The direction of my car on the map slowly changes - that is, instead of always showing the car heading down the road, it slowly rotates until it looks like it is moving sideways and eventually pointed backwards.

When the car is shown moving in the proper direction, the navigation system calculates routes properly - but when the car is shown moving sideways, etc., the navigation directions are crazy.

I know how to adjust the car direction with the Settings - Change Current Position screen - but the direction always starts to drift off line after a mile or two,

Any suggestions?

check for a bad GPS antenna. We have encountered this at our shop before and what is happening is your gps system is running solely off of the speed sense wire and the gyro. the more you drive, the more off it gets from your actual location because there is no gps signal to re-center the system. go to your hardware screen and check to see if it is recieving any sattelites.

good luck & post your findings.

my nav was off 4 a 1 day, the gps wasn't right n it was running off the speed sense. i unplugged the wire harness, unplugged the gps antenna, unplugged the speed sense. waited bout a minute, plugged everythin back up, then in bout 30 seconds it figured out where it was n it was back 2 normal.

SAME HERE. RESET. UNPLUGED EVERYTHING. PUT IT ALL BACK TOGETHER AND IT WAS WORKING AGAIN. DON'T KNOW WHAT HAPPENED. THE SAT'S ON MY HARDWARE SHOWED 5 ENOUGH TO PICK UP ON MY GPS. ANYWAY GOODLUCK.