The ornamental design for a cardiagnostictool, as shown and described.
FIG. 1 is a first perspective view of a car diagnostic tool, showing the claimed new design;
FIG. 2 is a second perspective view thereof;
FIG. 3 is a front elevation view thereof;
FIG. 4 is a rear elevation view thereof;
FIG. 5 is a left side elevation view thereof;
FIG. 6 is a right side elevation view thereof;
FIG. 7 is a top plan view thereof; and,
FIG. 8 is a bottom plan view thereof.
The broken lines in the drawings represent boundaries of the claimed design. The broken lines are environmental structures that form no part of the claimed design.