Conditional formatting for specific character count

Hi! Hoping to have some assistance.

I have a spreadsheet of thousands of vehicles and VIN numbers. VINs are exactly 17 characters.

I need to conditional format (highlight) cells in which the character count is BELOW or ABOVE 17 characters. (Meaning the VIN was entered incorrectly.)

I can only find conditional formatting for values greater than/less than/equal to. In this case I’m not worried about the value, just the character count.

Any assistance would be appreciated, thank you!