Hello Everyone,
It's me again with the same truck (my dad) with a different problem.
The GPS is off some time like 10-20 miles, sometime half a mile. I read a while back and don't know where that the antenna cable wasn't connect in this case.
I just run the diag for the GPS and here is what it show. I would like to know where is the NAV unit and antenna locate so I double check the connection.

Thank you very much

 

The navigation unit is located under the front passenger seat.
The antenna is under the dash near the center speaker:

https://www.lexussouthatlantaparts.c...rimLevel=19100

You can see if the antenna is receiving by looking for the blue "GPS" box under the compass on the display (where you touch to change from "north is up" to "direction is up". Make sure you're outdoors - the signal will be blocked if you're in a garage or don't have a clear view of the sky.

I doubt this has an effect, but you might want to check anyways ... the compass (in the mirror) has to be set for the part of the US you're in. The direction to the north pole will be different if you're in California than if you are in Virginia. There are instructions in the owner's manual for setting it.

Chip H.