electrical problem

[Creede]

I have a 2009 GMC worktruck. On a recent 300 mile trip the following happened:
The speedometer and tack went to zero then fluctuated engine power came and went, doors locked and unlocked. warning icons appeared. This went on for 15 to 20 seconds. Power returned, tack and speedometer returned to normal and one by one the warning icons went away. About 30 minutes later it happened again. Never happened again on that trip and has not happened again. Not a good felling.
Any help will be appreciated.
Jack

[PhilB]

My first guess would be the ground wires for the electrical system.  Check the ground wire from the battery making sure it is in good shape and has a good connection to the truck.  Also check the positive cable from the battery.  IIRC, there could be corrosion inside the cable that could cause issues.