don1

Does the ES navigation system also use a gyroscope to sense vehicle motion? The reason I ask is that when driving on city streets where there are frequent turns my nav often loses the street it's on and even the direction the car is going. It seems to me there should be a device such as a gyroscope to sense directional changes and to fill in between lost GPS signals.

Mike728

If your city has tall buildings, you can temporarily lose the GPS signal, which is probably what you're experiencing.

don1

Mike, there are generally few tall buildings where I live. Yesterday I was in a small town with only houses in the area and the nav could not track me while I made several turns. I had guidance on too but it was off by a street. Once I got on a main street it got on track but that took over a minute to happen.

Mike728

Something is not right, then. You should take it in and have it looked at.

Arty101

Agreed. Doesn't sound right so have it checked out.

lamikela1

It's not really a gyro but INS (Inertial Navigation System) It senses movement and determines what direction and speed the car is traveling. I am not sure if the Lexus Nav uses INS but my 9 year old Pioneer Nav on my Tacoma has it and it's pretty darned accurate. If I can find anything on TIS I'll let you know.

lamikela1

Here is what I found... I don't think you'll find any gyros spinning around in the Nav unit but they do call it a "gyro sensor". it's really just an integrated circuit that senses movement.

"The combination of autonomous and GPS navigation makes it possible to display the vehicle position even when the vehicle is in places where GPS signals cannot be received. When only autonomous navigation is used, however, the mapping accuracy may slightly decrease.

(b) Autonomous navigation

This method determines the relative vehicle position based on the driving track determined by the gyro located in the multi-media module receiver assembly and the vehicle speed signal.

(1) Gyro sensor

Used to calculate the direction by detecting angular velocity. It is located in the multi-media module receiver assembly.

(2) Vehicle speed signal

Used to calculate the vehicle driving distance."

don1

Thanks lamikela1. I didn't really expect a physical gyro just a device that acts like one and your info seems to verify this. This description is very much like that supplied with the brochure I have for the 2006 Acura TL which I had purchased in late 2005. I would expect that all late model cars with a nav would use a similar system but could not find any information for the ES. The way mine is acting I'm wondering if the sensor is not functioning. I will have it checked at my next regular service.

lamikela1

You would really need to be in a tunnel or a closed in garage to be able to check it. Even around tall buildings you may still get some sporadic sat signals that would probably take priority over the INS but would not be very accurate if only a couple of sats were available.