Hello & Welcome to Just Answer,
Sorry I didn't see your question earlier and to hear of any issue you are having with your device.
To help you with this issue, may I ask:
1) What is the FULL Make & Model Number of the GPS device you are working with?
2) The AGE of the device?
3) WHEN this issue first began?
4) Is the GPS "removable" from any mount, and if so, does the device operate properly OUTSIDE of the vehicle (or in another similar vehicle)?
I see it has been a few days and I just wanted to follow up to see if you have any more questions concerning this issue or if the issue was resolved?
I look forward to any further questions or results that you may have.
Thanks, ***** *****--. .-(im)