When using the diagnostic tool on a Whirlpool dishwasher to find any problems, you'll most likely see the code "D1" flash on the LCD screen. This is not an error at all and just an indication light.
Press the operational buttons to activate the diagnostic setting for the dishwasher. This can be different for various Whirlpool models. After you enter the code, the "D1" will flash on the screen followed by "88."
The "D1" display properly indicates that you have entered the diagnostic mode. If you don't see this flash on the LCD, then you're not in the proper mode.
Instead of looking at the "D1" code or the LCD screen for errors, view the blinking LCD lights for the proper dishwasher error. Follow the diagnostic codes from your manual to assess the fault.