2020 GMC 2500HD Denali Intermittent GPS/Nav Problem

[skatville]

2020 GMC 2500HD Denali

 

This intermittent problem was detected and all attempts to fixed it have failed since the vehicle was new in July 2020.  GMC Service is at Dublin Buick GMC in Dublin, CA

GPS/Navigation failure observations:

1-The GPS fault icon on the screen shows a red circle with a cross line.

 

2-Eventually, the navigation curser moves off of the direct path and erroneously to a location where there are no roads or into buildings.

3-The DIC compass display (N,E W,S, etc) still seems to work correctly and responds in real-time. On occasion, the DIC will show CAL in place of the compass direction.

4-I can’t confirm, but it seems like the outside temperature display does not update when the GPS fails.

5-Every time- NOTE: Every time, I call ONSTAR and the operator answers, the GPS failure icon goes away and the normal navigation icon appears.  GPS/Nav starts working.  This seems to last for a while.  I have traveled for over 900 miles (no towing) with no problems at all.  I got home and starting taking shorter trips to the store and etc. and GPS failures started occurring.  Calling ONSTAR resolved the GPS error immediately.  However, after some intermittent time, GPS error would re-occurred.

 

Problem existed since new- July 2020.  I find it impossible to contact an engineer who understands the system enough to help solve the problem.  Next week I hope the F module gets replaced.  Yes- Sept. 2022.  The shark antenna has been replaced twice and the cable once.  New software (firmware) was the last repair attempt.