While driving speed does not matter, the dash starts to blink. Speedometer and RPM goes to zero. If I accelerate everything goes back to normal. the car does not stall. No trouble code stored. The cars display shows CHARGING System Failure. Verified battery and alternator, seemed OK. Replaced alternator anyway. Problem still shows up. Also, removed paint from chassis where ground connection is made from battery. Seemed to help for 2 days then problem came back.
Ask shop to keep your car for test drives. When this problem occurs on one of their test drives, they’ll be prepared to measure the battery & charging system parameters.
How old is your battery? If more than 4 years, probably makes sense to try installing a new battery first. Might just solve the problem. Plus you’ll have a new battery, which you will need soon anyway. A good alternator isn’t always able to compensate for a battery on the fritz.