Measuring the resistance of the ignition coil (Fiesta 4)

Reliable measurement is possible if the engine control unit is working properly. Ignition systems of 96 series models can be checked with a universal measuring device in resistance test mode.



SEQUENCE OF WORKS

1. Turn off the ignition.

2. Disconnect the high-voltage wire from the ignition unit.

Measuring primary resistance

3. Disconnect the universal electrical connector.



Fig. 9.9. Arrangement of contacts in a universal electrical connector

4. Connect the ohmmeter in series to contacts 1 and 2, 3 and 2 (Fig. 9.9).

5. The resistance should be within 0.4–0.6 Ohms. Otherwise, replace the ignition unit.

Secondary resistance is not measured

In older Fiesta models, you can also measure the resistance of the primary and secondary windings of the ignition coil. If the results are below the required values or the measuring device shows infinity, the ignition coil must be replaced. The measurement must be carried out at room temperature (20°C). Before measuring, turn off the ignition and remove or disconnect all wires from the ignition coil. The resistance is measured between contacts "15" / "+" and "1" / "-" of the "ground", as well as contacts "1" / "-" and "4". An interturn short circuit cannot be diagnosed by measuring. If large discrepancies are found during measurement, replace the ignition coil.