Disconnect the battery's negative terminal, ensuring you have the stereo's anti-theft code if needed. Lift and secure the vehicle. Remove the coil's heat shield and mounting bolts. Use an ohmmeter to measure resistance between coil terminals and compare with primary and secondary resistance. If values are off, replace the coil. To do so, disconnect the battery again, remove the heat shield, disconnect wires from coil terminals, remove coil from distributor housing. Reverse these steps for installation.