio or computer module you can often begin to predict when the problem will occur after hitting a bump in the road, when the sun shines directly on the dash for a few minutes, and things like that. That type of behavior typically points to a problem inside the unit.
I don't know how it would act if the laser assembly is sticking on its slides. When that happens to a cd player the music will suddenly start skipping back about twice per second until the laser pops free and continues to move. The audio system doesn't know it's playing the wrong information. If yours tends to give the same wrong locations when you're in the same areas, you might consider having the guide rails cleaned and lubricated. Unfortunately most tv repair shops have gone out-of-business and those that are left likely won't attempt to repair a radio they can't get service manuals for and they can't run on their test bench. Cleaning those rails is pretty easy on older Chrysler radios built by Mitsubishi. It's rather involved on Chrysler radios built by Alpine. For a Lexus you will most likely be tied to the dealer and their authorized repair centers. They charge a lot but they rarely troubleshoot down to the defective component level like we do with tvs. They just install new assemblies and new circuit boards. You pay a lot more that way but you're pretty guaranteed the problem is solved and an elusive intermittent problem hasn't been overlooked. They get so many units back for repair that you can be sure they've run into the same complaint before that you have and they will know exactly how to solve it. If there are other common problems with your model that haven't shown up yet in yours, those will be addressed too.
Thursday, March 28th, 2013 AT 8:33 PM