Make sure that the ignition switch is switched off before going on with the checks. Remove the connection of the high tension lead from the secondary terminal of the coil. Take off the distributor cap, rotor and its cover. Screw remove the black/yellow wire in terminal A (+) and the white/blue wire in the terminal B (-) in the distributor. To measure the primary resistance, connect probes of the ohmmeter across the primary terminals A and B of the coil. Remember always to first disconnect the coil from the circuit. Next, measure the secondary resistance with probes touching the secondary winding terminal and the positive primary terminal A: The mentioned above special resistance values are valid at the coil temperature of about 70 degrees F; in the case when the coil does not coincide with the readings on the specified values, it should be replaced. To remove the coil, the consumer needs to disconnect the cable from the negative terminal of the battery, if the vehicle has a distributor, then one has to remove the distributor cap together with the leak cover, if available, and unscrew the wires connected to the primary terminals. If the coil is to be replaced, then the screws have to be unscrewed and the coil has to be slid out, lifting it from the distributor and installation must reverse the process.